Merge branch 'ci/fix-release-step-script' into 'main'

ci: fix release step script

See merge request hectorjsmith/fail2ban-prometheus-exporter!101

.gitignore

@@ -4,3 +4,5 @@ vendor/
 
 build/
 dist/
+
+fail2ban_exporter

.gitlab-ci.yml

@@ -1,22 +1,78 @@
-image: golang:latest
-
-before_script:
-  - make install-deps
-
 stages:
   - test
+  - build
+  - release
+
+.go_template:
+  image: golang:latest
+
+sast:
+  stage: test
+
+include:
+- template: Security/SAST.gitlab-ci.yml
+- template: Security/Dependency-Scanning.gitlab-ci.yml
 
 format:
+  extends: .go_template
   stage: test
   script:
-    - make format
+    - make check/fmt
 
-dependencies:
+vet:
+  extends: .go_template
   stage: test
+  allow_failure: true
   script:
-    - make go-mod-tidy
+    - make vet
 
 test:
+  extends: .go_template
   stage: test
   script:
     - make test
+
+build:
+  extends: .go_template
+  stage: build
+  script:
+    - make build
+  artifacts:
+    paths:
+      - fail2ban_exporter
+    expire_in: 1 day
+
+release:
+  stage: release
+  image: docker:stable
+  services:
+    - docker:dind
+  variables:
+    DOCKER_REGISTRY: $CI_REGISTRY
+    DOCKER_USERNAME: $CI_REGISTRY_USER
+    DOCKER_PASSWORD: $CI_REGISTRY_PASSWORD
+    GIT_DEPTH: 0
+  rules:
+    - if: $CI_COMMIT_TAG =~ /^v.*$/
+  script: |
+    docker run --rm --privileged \
+      -v $PWD:/go/src/gitlab.com/hectorjsmith/fail2ban-prometheus-exporter \
+      -w /go/src/gitlab.com/hectorjsmith/fail2ban-prometheus-exporter \
+      -v /var/run/docker.sock:/var/run/docker.sock \
+      -e DOCKER_USERNAME -e DOCKER_PASSWORD -e DOCKER_REGISTRY  \
+      -e GITLAB_TOKEN \
+      goreleaser/goreleaser release --clean
+
+tag images:
+  stage: release
+  image: docker:stable
+  services:
+    - docker:dind
+  needs:
+    - release
+  rules:
+    - if: $CI_COMMIT_TAG =~ /^v\d+\.\d+\.\d+$/
+  variables:
+    IMAGE_NAME: registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter
+  script:
+    - ./.gitlab-ci/tagLatestImage.sh

.gitlab-ci/tagLatestImage.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+VERSION=`echo $CI_COMMIT_TAG | cut -c 2-`
+MAJOR=`echo $VERSION | cut -d "." -f 1`
+MINOR=`echo $VERSION | cut -d "." -f 2`
+
+echo "version: $VERSION (major: $MAJOR; minor: $MINOR)"
+
+docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+docker pull $IMAGE_NAME:$VERSION
+docker tag $IMAGE_NAME:$VERSION $IMAGE_NAME:latest
+docker tag $IMAGE_NAME:$VERSION $IMAGE_NAME:$MAJOR
+docker tag $IMAGE_NAME:$VERSION $IMAGE_NAME:$MAJOR.$MINOR
+docker push $IMAGE_NAME

.goreleaser.yml

@@ -0,0 +1,45 @@
+project_name: fail2ban_exporter
+builds:
+  - env: [CGO_ENABLED=0]
+    binary: fail2ban_exporter
+    goos:
+      - linux
+      - darwin
+    goarch:
+      - amd64
+      - "386"
+      - arm
+      - arm64
+    goarm:
+      - "6"
+      - "7"
+
+dockers:
+- image_templates: ["registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter:{{ .Version }}"]
+  dockerfile: Dockerfile
+  build_flag_templates:
+  - --label=org.opencontainers.image.title={{ .ProjectName }}
+  - --label=org.opencontainers.image.description={{ .ProjectName }}
+  - --label=org.opencontainers.image.url=https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter
+  - --label=org.opencontainers.image.source=https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter
+  - --label=org.opencontainers.image.version={{ .Version }}
+  - --label=org.opencontainers.image.created={{ time "2006-01-02T15:04:05Z07:00" }}
+  - --label=org.opencontainers.image.revision={{ .FullCommit }}
+  - --label=org.opencontainers.image.licenses=MIT
+
+changelog:
+  groups:
+    - title: "⛔ Breaking Changes"
+      regexp: '^.*?!:.+$'
+      order: 0
+    - title: "🎉 Features"
+      regexp: '^.*?feat(\(\w+\))??:.+$'
+      order: 1
+    - title: "🐛 Fixes"
+      regexp: '^.*?fix(\(\w+\))??:.+$'
+      order: 2
+    - title: "📑 Other"
+      order: 999
+  filters:
+    exclude:
+      - "^Merge"

Dockerfile

@@ -0,0 +1,10 @@
+FROM debian:buster-slim
+
+# Create main app folder to run from
+WORKDIR /app
+
+# Copy compiled binary to release image
+# (must build the binary before running docker build)
+COPY fail2ban_exporter /app/fail2ban_exporter
+
+ENTRYPOINT ["/app/fail2ban_exporter"]

Makefile

@@ -1,15 +1,55 @@
-install-deps:
+# List make commands
+.PHONY: ls
+ls:
+	cat Makefile | grep "^[a-zA-Z#].*" | cut -d ":" -f 1 | sed s';#;\n#;'g
+
+# Download dependencies
+.PHONY: download
+download:
 	go mod download
 
-# Standard go test
+# Update project dependencies
-test:
+.PHONY: update
+update:
+	go get -u
+	go mod download
+	go mod tidy
+
+# Run project tests
+.PHONY: test
+test: download
 	go test ./... -v -race
 
-# Make sure no unnecessary dependencies are present
+# Look for "suspicious constructs" in source code
-go-mod-tidy:
+.PHONY: vet
-	go mod tidy -v
+vet: download
-	git diff-index --quiet HEAD
+	go vet ./...
 
-format:
+# Format code
-	go fmt $(go list ./... | grep -v /vendor/)
+.PHONY: fmt
-	go vet $(go list ./... | grep -v /vendor/)
+fmt: download
+	go mod tidy
+	go fmt ./...
+
+# Check for unformatted go code
+.PHONY: check/fmt
+check/fmt: download
+	test -z $(shell gofmt -l .)
+
+# Build project
+.PHONY: build
+build:
+	CGO_ENABLED=0 go build \
+	-ldflags "\
+	-X main.version=${shell git describe --tags} \
+	-X main.commit=${shell git rev-parse HEAD} \
+	-X main.date=${shell date --iso-8601=seconds} \
+	-X main.builtBy=manual \
+	" \
+	-o fail2ban_exporter \
+	exporter.go
+
+# Build project docker container
+.PHONY: build/docker
+build/docker: build
+	docker build -t fail2ban-prometheus-exporter .

