feat: configure tool using environment variables (#17)

Replace CLI parsing functionality with the `kingpin` library to better support configuring the tool with environment variables. Add new environment variables to configure the tool. BREAKING CHANGE: CLI params now require two dashes instead of one (e.g. `--socket`)
2022-01-30 21:32:48 +00:00 · 2022-01-30 21:32:48 +00:00 · b7e317edbc
commit b7e317edbc
parent d92f7f79b6
5 changed files with 112 additions and 37 deletions
--- a/README.md
+++ b/README.md
@ -35,26 +35,39 @@ No additional runtime dependencies are required.
 Compiled binaries for various platforms are provided in each release.
 See the [releases page](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/-/releases) for more information.

-**Usage**
+**CLI Usage**
 ```
 $ fail2ban-prometheus-exporter -h
+usage: exporter [<flags>]

-  -collector.textfile
-        enable the textfile collector
-  -collector.textfile.directory string
-        directory to read text files with metrics from
-  -port int
-        port to use for the metrics server (default 9191)
-  -socket string
-        path to the fail2ban server socket
-  -version
-        show version info and exit
-  -web.basic-auth.password string
-        password to use to protect endpoints with basic auth
-  -web.basic-auth.username string
-        username to use to protect endpoints with basic auth
-  -web.listen-address string
-        address to use for the metrics server (default "0.0.0.0")
+Flags:
+  -h, --help                Show context-sensitive help (also try --help-long and --help-man).
+      --version             show version info and exit
+      --port=9191           port to use for the metrics server
+      --web.listen-address="0.0.0.0"
+                            address to use for the metrics server
+      --socket=""           path to the fail2ban server socket
+      --collector.textfile  enable the textfile collector
+      --collector.textfile.directory=""
+                            directory to read text files with metrics from
+      --web.basic-auth.username=""
+                            username to use to protect endpoints with basic auth
+      --web.basic-auth.password=""
+                            password to use to protect endpoints with basic auth
+```
+
+**Environment variables**
+
+The tool can also be configured using environment variables. Each CLI parameter has a corresponding environment variable.
+
+```
+F2B_COLLECTOR_SOCKET
+F2B_COLLECTOR_TEXT
+F2B_COLLECTOR_TEXT_PATH
+F2B_WEB_PORT
+F2B_WEB_LISTEN_ADDRESS
+F2B_WEB_BASICAUTH_USER
+F2B_WEB_BASICAUTH_PASS
 ```

 **Example**
--- a/docker/run.sh
+++ b/docker/run.sh
@ -15,6 +15,6 @@ fi
 # Start the exporter (use exec to support graceful shutdown)
 # Inspired by: https://akomljen.com/stopping-docker-containers-gracefully/
 exec /app/fail2ban-prometheus-exporter \
-    -socket "$socket_path" \
-    -collector.textfile=$textfile_enabled \
-    -collector.textfile.directory="$textfile_dir"
+    --socket "$socket_path" \
+    --collector.textfile=$textfile_enabled \
+    --collector.textfile.directory="$textfile_dir"
--- a/src/cfg/cfg.go
+++ b/src/cfg/cfg.go
@ -3,12 +3,20 @@ package cfg
 import (
 	"flag"
 	"fmt"
+	"gopkg.in/alecthomas/kingpin.v2"
 	"os"
 )

 const (
-	minServerPort = 1000
-	maxServerPort = 65535
+	minServerPort               = 1000
+	maxServerPort               = 65535
+	socketEnvName               = "F2B_COLLECTOR_SOCKET"
+	fileCollectorEnabledEnvName = "F2B_COLLECTOR_TEXT"
+	fileCollectorPathEnvName    = "F2B_COLLECTOR_TEXT_PATH"
+	portEnvName                 = "F2B_WEB_PORT"
+	addressEnvName              = "F2B_WEB_LISTEN_ADDRESS"
+	basicAuthUserEnvName        = "F2B_WEB_BASICAUTH_USER"
+	basicAuthPassEnvName        = "F2B_WEB_BASICAUTH_PASS"
 )

 type AppSettings struct {
@ -21,24 +29,67 @@ type AppSettings struct {
 	BasicAuthProvider    *hashedBasicAuth
 }