README.md

@@ -1,3 +1,205 @@
 # Fail2Ban Prometheus Exporter
 
-Go tool to collect and export metrics on Fail2Ban
+[![Pipeline](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/badges/main/pipeline.svg)](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter)
+
+Collect metrics from a running fail2ban instance.
+
+## Table of Contents
+1. Quick Start
+2. Metrics
+3. Configuration
+4. Building from source
+5. Textfile metrics
+
+## 1. Quick Start
+
+The exporter can be run as a standalone binary or a docker container.
+
+### 1.1. Standalone
+
+The following command will start collecting metrics from the `/var/run/fail2ban/fail2ban.sock` file and expose them on port `9191`.
+
+```
+$ fail2ban_exporter --collector.f2b.socket=/var/run/fail2ban/fail2ban.sock --web.listen-address=":9191"
+
+2022/02/20 09:54:06 fail2ban exporter version 0.8.1
+2022/02/20 09:54:06 starting server at :9191
+2022/02/20 09:54:06 reading metrics from fail2ban socket: /var/run/fail2ban/fail2ban.sock
+2022/02/20 09:54:06 metrics available at '/metrics'
+2022/02/20 09:54:06 ready
+```
+
+Binary files for each release can be found on the [releases](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/-/releases) page.
+
+There is also an [example systemd service file](/_examples/systemd/fail2ban_exporter.service) included in the repository.
+This is a starting point to run the exporter as a service.
+
+### 1.2. Docker
+
+**Docker run**
+```
+docker run -d \
+    --name "fail2ban-exporter" \
+    -v /var/run/fail2ban:/var/run/fail2ban:ro \
+    -p "9191:9191" \
+    registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter:latest
+```
+
+**Docker compose**
+
+```
+version: "2"
+services:
+  exporter:
+    image: registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter:latest
+    volumes:
+    - /var/run/fail2ban/:/var/run/fail2ban:ro
+    ports:
+    - "9191:9191"
+```
+
+Use the `:latest` tag to get the latest stable release.
+See the [registry page](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/container_registry) for all available tags.
+
+**NOTE:** While it is possible to mount the `fail2ban.sock` file directly, it is recommended to mount the parent folder instead.
+The `.sock` file is deleted by fail2ban on shutdown and re-created on startup and this causes problems for the docker mount.
+See [this reply](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/-/issues/11#note_665003499) for more details.
+
+## 2. Metrics
+
+The exporter exposes the following metrics:
+
+*All metric names are prefixed with `f2b_`*
+
+| Metric                       | Description                                                                        | Example                                             |
+|------------------------------|------------------------------------------------------------------------------------|-----------------------------------------------------|
+| `up`                         | Returns 1 if the exporter is up and running                                        | `f2b_up 1`                                          |
+| `errors`                     | Count the number of errors since startup by type                                   |                                                     |
+| `errors{type="socket_conn"}` | Errors connecting to the fail2ban socket (e.g. connection refused)                 | `f2b_errors{type="socket_conn"} 0`                  |
+| `errors{type="socket_req"}`  | Errors sending requests to the fail2ban server (e.g. invalid responses)            | `f2b_errors{type="socket_req"} 0`                   |
+| `jail_count`                 | Number of jails configured in fail2ban                                             | `f2b_jail_count 2`                                  |
+| `jail_banned_current`        | Number of IPs currently banned per jail                                            | `f2b_jail_banned_current{jail="sshd"} 15`           |
+| `jail_banned_total`          | Total number of banned IPs since fail2ban startup per jail (includes expired bans) | `f2b_jail_banned_total{jail="sshd"} 31`             |
+| `jail_failed_current`        | Number of current failures per jail                                                | `f2b_jail_failed_current{jail="sshd"} 6`            |
+| `jail_failed_total`          | Total number of failures since fail2ban startup per jail                           | `f2b_jail_failed_total{jail="sshd"} 125`            |
+| `jail_config_ban_time`       | How long an IP is banned for in this jail (in seconds)                             | `f2b_config_jail_ban_time{jail="sshd"} 600`         |
+| `jail_config_find_time`      | How far back the filter will look for failures in this jail (in seconds)           | `f2b_config_jail_find_time{jail="sshd"} 600`        |
+| `jail_config_max_retry`      | The max number of failures allowed before banning an IP in this jail               | `f2b_config_jail_max_retries{jail="sshd"} 5`        |
+| `version`                    | Version string of the exporter and fail2ban                                        | `f2b_version{exporter="0.5.0",fail2ban="0.11.1"} 1` |
+
+The metrics above correspond to the matching fields in the `fail2ban-client status <jail>` command:
+```
+Status for the jail: sshd
+|- Filter
+|  |- Currently failed: 6
+|  |- Total failed:     125
+|  `- File list:        /var/log/auth.log
+`- Actions
+   |- Currently banned: 15
+   |- Total banned:     31
+   `- Banned IP list:   ...
+```
+
+### 2.1. Grafana
+
+The metrics exported by this tool are compatible with Prometheus and Grafana.
+A sample grafana dashboard can be found in the [grafana.json](/_examples/grafana/dashboard.json) file.
+Just import the contents of this file into a new Grafana dashboard to get started.
+
+The dashboard supports displaying data from multiple exporters. Use the `instance` dashboard variable to select which ones to display.
+
+*(Sample dashboard is compatible with Grafana `9.1.8` and above)*
+
+## 3. Configuration
+
+The exporter is configured with CLI flags and environment variables.
+There are no configuration files.
+
+**CLI flags**
+```
+🚀 Collect prometheus metrics from a running Fail2Ban instance
+
+Flags:
+  -h, --help                          Show context-sensitive help.
+  -v, --version                       Show version info and exit
+      --dry-run                       Attempt to connect to the fail2ban socket then exit
+                                      before starting the server
+      --web.listen-address=":9191"    Address to use for the metrics server
+                                      ($F2B_WEB_LISTEN_ADDRESS)
+      --collector.f2b.socket="/var/run/fail2ban/fail2ban.sock"
+                                      Path to the fail2ban server socket
+                                      ($F2B_COLLECTOR_SOCKET)
+      --collector.f2b.exit-on-socket-connection-error
+                                      When set to true the exporter will immediately
+                                      exit on a fail2ban socket connection error
+                                      ($F2B_EXIT_ON_SOCKET_CONN_ERROR)
+      --collector.textfile.directory=STRING
+                                      Directory to read text files with metrics from
+                                      ($F2B_COLLECTOR_TEXT_PATH)
+      --web.basic-auth.username=STRING
+                                      Username to use to protect endpoints with basic auth
+                                      ($F2B_WEB_BASICAUTH_USER)
+      --web.basic-auth.password=STRING
+                                      Password to use to protect endpoints with basic auth
+                                      ($F2B_WEB_BASICAUTH_PASS)
+```
+
+**Environment variables**
+
+Each environment variable corresponds to a CLI flag.
+If both are specified, the CLI flag takes precedence.
+
+| Environment variable            | Corresponding CLI flag                            |
+|---------------------------------|---------------------------------------------------|
+| `F2B_COLLECTOR_SOCKET`          | `--collector.f2b.socket`                          |
+| `F2B_COLLECTOR_TEXT_PATH`       | `--collector.textfile.directory`                  |
+| `F2B_WEB_LISTEN_ADDRESS`        | `--web.listen-address`                            |
+| `F2B_WEB_BASICAUTH_USER`        | `--web.basic-auth.username`                       |
+| `F2B_WEB_BASICAUTH_PASS`        | `--web.basic-auth.password`                       |
+| `F2B_EXIT_ON_SOCKET_CONN_ERROR` | `--collector.f2b.exit-on-socket-connection-error` |
+
+## 4. Building from source
+
+Building from source has the following dependencies:
+- Go v1.20
+- Make
+
+From there, simply run `make build`
+
+This will download the necessary dependencies and build a `fail2ban_exporter` binary in the root of the project.
+
+## 5. Textfile metrics
+
+For more flexibility the exporter also allows exporting metrics collected from a text file.
+
+To enable textfile metrics provide the directory to read files from with the `--collector.textfile.directory` flag.
+
+Metrics collected from these files will be exposed directly alongside the other metrics without any additional processing.
+This means that it is the responsibility of the file creator to ensure the format is correct.
+
+By exporting textfile metrics an extra metric is also exported with an error count for each file:
+
+```
+# HELP textfile_error Checks for errors while reading text files
+# TYPE textfile_error gauge
+textfile_error{path="file.prom"} 0
+```
+
+**NOTE:** Any file not ending with `.prom` will be ignored.
+
+**Running in Docker**
+
+To collect textfile metrics inside a docker container, a couple of things need to be done:
+1. Mount the folder with the metrics files
+2. Set the `F2B_COLLECTOR_TEXT_PATH` environment variable
+
+*For example:*
+```
+docker run -d \
+    --name "fail2ban-exporter" \
+    -v /var/run/fail2ban:/var/run/fail2ban:ro \
+    -v /path/to/metrics:/app/metrics/:ro \
+    -e F2B_COLLECTOR_TEXT_PATH=/app/metrics \
+    -p "9191:9191" \
+    registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter:latest
+```