+func init() {
+	kingpin.HelpFlag.Short('h')
+}
+
 func Parse() *AppSettings {
-	var rawBasicAuthUsername string
-	var rawBasicAuthPassword string
+	settings := &AppSettings{}
+	readParamsFromCli(settings)
+	settings.validateFlags()
+	return settings
+}

-	appSettings := &AppSettings{}
-	flag.BoolVar(&appSettings.VersionMode, "version", false, "show version info and exit")
-	flag.StringVar(&appSettings.MetricsAddress, "web.listen-address", "0.0.0.0", "address to use for the metrics server")
-	flag.IntVar(&appSettings.MetricsPort, "port", 9191, "port to use for the metrics server")
-	flag.StringVar(&appSettings.Fail2BanSocketPath, "socket", "", "path to the fail2ban server socket")
-	flag.BoolVar(&appSettings.FileCollectorEnabled, "collector.textfile", false, "enable the textfile collector")
-	flag.StringVar(&appSettings.FileCollectorPath, "collector.textfile.directory", "", "directory to read text files with metrics from")
-	flag.StringVar(&rawBasicAuthUsername, "web.basic-auth.username", "", "username to use to protect endpoints with basic auth")
-	flag.StringVar(&rawBasicAuthPassword, "web.basic-auth.password", "", "password to use to protect endpoints with basic auth")
+func readParamsFromCli(settings *AppSettings) {
+	versionMode := kingpin.
+		Flag("version", "show version info and exit").
+		Default("false").
+		Bool()
+	socketPath := kingpin.
+		Flag("socket", "path to the fail2ban server socket").
+		Default("").
+		Envar(socketEnvName).
+		String()
+	fileCollectorEnabled := kingpin.
+		Flag("collector.textfile", "enable the textfile collector").
+		Default("false").
+		Envar(fileCollectorEnabledEnvName).
+		Bool()
+	fileCollectorPath := kingpin.
+		Flag("collector.textfile.directory", "directory to read text files with metrics from").
+		Default("").
+		Envar(fileCollectorPathEnvName).
+		String()
+	port := kingpin.
+		Flag("port", "port to use for the metrics server").
+		Default("9191").
+		Envar(portEnvName).
+		Int()
+	address := kingpin.
+		Flag("web.listen-address", "address to use for the metrics server").
+		Default("0.0.0.0").
+		Envar(addressEnvName).
+		String()
+	rawBasicAuthUsername := kingpin.
+		Flag("web.basic-auth.username", "username to use to protect endpoints with basic auth").
+		Default("").
+		Envar(basicAuthUserEnvName).
+		String()
+	rawBasicAuthPassword := kingpin.
+		Flag("web.basic-auth.password", "password to use to protect endpoints with basic auth").
+		Default("").
+		Envar(basicAuthPassEnvName).
+		String()

-	flag.Parse()
-	appSettings.setBasicAuthValues(rawBasicAuthUsername, rawBasicAuthPassword)
-	appSettings.validateFlags()
-	return appSettings
+	settings.VersionMode = *versionMode
+	settings.MetricsPort = *port
+	settings.MetricsAddress = *address
+	settings.Fail2BanSocketPath = *socketPath
+	settings.FileCollectorEnabled = *fileCollectorEnabled
+	settings.FileCollectorPath = *fileCollectorPath
+	settings.setBasicAuthValues(*rawBasicAuthUsername, *rawBasicAuthPassword)
+
+	kingpin.Parse()
 }