_examples/grafana/dashboard.json

@@ -0,0 +1,877 @@
+{
+  "__inputs": [
+    {
+      "name": "DS_PROMETHEUS",
+      "label": "Prometheus",
+      "description": "",
+      "type": "datasource",
+      "pluginId": "prometheus",
+      "pluginName": "Prometheus"
+    }
+  ],
+  "__elements": {},
+  "__requires": [
+    {
+      "type": "grafana",
+      "id": "grafana",
+      "name": "Grafana",
+      "version": "9.1.8"
+    },
+    {
+      "type": "datasource",
+      "id": "prometheus",
+      "name": "Prometheus",
+      "version": "1.0.0"
+    },
+    {
+      "type": "panel",
+      "id": "table",
+      "name": "Table",
+      "version": ""
+    },
+    {
+      "type": "panel",
+      "id": "timeseries",
+      "name": "Time series",
+      "version": ""
+    }
+  ],
+  "annotations": {
+    "list": [
+      {
+        "builtIn": 1,
+        "datasource": {
+          "type": "datasource",
+          "uid": "grafana"
+        },
+        "enable": true,
+        "hide": true,
+        "iconColor": "rgba(0, 211, 255, 1)",
+        "name": "Annotations & Alerts",
+        "target": {
+          "limit": 100,
+          "matchAny": false,
+          "tags": [],
+          "type": "dashboard"
+        },
+        "type": "dashboard"
+      }
+    ]
+  },
+  "editable": true,
+  "fiscalYearStartMonth": 0,
+  "graphTooltip": 2,
+  "id": null,
+  "links": [],
+  "liveNow": false,
+  "panels": [
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "",
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "custom": {
+            "align": "auto",
+            "displayMode": "auto",
+            "inspect": false
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          }
+        },
+        "overrides": [
+          {
+            "matcher": {
+              "id": "byRegexp",
+              "options": ".*Time"
+            },
+            "properties": [
+              {
+                "id": "unit",
+                "value": "s"
+              }
+            ]
+          }
+        ]
+      },
+      "gridPos": {
+        "h": 6,
+        "w": 24,
+        "x": 0,
+        "y": 0
+      },
+      "id": 206,
+      "options": {
+        "footer": {
+          "fields": "",
+          "reducer": [
+            "sum"
+          ],
+          "show": false
+        },
+        "showHeader": true
+      },
+      "pluginVersion": "9.1.8",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": false,
+          "expr": "f2b_config_jail_max_retries{instance=~\"$instance\"}",
+          "format": "table",
+          "instant": true,
+          "interval": "",
+          "legendFormat": "{{jail}}",
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": false,
+          "expr": "f2b_config_jail_ban_time{instance=~\"$instance\"}",
+          "format": "table",
+          "hide": false,
+          "instant": true,
+          "interval": "",
+          "legendFormat": "{{jail}}",
+          "refId": "B"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": false,
+          "expr": "f2b_config_jail_find_time{instance=~\"$instance\"}",
+          "format": "table",
+          "hide": false,
+          "instant": true,
+          "interval": "",
+          "legendFormat": "{{jail}}",
+          "refId": "C"
+        }
+      ],
+      "title": "F2B Config",
+      "transformations": [
+        {
+          "id": "merge",
+          "options": {}
+        },
+        {
+          "id": "groupBy",
+          "options": {
+            "fields": {
+              "Value #A": {
+                "aggregations": [
+                  "lastNotNull"
+                ],
+                "operation": "aggregate"
+              },
+              "Value #B": {
+                "aggregations": [
+                  "lastNotNull"
+                ],
+                "operation": "aggregate"
+              },
+              "Value #C": {
+                "aggregations": [
+                  "lastNotNull"
+                ],
+                "operation": "aggregate"
+              },
+              "instance": {
+                "aggregations": [],
+                "operation": "groupby"
+              },
+              "jail": {
+                "aggregations": [],
+                "operation": "groupby"
+              }
+            }
+          }
+        },
+        {
+          "id": "organize",
+          "options": {
+            "excludeByName": {},
+            "indexByName": {},
+            "renameByName": {
+              "Value #A (lastNotNull)": "Max Retries",
+              "Value #B (lastNotNull)": "Ban Time",
+              "Value #C (lastNotNull)": "Find Time",
+              "jail": "Jail"
+            }
+          }
+        }
+      ],
+      "transparent": true,
+      "type": "table"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "",
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": true,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "min": 0,
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 6
+      },
+      "id": 190,
+      "options": {
+        "legend": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "displayMode": "table",
+          "placement": "right",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "pluginVersion": "8.2.1",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": true,
+          "expr": "f2b_jail_failed_total{instance=~\"$instance\"}",
+          "hide": false,
+          "interval": "",
+          "legendFormat": "{{jail}} ({{instance}})",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Fail2Ban Failures (Total)",
+      "transparent": true,
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "",
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": true,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "min": 0,
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 6
+      },
+      "id": 191,
+      "options": {
+        "legend": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "displayMode": "table",
+          "placement": "right",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "pluginVersion": "8.2.1",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": true,
+          "expr": "f2b_jail_banned_total{instance=~\"$instance\"}",
+          "interval": "",
+          "legendFormat": "{{jail}} ({{instance}})",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Fail2Ban Bans (Total)",
+      "transparent": true,
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "",
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": true,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "min": 0,
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 14
+      },
+      "id": 208,
+      "options": {
+        "legend": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "displayMode": "table",
+          "placement": "right",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "pluginVersion": "8.2.1",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": true,
+          "expr": "f2b_jail_failed_current{instance=~\"$instance\"}",
+          "interval": "",
+          "legendFormat": "{{jail}} ({{instance}})",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Fail2Ban Failures (Current)",
+      "transparent": true,
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "",
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": true,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "min": 0,
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 14
+      },
+      "id": 209,
+      "options": {
+        "legend": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "displayMode": "table",
+          "placement": "right",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "pluginVersion": "8.2.1",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": true,
+          "expr": "f2b_jail_banned_current{instance=~\"$instance\"}",
+          "interval": "",
+          "legendFormat": "{{jail}} ({{instance}})",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Fail2Ban Bans (Current)",
+      "transparent": true,
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "",
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": true,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "max": 1,
+          "min": 0,
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 5,
+        "w": 12,
+        "x": 0,
+        "y": 22
+      },
+      "id": 203,
+      "options": {
+        "legend": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "displayMode": "table",
+          "placement": "right",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "pluginVersion": "8.2.1",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": true,
+          "expr": "f2b_up{instance=~\"$instance\"}",
+          "interval": "",
+          "legendFormat": "Up ({{instance}})",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Fail2Ban Up",
+      "transparent": true,
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "${DS_PROMETHEUS}"
+      },
+      "description": "",
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "palette-classic"
+          },
+          "custom": {
+            "axisCenteredZero": false,
+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
+            "barAlignment": 0,
+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
+              "legend": false,
+              "tooltip": false,
+              "viz": false
+            },
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": true,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "max": 1,
+          "min": 0,
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 5,
+        "w": 12,
+        "x": 12,
+        "y": 22
+      },
+      "id": 204,
+      "options": {
+        "legend": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "displayMode": "table",
+          "placement": "right",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "single",
+          "sort": "none"
+        }
+      },
+      "pluginVersion": "8.2.1",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "editorMode": "code",
+          "exemplar": true,
+          "expr": "f2b_errors{instance=~\"$instance\"}",
+          "interval": "",
+          "legendFormat": "{{type}} ({{instance}})",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "Fail2Ban Exporter Errors",
+      "transparent": true,
+      "type": "timeseries"
+    }
+  ],
+  "refresh": "30s",
+  "schemaVersion": 37,
+  "style": "dark",
+  "tags": [],
+  "templating": {
+    "list": [
+      {
+        "current": {
+          "selected": false,
+          "text": "Prometheus",
+          "value": "Prometheus"
+        },
+        "hide": 0,
+        "includeAll": false,
+        "label": "Data Source",
+        "multi": false,
+        "name": "DataSource",
+        "options": [],
+        "query": "prometheus",
+        "queryValue": "",
+        "refresh": 1,
+        "regex": "",
+        "skipUrlSync": false,
+        "type": "datasource"
+      },
+      {
+        "current": {},
+        "datasource": {
+          "type": "prometheus",
+          "uid": "${DS_PROMETHEUS}"
+        },
+        "definition": "f2b_up",
+        "description": "Select which instance(s) to show",
+        "hide": 0,
+        "includeAll": false,
+        "label": "Instance",
+        "multi": true,
+        "name": "instance",
+        "options": [],
+        "query": {
+          "query": "f2b_up",
+          "refId": "StandardVariableQuery"
+        },
+        "refresh": 1,
+        "regex": "/.*instance=\"([^\"]+)\"/",
+        "skipUrlSync": false,
+        "sort": 0,
+        "type": "query"
+      }
+    ]
+  },
+  "time": {
+    "from": "now-6h",
+    "to": "now"
+  },
+  "timepicker": {},
+  "timezone": "",
+  "title": "F2B",
+  "uid": "cTkH9AT7z",
+  "version": 3,
+  "weekStart": ""
+}

_examples/systemd/README.md

@@ -0,0 +1,7 @@
+# Systemd
+
+The `.service` file in this directory should be copied to the `/etc/systemd/system/` folder.
+- It expects the binary file to be installed at `/usr/sbin/fail2ban_exporter`.
+- It expects a user named `fail2ban_exporter` to exist. This user should not have a shell or any special privileges aside from read-access to the fail2ban socket file.
+
+The `ExecStart` line can be modified to add any custom CLI flags.

_examples/systemd/fail2ban_exporter.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=Fail2Ban Exporter
+
+[Service]
+User=fail2ban_exporter
+ExecStart=/usr/sbin/fail2ban_exporter
+
+[Install]
+WantedBy=multi-user.target

auth/basic.go

@@ -0,0 +1,29 @@
+package auth
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func NewBasicAuthProvider(username, password string) AuthProvider {
+	return &basicAuthProvider{
+		hashedAuth: encodeBasicAuth(username, password),
+	}
+}
+
+type basicAuthProvider struct {
+	hashedAuth string
+}
+
+func (p *basicAuthProvider) IsAllowed(request *http.Request) bool {
+	username, password, ok := request.BasicAuth()
+	if !ok {
+		return false
+	}
+	requestAuth := encodeBasicAuth(username, password)
+	return p.hashedAuth == requestAuth
+}
+
+func encodeBasicAuth(username, password string) string {
+	return HashString(fmt.Sprintf("%s:%s", username, password))
+}

auth/basic_test.go

@@ -0,0 +1,53 @@
+package auth
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func Test_GIVEN_BasicAuthSet_WHEN_CallingIsAllowedWithCorrectCreds_THEN_TrueReturned(t *testing.T) {
+	// assemble
+	username := "u1"
+	password := HashString("abc")
+	request := httptest.NewRequest(http.MethodGet, "http://example.com", nil)
+	request.SetBasicAuth(username, password)
+	provider := NewBasicAuthProvider(username, password)
+
+	// act
+	result := provider.IsAllowed(request)
+
+	// assert
+	if !result {
+		t.Errorf("expected request to be allowed, but failed")
+	}
+}
+
+func Test_GIVEN_BasicAuthSet_WHEN_CallingIsAllowedWithoutCreds_THEN_FalseReturned(t *testing.T) {
+	// assemble
+	request := httptest.NewRequest(http.MethodGet, "http://example.com", nil)
+	provider := NewBasicAuthProvider("u1", "p1")
+
+	// act
+	result := provider.IsAllowed(request)
+
+	// assert
+	if result {
+		t.Errorf("expected request to be denied, but was allowed")
+	}
+}
+
+func Test_GIVEN_BasicAuthSet_WHEN_CallingIsAllowedWithWrongCreds_THEN_FalseReturned(t *testing.T) {
+	// assemble
+	request := httptest.NewRequest(http.MethodGet, "http://example.com", nil)
+	request.SetBasicAuth("wrong", "pw")
+	provider := NewBasicAuthProvider("u1", "p1")
+
+	// act
+	result := provider.IsAllowed(request)
+
+	// assert
+	if result {
+		t.Errorf("expected request to be denied, but was allowed")
+	}
+}

auth/empty.go

@@ -0,0 +1,14 @@
+package auth
+
+import "net/http"
+
+func NewEmptyAuthProvider() AuthProvider {
+	return &emptyAuthProvider{}
+}
+
+type emptyAuthProvider struct {
+}
+
+func (p *emptyAuthProvider) IsAllowed(request *http.Request) bool {
+	return true
+}

auth/empty_test.go

@@ -0,0 +1,36 @@
+package auth
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func Test_GIVEN_EmptyAuth_WHEN_CallingIsAllowedWithoutAuth_THEN_TrueReturned(t *testing.T) {
+	// assemble
+	request := httptest.NewRequest(http.MethodGet, "http://example.com", nil)
+	provider := NewEmptyAuthProvider()
+
+	// act
+	response := provider.IsAllowed(request)
+
+	// assert
+	if !response {
+		t.Errorf("expected request to be allowed, but failed")
+	}
+}
+
+func Test_GIVEN_EmptyAuth_WHEN_CallingIsAllowedWithAuth_THEN_TrueReturned(t *testing.T) {
+	// assemble
+	request := httptest.NewRequest(http.MethodGet, "http://example.com", nil)
+	request.SetBasicAuth("user", "pass")
+	provider := NewEmptyAuthProvider()
+
+	// act
+	response := provider.IsAllowed(request)
+
+	// assert
+	if !response {
+		t.Errorf("expected request to be allowed, but failed")
+	}
+}

auth/hash.go

@@ -0,0 +1,18 @@
+package auth
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+)
+
+func hash(data []byte) []byte {
+	if len(data) == 0 {
+		return []byte{}
+	}
+	b := sha256.Sum256(data)
+	return b[:]
+}
+
+func HashString(data string) string {
+	return hex.EncodeToString(hash([]byte(data)))
+}

auth/hash_test.go

@@ -0,0 +1,26 @@
+package auth
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestHashString(t *testing.T) {
+	tests := []struct {
+		name string
+		args string
+		want string
+	}{
+		{"Happy path #1", "123", "a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3"},
+		{"Happy path #2", "hello world", "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"},
+		{"Happy path #3", "H3Ll0_W0RLD", "d58a27fe9a6e73a1d8a67189fb8acace047e7a1a795276a0056d3717ad61bd0e"},
+		{"Blank string", "", ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := HashString(tt.args); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("HashString() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

auth/provider.go

@@ -0,0 +1,9 @@
+package auth
+
+import (
+	"net/http"
+)
+
+type AuthProvider interface {
+	IsAllowed(*http.Request) bool
+}

cfg/cfg.go

@@ -0,0 +1,84 @@
+package cfg
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/alecthomas/kong"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/auth"
+)
+
+var cliStruct struct {
+	VersionMode          bool   `name:"version" short:"v" help:"Show version info and exit"`
+	DryRunMode           bool   `name:"dry-run" help:"Attempt to connect to the fail2ban socket then exit before starting the server"`
+	ServerAddress        string `name:"web.listen-address" env:"F2B_WEB_LISTEN_ADDRESS" help:"Address to use for the metrics server" default:"${default_address}"`
+	F2bSocketPath        string `name:"collector.f2b.socket" env:"F2B_COLLECTOR_SOCKET" help:"Path to the fail2ban server socket" default:"${default_socket}"`
+	ExitOnSocketError    bool   `name:"collector.f2b.exit-on-socket-connection-error" env:"F2B_EXIT_ON_SOCKET_CONN_ERROR" help:"When set to true the exporter will immediately exit on a fail2ban socket connection error"`
+	TextFileExporterPath string `name:"collector.textfile.directory" env:"F2B_COLLECTOR_TEXT_PATH" help:"Directory to read text files with metrics from"`
+	BasicAuthUser        string `name:"web.basic-auth.username" env:"F2B_WEB_BASICAUTH_USER" help:"Username to use to protect endpoints with basic auth"`
+	BasicAuthPass        string `name:"web.basic-auth.password" env:"F2B_WEB_BASICAUTH_PASS" help:"Password to use to protect endpoints with basic auth"`
+}
+
+func Parse() *AppSettings {
+	ctx := kong.Parse(
+		&cliStruct,
+		kong.Vars{
+			"default_socket":  "/var/run/fail2ban/fail2ban.sock",
+			"default_address": ":9191",
+		},
+		kong.Name("fail2ban_exporter"),
+		kong.Description("🚀 Export prometheus metrics from a running Fail2Ban instance"),
+		kong.UsageOnError(),
+	)
+
+	validateFlags(ctx)
+	settings := &AppSettings{
+		VersionMode:           cliStruct.VersionMode,
+		DryRunMode:            cliStruct.DryRunMode,
+		MetricsAddress:        cliStruct.ServerAddress,
+		Fail2BanSocketPath:    cliStruct.F2bSocketPath,
+		FileCollectorPath:     cliStruct.TextFileExporterPath,
+		ExitOnSocketConnError: cliStruct.ExitOnSocketError,
+		AuthProvider:          createAuthProvider(),
+	}
+	return settings
+}
+
+func createAuthProvider() auth.AuthProvider {
+	username := cliStruct.BasicAuthUser
+	password := cliStruct.BasicAuthPass
+
+	if len(username) == 0 && len(password) == 0 {
+		return auth.NewEmptyAuthProvider()
+	}
+	log.Print("basic auth enabled")
+	return auth.NewBasicAuthProvider(username, password)
+}
+
+func validateFlags(cliCtx *kong.Context) {
+	var flagsValid = true
+	var messages = []string{}
+	if !cliStruct.VersionMode {
+		if cliStruct.F2bSocketPath == "" {
+			messages = append(messages, "error: fail2ban socket path must not be blank")
+			flagsValid = false
+		}
+		if cliStruct.ServerAddress == "" {
+			messages = append(messages, "error: invalid server address, must not be blank")
+			flagsValid = false
+		}
+		if (len(cliStruct.BasicAuthUser) > 0) != (len(cliStruct.BasicAuthPass) > 0) {
+			messages = append(messages, "error: to enable basic auth both the username and the password must be provided")
+			flagsValid = false
+		}
+	}
+	if !flagsValid {
+		cliCtx.PrintUsage(false)
+		fmt.Println()
+		for i := 0; i < len(messages); i++ {
+			fmt.Println(messages[i])
+		}
+		os.Exit(1)
+	}
+}

cfg/settings.go

@@ -0,0 +1,13 @@
+package cfg
+
+import "gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/auth"
+
+type AppSettings struct {
+	VersionMode           bool
+	DryRunMode            bool
+	MetricsAddress        string
+	Fail2BanSocketPath    string
+	FileCollectorPath     string
+	AuthProvider          auth.AuthProvider
+	ExitOnSocketConnError bool
+}

collector/f2b/collector.go

@@ -0,0 +1,76 @@
+package f2b
+
+import (
+	"log"
+	"os"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/cfg"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/socket"
+)
+
+type Collector struct {
+	socketPath                 string
+	exporterVersion            string
+	lastError                  error
+	socketConnectionErrorCount int
+	socketRequestErrorCount    int
+	exitOnSocketConnError      bool
+}
+
+func NewExporter(appSettings *cfg.AppSettings, exporterVersion string) *Collector {
+	log.Printf("reading fail2ban metrics from socket file: %s", appSettings.Fail2BanSocketPath)
+	printFail2BanServerVersion(appSettings.Fail2BanSocketPath)
+	return &Collector{
+		socketPath:                 appSettings.Fail2BanSocketPath,
+		exporterVersion:            exporterVersion,
+		lastError:                  nil,
+		socketConnectionErrorCount: 0,
+		socketRequestErrorCount:    0,
+		exitOnSocketConnError:      appSettings.ExitOnSocketConnError,
+	}
+}
+
+func (c *Collector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- metricServerUp
+	ch <- metricJailCount
+	ch <- metricJailFailedCurrent
+	ch <- metricJailFailedTotal
+	ch <- metricJailBannedCurrent
+	ch <- metricJailBannedTotal
+	ch <- metricErrorCount
+}
+
+func (c *Collector) Collect(ch chan<- prometheus.Metric) {
+	s, err := socket.ConnectToSocket(c.socketPath)
+	if err != nil {
+		log.Printf("error opening socket: %v", err)
+		c.socketConnectionErrorCount++
+		if c.exitOnSocketConnError {
+			os.Exit(1)
+		}
+	} else {
+		defer s.Close()
+	}
+
+	c.collectServerUpMetric(ch, s)
+	if err == nil && s != nil {
+		c.collectJailMetrics(ch, s)
+		c.collectVersionMetric(ch, s)
+	}
+	c.collectErrorCountMetric(ch)
+}
+
+func printFail2BanServerVersion(socketPath string) {
+	s, err := socket.ConnectToSocket(socketPath)
+	if err != nil {
+		log.Printf("error connecting to socket: %v", err)
+	} else {
+		version, err := s.GetServerVersion()
+		if err != nil {
+			log.Printf("error interacting with socket: %v", err)
+		} else {
+			log.Printf("successfully connected to fail2ban socket! fail2ban version: %s", version)
+		}
+	}
+}

collector/f2b/socket.go

@@ -0,0 +1,179 @@
+package f2b
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/socket"
+	"log"
+)
+
+const (
+	namespace = "f2b"
+)
+
+var (
+	metricErrorCount = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "errors"),
+		"Number of errors found since startup",
+		[]string{"type"}, nil,
+	)
+	metricServerUp = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "up"),
+		"Check if the fail2ban server is up",
+		nil, nil,
+	)
+	metricJailCount = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "jail_count"),
+		"Number of defined jails",
+		nil, nil,
+	)
+	metricJailFailedCurrent = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "jail_failed_current"),
+		"Number of current failures on this jail's filter",
+		[]string{"jail"}, nil,
+	)
+	metricJailFailedTotal = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "jail_failed_total"),
+		"Number of total failures on this jail's filter",
+		[]string{"jail"}, nil,
+	)
+	metricJailBannedCurrent = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "jail_banned_current"),
+		"Number of IPs currently banned in this jail",
+		[]string{"jail"}, nil,
+	)
+	metricJailBannedTotal = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "jail_banned_total"),
+		"Total number of IPs banned by this jail (includes expired bans)",
+		[]string{"jail"}, nil,
+	)
+	metricJailBanTime = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "config", "jail_ban_time"),
+		"How long an IP is banned for in this jail (in seconds)",
+		[]string{"jail"}, nil,
+	)
+	metricJailFindTime = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "config", "jail_find_time"),
+		"How far back will the filter look for failures in this jail (in seconds)",
+		[]string{"jail"}, nil,
+	)
+	metricJailMaxRetry = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "config", "jail_max_retries"),
+		"The number of failures allowed until the IP is banned by this jail",
+		[]string{"jail"}, nil,
+	)
+	metricVersionInfo = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "version"),
+		"Version of the exporter and fail2ban server",
+		[]string{"exporter", "fail2ban"}, nil,
+	)
+)
+
+func (c *Collector) collectErrorCountMetric(ch chan<- prometheus.Metric) {
+	ch <- prometheus.MustNewConstMetric(
+		metricErrorCount, prometheus.CounterValue, float64(c.socketConnectionErrorCount), "socket_conn",
+	)
+	ch <- prometheus.MustNewConstMetric(
+		metricErrorCount, prometheus.CounterValue, float64(c.socketRequestErrorCount), "socket_req",
+	)
+}
+
+func (c *Collector) collectServerUpMetric(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket) {
+	var serverUp float64 = 0
+	if s != nil {
+		pingSuccess, err := s.Ping()
+		if err != nil {
+			c.socketRequestErrorCount++
+			log.Print(err)
+		}
+		if err == nil && pingSuccess {
+			serverUp = 1
+		}
+	}
+	ch <- prometheus.MustNewConstMetric(
+		metricServerUp, prometheus.GaugeValue, serverUp,
+	)
+}
+
+func (c *Collector) collectJailMetrics(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket) {
+	jails, err := s.GetJails()
+	var count float64 = 0
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Print(err)
+	}
+	if err == nil {
+		count = float64(len(jails))
+	}
+	ch <- prometheus.MustNewConstMetric(
+		metricJailCount, prometheus.GaugeValue, count,
+	)
+
+	for i := range jails {
+		c.collectJailStatsMetric(ch, s, jails[i])
+		c.collectJailConfigMetrics(ch, s, jails[i])
+	}
+}
+
+func (c *Collector) collectJailStatsMetric(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket, jail string) {
+	stats, err := s.GetJailStats(jail)
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get stats for jail %s: %v", jail, err)
+		return
+	}
+
+	ch <- prometheus.MustNewConstMetric(
+		metricJailFailedCurrent, prometheus.GaugeValue, float64(stats.FailedCurrent), jail,
+	)
+	ch <- prometheus.MustNewConstMetric(
+		metricJailFailedTotal, prometheus.GaugeValue, float64(stats.FailedTotal), jail,
+	)
+	ch <- prometheus.MustNewConstMetric(
+		metricJailBannedCurrent, prometheus.GaugeValue, float64(stats.BannedCurrent), jail,
+	)
+	ch <- prometheus.MustNewConstMetric(
+		metricJailBannedTotal, prometheus.GaugeValue, float64(stats.BannedTotal), jail,
+	)
+}
+
+func (c *Collector) collectJailConfigMetrics(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket, jail string) {
+	banTime, err := s.GetJailBanTime(jail)
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get ban time for jail %s: %v", jail, err)
+	} else {
+		ch <- prometheus.MustNewConstMetric(
+			metricJailBanTime, prometheus.GaugeValue, float64(banTime), jail,
+		)
+	}
+	findTime, err := s.GetJailFindTime(jail)
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get find time for jail %s: %v", jail, err)
+	} else {
+		ch <- prometheus.MustNewConstMetric(
+			metricJailFindTime, prometheus.GaugeValue, float64(findTime), jail,
+		)
+	}
+	maxRetry, err := s.GetJailMaxRetries(jail)
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get max retries for jail %s: %v", jail, err)
+	} else {
+		ch <- prometheus.MustNewConstMetric(
+			metricJailMaxRetry, prometheus.GaugeValue, float64(maxRetry), jail,
+		)
+	}
+}
+
+func (c *Collector) collectVersionMetric(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket) {
+	fail2banVersion, err := s.GetServerVersion()
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get fail2ban server version: %v", err)
+	}
+
+	ch <- prometheus.MustNewConstMetric(
+		metricVersionInfo, prometheus.GaugeValue, float64(1), c.exporterVersion, fail2banVersion,
+	)
+}

collector/textfile/collector.go

@@ -0,0 +1,48 @@
+package textfile
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/cfg"
+	"log"
+)
+
+type Collector struct {
+	enabled    bool
+	folderPath string
+	fileMap    map[string]*fileData
+}
+
+type fileData struct {
+	readErrors   int
+	fileName     string
+	fileContents []byte
+}
+
+func NewCollector(appSettings *cfg.AppSettings) *Collector {
+	collector := &Collector{
+		enabled:    appSettings.FileCollectorPath != "",
+		folderPath: appSettings.FileCollectorPath,
+		fileMap:    make(map[string]*fileData),
+	}
+	if collector.enabled {
+		log.Printf("reading textfile metrics from: %s", collector.folderPath)
+	}
+	return collector
+}
+
+func (c *Collector) Describe(ch chan<- *prometheus.Desc) {
+	if c.enabled {
+		ch <- metricReadError
+	}
+}
+
+func (c *Collector) Collect(ch chan<- prometheus.Metric) {
+	if c.enabled {
+		c.collectFileContents()
+		c.collectFileErrors(ch)
+	}
+}
+
+func (c *Collector) appendErrorForPath(path string) {
+	c.fileMap[path].readErrors++
+}

collector/textfile/file.go

@@ -0,0 +1,56 @@
+package textfile
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const namespace = "textfile"
+
+var (
+	metricReadError = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "error"),
+		"Checks for errors while reading text files",
+		[]string{"path"}, nil,
+	)
+)
+
+func (c *Collector) collectFileContents() {
+	files, err := os.ReadDir(c.folderPath)
+	if err != nil {
+		log.Printf("error reading directory '%s': %v", c.folderPath, err)
+		return
+	}
+
+	for _, file := range files {
+		fileName := file.Name()
+		if !strings.HasSuffix(strings.ToLower(fileName), ".prom") {
+			continue
+		}
+		c.fileMap[fileName] = &fileData{
+			readErrors: 0,
+			fileName:   fileName,
+		}
+
+		fullPath := filepath.Join(c.folderPath, fileName)
+		content, err := os.ReadFile(fullPath)
+		if err != nil {
+			c.appendErrorForPath(fileName)
+			log.Printf("error reading contents of file '%s': %v", fileName, err)
+		}
+
+		c.fileMap[fileName].fileContents = content
+	}
+}
+
+func (c *Collector) collectFileErrors(ch chan<- prometheus.Metric) {
+	for _, f := range c.fileMap {
+		ch <- prometheus.MustNewConstMetric(
+			metricReadError, prometheus.GaugeValue, float64(f.readErrors), f.fileName,
+		)
+	}
+}

collector/textfile/writer.go

@@ -0,0 +1,20 @@
+package textfile
+
+import (
+	"log"
+	"net/http"
+)
+
+func (c *Collector) WriteTextFileMetrics(w http.ResponseWriter, r *http.Request) {
+	if !c.enabled {
+		return
+	}
+
+	for _, f := range c.fileMap {
+		_, err := w.Write(f.fileContents)
+		if err != nil {
+			c.appendErrorForPath(f.fileName)
+			log.Printf("error writing file contents to response writer '%s': %v", f.fileName, err)
+		}
+	}
+}

exporter.go

@@ -1,7 +1,66 @@
 package main
 
-import "log"
+import (
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/cfg"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/collector/f2b"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/collector/textfile"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/server"
+)
+
+var (
+	version = "dev"
+	commit  = "none"
+	date    = "unknown"
+	builtBy = "unknown"
+)
+
+func printAppVersion() {
+	fmt.Println(version)
+	fmt.Printf("    build date:  %s\r\n    commit hash: %s\r\n    built by:    %s\r\n", date, commit, builtBy)
+}
 
 func main() {
-	log.Println("Not yet implemented")
+	appSettings := cfg.Parse()
+	if appSettings.VersionMode {
+		printAppVersion()
+		return
+	}
+
+	handleGracefulShutdown()
+	log.Printf("fail2ban exporter version %s", version)
+	log.Printf("starting server at %s", appSettings.MetricsAddress)
+
+	f2bCollector := f2b.NewExporter(appSettings, version)
+	prometheus.MustRegister(f2bCollector)
+
+	textFileCollector := textfile.NewCollector(appSettings)
+	prometheus.MustRegister(textFileCollector)
+
+	if !appSettings.DryRunMode {
+		svrErr := server.StartServer(appSettings, textFileCollector)
+		err := <-svrErr
+		log.Fatal(err)
+	} else {
+		log.Print("running in dry-run mode - exiting")
+	}
+}
+
+func handleGracefulShutdown() {
+	var signals = make(chan os.Signal, 1)
+
+	signal.Notify(signals, syscall.SIGTERM)
+	signal.Notify(signals, syscall.SIGINT)
+
+	go func() {
+		sig := <-signals
+		log.Printf("caught signal: %+v", sig)
+		os.Exit(0)
+	}()
 }

go.mod

@@ -1,3 +1,22 @@
-module fail2ban-prometheus-exporter
+module gitlab.com/hectorjsmith/fail2ban-prometheus-exporter
 
-go 1.15
+go 1.20
+
+require (
+	github.com/alecthomas/kong v0.7.1
+	github.com/kisielk/og-rek v1.2.0
+	github.com/nlpodyssey/gopickle v0.2.0
+	github.com/prometheus/client_golang v1.16.0
+)
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
+	github.com/prometheus/client_model v0.4.0 // indirect
+	github.com/prometheus/common v0.44.0 // indirect
+	github.com/prometheus/procfs v0.11.0 // indirect
+	golang.org/x/sys v0.9.0 // indirect
+	google.golang.org/protobuf v1.30.0 // indirect
+)

go.sum

@@ -0,0 +1,38 @@
+github.com/alecthomas/assert/v2 v2.1.0 h1:tbredtNcQnoSd3QBhQWI7QZ3XHOVkw1Moklp2ojoH/0=
+github.com/alecthomas/kong v0.7.1 h1:azoTh0IOfwlAX3qN9sHWTxACE2oV8Bg2gAwBsMwDQY4=
+github.com/alecthomas/kong v0.7.1/go.mod h1:n1iCIO2xS46oE8ZfYCNDqdR0b0wZNrXAIAqro/2132U=
+github.com/alecthomas/repr v0.1.0 h1:ENn2e1+J3k09gyj2shc0dHr/yjaWSHRlrJ4DPMevDqE=
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
+github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
+github.com/kisielk/og-rek v1.2.0 h1:CTvDIin+YnetsSQAYbe+QNAxXU3B50C5hseEz8xEoJw=
+github.com/kisielk/og-rek v1.2.0/go.mod h1:6ihsOSzSAxR/65S3Bn9zNihoEqRquhDQZ2c6I2+MG3c=
+github.com/matttproud/golang_protobuf_extensions v1.0.4 h1:mmDVorXM7PCGKw94cs5zkfA9PSy5pEvNWRP0ET0TIVo=
+github.com/matttproud/golang_protobuf_extensions v1.0.4/go.mod h1:BSXmuO+STAnVfrANrmjBb36TMTDstsz7MSK+HVaYKv4=
+github.com/nlpodyssey/gopickle v0.2.0 h1:4naD2DVylYJupQLbCQFdwo6yiXEmPyp+0xf5MVlrBDY=
+github.com/nlpodyssey/gopickle v0.2.0/go.mod h1:YIUwjJ2O7+vnBsxUN+MHAAI3N+adqEGiw+nDpwW95bY=
+github.com/prometheus/client_golang v1.16.0 h1:yk/hx9hDbrGHovbci4BY+pRMfSuuat626eFsHb7tmT8=
+github.com/prometheus/client_golang v1.16.0/go.mod h1:Zsulrv/L9oM40tJ7T815tM89lFEugiJ9HzIqaAx4LKc=
+github.com/prometheus/client_model v0.4.0 h1:5lQXD3cAg1OXBf4Wq03gTrXHeaV0TQvGfUooCfx1yqY=
+github.com/prometheus/client_model v0.4.0/go.mod h1:oMQmHW1/JoDwqLtg57MGgP/Fb1CJEYF2imWWhWtMkYU=
+github.com/prometheus/common v0.44.0 h1:+5BrQJwiBB9xsMygAB3TNvpQKOwlkc25LbISbrdOOfY=
+github.com/prometheus/common v0.44.0/go.mod h1:ofAIvZbQ1e/nugmZGz4/qCb9Ap1VoSTIO7x0VV9VvuY=
+github.com/prometheus/procfs v0.11.0 h1:5EAgkfkMl659uZPbe9AS2N68a7Cc1TJbPEuGzFuRbyk=
+github.com/prometheus/procfs v0.11.0/go.mod h1:nwNm2aOCAYw8uTR/9bWRREkZFxAUcWzPHWJq+XBB/FM=
+golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.9.0 h1:KS/R3tvhPqvJvwcKfnBHJwwthS11LRhmM5D59eEXa0s=
+golang.org/x/sys v0.9.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
+google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=

server/auth.go

@@ -0,0 +1,17 @@
+package server
+
+import (
+	"net/http"
+
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/auth"
+)
+
+func AuthMiddleware(handlerFunc http.HandlerFunc, authProvider auth.AuthProvider) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if authProvider.IsAllowed(r) {
+			handlerFunc.ServeHTTP(w, r)
+		} else {
+			w.WriteHeader(http.StatusUnauthorized)
+		}
+	}
+}

server/auth_test.go

@@ -0,0 +1,46 @@
+package server
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+type testAuthProvider struct {
+	match bool
+}
+
+func (p testAuthProvider) IsAllowed(request *http.Request) bool {
+	return p.match
+}
+
+func newTestRequest() *http.Request {
+	return httptest.NewRequest(http.MethodGet, "http://example.com", nil)
+}
+
+func executeAuthMiddlewareTest(t *testing.T, authMatches bool, expectedCode int, expectedCallCount int) {
+	callCount := 0
+	testHandler := func(w http.ResponseWriter, r *http.Request) {
+		callCount++
+	}
+
+	handler := AuthMiddleware(testHandler, testAuthProvider{match: authMatches})
+	recorder := httptest.NewRecorder()
+	request := newTestRequest()
+	handler.ServeHTTP(recorder, request)
+
+	if recorder.Code != expectedCode {
+		t.Errorf("statusCode = %v, want %v", recorder.Code, expectedCode)
+	}
+	if callCount != expectedCallCount {
+		t.Errorf("callCount = %v, want %v", callCount, expectedCallCount)
+	}
+}
+
+func Test_GIVEN_MatchingBasicAuth_WHEN_MethodCalled_THEN_RequestProcessed(t *testing.T) {
+	executeAuthMiddlewareTest(t, true, http.StatusOK, 1)
+}
+
+func Test_GIVEN_NonMatchingBasicAuth_WHEN_MethodCalled_THEN_RequestRejected(t *testing.T) {
+	executeAuthMiddlewareTest(t, false, http.StatusUnauthorized, 0)
+}

server/handler.go

@@ -0,0 +1,33 @@
+package server
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/collector/textfile"
+)
+
+const (
+	metricsPath = "/metrics"
+)
+
+func rootHtmlHandler(w http.ResponseWriter, r *http.Request) {
+	_, err := w.Write([]byte(
+		`<html>
+			<head><title>Fail2Ban Exporter</title></head>
+			<body>
+			<h1>Fail2Ban Exporter</h1>
+			<p><a href="` + metricsPath + `">Metrics</a></p>
+			</body>
+		</html>`))
+	if err != nil {
+		log.Printf("error handling root url: %v", err)
+		w.WriteHeader(http.StatusInternalServerError)
+	}
+}
+
+func metricHandler(w http.ResponseWriter, r *http.Request, collector *textfile.Collector) {
+	promhttp.Handler().ServeHTTP(w, r)
+	collector.WriteTextFileMetrics(w, r)
+}

server/server.go

@@ -0,0 +1,41 @@
+package server
+
+import (
+	"log"
+	"net/http"
+	"time"
+
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/cfg"
+	"gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/collector/textfile"
+)
+
+func StartServer(
+	appSettings *cfg.AppSettings,
+	textFileCollector *textfile.Collector,
+) chan error {
+	http.HandleFunc("/", AuthMiddleware(
+		rootHtmlHandler,
+		appSettings.AuthProvider,
+	))
+	http.HandleFunc(metricsPath, AuthMiddleware(
+		func(w http.ResponseWriter, r *http.Request) {
+			metricHandler(w, r, textFileCollector)
+		},
+		appSettings.AuthProvider,
+	))
+	log.Printf("metrics available at '%s'", metricsPath)
+
+	svrErr := make(chan error)
+	go func() {
+		httpServer := &http.Server{
+			Addr:              appSettings.MetricsAddress,
+			ReadHeaderTimeout: 10 * time.Second,
+			ReadTimeout:       10 * time.Second,
+			WriteTimeout:      10 * time.Second,
+			IdleTimeout:       30 * time.Second,
+		}
+		svrErr <- httpServer.ListenAndServe()
+	}()
+	log.Print("ready")
+	return svrErr
+}

socket/decoder.go

@@ -0,0 +1,8 @@
+package socket
+
+// Py_builtins_str is used by the pickle decoder to parse the server response into a format Go can understand
+type Py_builtins_str struct{}
+
+func (c Py_builtins_str) Call(args ...interface{}) (interface{}, error) {
+	return args[0], nil
+}

socket/fail2banSocket.go

@@ -0,0 +1,179 @@
+package socket
+
+import (
+	"fmt"
+	"github.com/kisielk/og-rek"
+	"github.com/nlpodyssey/gopickle/types"
+	"net"
+	"strings"
+)
+
+type Fail2BanSocket struct {
+	socket  net.Conn
+	encoder *ogórek.Encoder
+}
+
+type JailStats struct {
+	FailedCurrent int
+	FailedTotal   int
+	BannedCurrent int
+	BannedTotal   int
+}
+
+func ConnectToSocket(path string) (*Fail2BanSocket, error) {
+	c, err := net.Dial("unix", path)
+	if err != nil {
+		return nil, err
+	}
+	return &Fail2BanSocket{
+		socket:  c,
+		encoder: ogórek.NewEncoder(c),
+	}, nil
+}
+
+func (s *Fail2BanSocket) Close() error {
+	return s.socket.Close()
+}
+
+func (s *Fail2BanSocket) Ping() (bool, error) {
+	response, err := s.sendCommand([]string{pingCommand, "100"})
+	if err != nil {
+		return false, newConnectionError(pingCommand, err)
+	}
+
+	if t, ok := response.(*types.Tuple); ok {
+		if (*t)[1] == "pong" {
+			return true, nil
+		}
+		return false, fmt.Errorf("unexpected response data (expecting 'pong'): %s", (*t)[1])
+	}
+	return false, newBadFormatError(pingCommand, response)
+}
+
+func (s *Fail2BanSocket) GetJails() ([]string, error) {
+	response, err := s.sendCommand([]string{statusCommand})
+	if err != nil {
+		return nil, err
+	}
+
+	if lvl1, ok := response.(*types.Tuple); ok {
+		if lvl2, ok := lvl1.Get(1).(*types.List); ok {
+			if lvl3, ok := lvl2.Get(1).(*types.Tuple); ok {
+				if lvl4, ok := lvl3.Get(1).(string); ok {
+					splitJails := strings.Split(lvl4, ",")
+					return trimSpaceForAll(splitJails), nil
+				}
+			}
+		}
+	}
+	return nil, newBadFormatError(statusCommand, response)
+}
+
+func (s *Fail2BanSocket) GetJailStats(jail string) (JailStats, error) {
+	response, err := s.sendCommand([]string{statusCommand, jail})
+	if err != nil {
+		return JailStats{}, err
+	}
+
+	stats := JailStats{
+		FailedCurrent: -1,
+		FailedTotal:   -1,
+		BannedCurrent: -1,
+		BannedTotal:   -1,
+	}
+
+	if lvl1, ok := response.(*types.Tuple); ok {
+		if lvl2, ok := lvl1.Get(1).(*types.List); ok {
+			if filter, ok := lvl2.Get(0).(*types.Tuple); ok {
+				if filterLvl1, ok := filter.Get(1).(*types.List); ok {
+					if filterCurrentTuple, ok := filterLvl1.Get(0).(*types.Tuple); ok {
+						if filterCurrent, ok := filterCurrentTuple.Get(1).(int); ok {
+							stats.FailedCurrent = filterCurrent
+						}
+					}
+					if filterTotalTuple, ok := filterLvl1.Get(1).(*types.Tuple); ok {
+						if filterTotal, ok := filterTotalTuple.Get(1).(int); ok {
+							stats.FailedTotal = filterTotal
+						}
+					}
+				}
+			}
+			if actions, ok := lvl2.Get(1).(*types.Tuple); ok {
+				if actionsLvl1, ok := actions.Get(1).(*types.List); ok {
+					if actionsCurrentTuple, ok := actionsLvl1.Get(0).(*types.Tuple); ok {
+						if actionsCurrent, ok := actionsCurrentTuple.Get(1).(int); ok {
+							stats.BannedCurrent = actionsCurrent
+						}
+					}
+					if actionsTotalTuple, ok := actionsLvl1.Get(1).(*types.Tuple); ok {
+						if actionsTotal, ok := actionsTotalTuple.Get(1).(int); ok {
+							stats.BannedTotal = actionsTotal
+						}
+					}
+				}
+			}
+			return stats, nil
+		}
+	}
+	return stats, newBadFormatError(statusCommand, response)
+}
+
+func (s *Fail2BanSocket) GetJailBanTime(jail string) (int, error) {
+	command := fmt.Sprintf(banTimeCommandFmt, jail)
+	return s.sendSimpleIntCommand(command)
+}
+
+func (s *Fail2BanSocket) GetJailFindTime(jail string) (int, error) {
+	command := fmt.Sprintf(findTimeCommandFmt, jail)
+	return s.sendSimpleIntCommand(command)
+}
+
+func (s *Fail2BanSocket) GetJailMaxRetries(jail string) (int, error) {
+	command := fmt.Sprintf(maxRetriesCommandFmt, jail)
+	return s.sendSimpleIntCommand(command)
+}
+
+func (s *Fail2BanSocket) GetServerVersion() (string, error) {
+	response, err := s.sendCommand([]string{versionCommand})
+	if err != nil {
+		return "", err
+	}
+
+	if lvl1, ok := response.(*types.Tuple); ok {
+		if versionStr, ok := lvl1.Get(1).(string); ok {
+			return versionStr, nil
+		}
+	}
+	return "", newBadFormatError(versionCommand, response)
+}
+
+// sendSimpleIntCommand sends a command to the fail2ban socket and parses the response to extract an int.
+// This command assumes that the response data is in the format of `(d, d)` where `d` is a number.
+func (s *Fail2BanSocket) sendSimpleIntCommand(command string) (int, error) {
+	response, err := s.sendCommand(strings.Split(command, " "))
+	if err != nil {
+		return -1, err
+	}
+
+	if lvl1, ok := response.(*types.Tuple); ok {
+		if banTime, ok := lvl1.Get(1).(int); ok {
+			return banTime, nil
+		}
+	}
+	return -1, newBadFormatError(command, response)
+}
+
+func newBadFormatError(command string, data interface{}) error {
+	return fmt.Errorf("(%s) unexpected response format - cannot parse: %v", command, data)
+}
+
+func newConnectionError(command string, err error) error {
+	return fmt.Errorf("(%s) failed to send command through socket: %v", command, err)
+}
+
+func trimSpaceForAll(slice []string) []string {
+	for i := range slice {
+		slice[i] = strings.TrimSpace(slice[i])
+	}
+	return slice
+}

socket/protocol.go

@@ -0,0 +1,69 @@
+package socket
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"github.com/nlpodyssey/gopickle/pickle"
+)
+
+const (
+	commandTerminator    = "<F2B_END_COMMAND>"
+	pingCommand          = "ping"
+	statusCommand        = "status"
+	versionCommand       = "version"
+	banTimeCommandFmt    = "get %s bantime"
+	findTimeCommandFmt   = "get %s findtime"
+	maxRetriesCommandFmt = "get %s maxretry"
+	socketReadBufferSize = 1024
+)
+
+func (s *Fail2BanSocket) sendCommand(command []string) (interface{}, error) {
+	err := s.write(command)
+	if err != nil {
+		return nil, err
+	}
+	return s.read()
+}
+
+func (s *Fail2BanSocket) write(command []string) error {
+	err := s.encoder.Encode(command)
+	if err != nil {
+		return err
+	}
+	_, err = s.socket.Write([]byte(commandTerminator))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (s *Fail2BanSocket) read() (interface{}, error) {
+	reader := bufio.NewReader(s.socket)
+
+	data := []byte{}
+	for {
+		buf := make([]byte, socketReadBufferSize)
+		_, err := reader.Read(buf)
+		if err != nil {
+			return nil, err
+		}
+		data = append(data, buf...)
+		containsTerminator := bytes.Contains(data, []byte(commandTerminator))
+		if containsTerminator {
+			break
+		}
+	}
+
+	bufReader := bytes.NewReader(data)
+	unpickler := pickle.NewUnpickler(bufReader)
+
+	unpickler.FindClass = func(module, name string) (interface{}, error) {
+		if (module == "builtins" || module == "__builtin__") && name == "str" {
+			return &Py_builtins_str{}, nil
+		}
+		return nil, fmt.Errorf("class not found: " + module + " : " + name)
+	}
+
+	return unpickler.Load()
+}