 func (settings *AppSettings) setBasicAuthValues(rawUsername, rawPassword string) {
--- a/src/go.mod
+++ b/src/go.mod
@ -6,4 +6,5 @@ require (
 	github.com/kisielk/og-rek v1.1.0
 	github.com/nlpodyssey/gopickle v0.1.0
 	github.com/prometheus/client_golang v1.9.0
+	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 )
--- a/src/go.sum
+++ b/src/go.sum
@ -7,9 +7,11 @@ github.com/Shopify/toxiproxy v2.1.4+incompatible/go.mod h1:OXgGpZ6Cli1/URJOF1DMx
 github.com/VividCortex/gohistogram v1.0.0/go.mod h1:Pf5mBqqDxYaXu3hDrrU+w6nw50o/4+TcAqDqk/vUH7g=
 github.com/afex/hystrix-go v0.0.0-20180502004556-fa1af6a1f4f5/go.mod h1:SkGFH1ia65gfNATL8TAiHDNxPzPdmEL5uirI2Uyuz6c=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 h1:JYp7IbQjafoB+tBA3gMyHYHrpOtNuDiK/uB5uXxq5wM=
 github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
+github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d h1:UQZhZ2O0vMHr2cI+DC1Mbh0TJxzA3RcLoMsFw+aXw7E=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
 github.com/apache/thrift v0.12.0/go.mod h1:cp2SuWMxlEZw2r+iP2GNCdIi4C1qmUzdZFSVb+bacwQ=
 github.com/apache/thrift v0.13.0/go.mod h1:cp2SuWMxlEZw2r+iP2GNCdIi4C1qmUzdZFSVb+bacwQ=
@ -40,6 +42,7 @@ github.com/coreos/pkg v0.0.0-20160727233714-3ac0863d7acf/go.mod h1:E3G3o1h8I7cfc
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/dustin/go-humanize v0.0.0-20171111073723-bb3d318650d4/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
@ -142,8 +145,10 @@ github.com/kisielk/og-rek v1.1.0/go.mod h1:6ihsOSzSAxR/65S3Bn9zNihoEqRquhDQZ2c6I
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/lightstep/lightstep-tracer-common/golang/gogo v0.0.0-20190605223551-bc2310a04743/go.mod h1:qklhhLq1aX+mtWk9cPHPzaBjWImj5ULL6C7HFJtXQMM=
 github.com/lightstep/lightstep-tracer-go v0.18.1/go.mod h1:jlF1pusYV4pidLvZ+XD0UBX0ZE6WURAspgAczcDHrL4=
@ -202,6 +207,7 @@ github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINE
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/profile v1.2.1/go.mod h1:hJw3o1OdXxsrSjjVksARp5W95eeEaEfptyVZyv6JUPA=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/posener/complete v1.1.1/go.mod h1:em0nMJCgc9GFtwrmVmEMR/ZL6WyhyjMBndrE9hABlRI=
 github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=
@ -255,6 +261,7 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20170815181823-89b8d40f7ca8/go.mod h1:ncp9v5uamzpCO7NfCPTXjqaC+bZgJeR0sMTm6dMHP7U=
 github.com/urfave/cli v1.20.0/go.mod h1:70zkFmudgCuE/ngEzBv17Jvp/497gISqfk5gWijbERA=
@ -379,9 +386,11 @@ google.golang.org/protobuf v1.20.1-0.20200309200217-e05f789c0967/go.mod h1:A+miE
 google.golang.org/protobuf v1.21.0/go.mod h1:47Nbq4nVaFHyn7ilMalzfO3qCViNmqZ2kzikPIcrTAo=
 google.golang.org/protobuf v1.23.0 h1:4MY060fB1DLGMB/7MBTLnwQUY6+F09GEiz6SsrNqyzM=
 google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6 h1:jMFz6MfLP0/4fUyZle81rXUoxOBFi19VUFKVDOQfozc=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/cheggaaa/pb.v1 v1.0.25/go.mod h1:V/YB90LKu/1FcN3WVnfiiE5oMCibMjukxqG/qStrOgw=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
@ -395,6 +404,7 @@ gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.5/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
 gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 honnef.co/go/tools v0.0.0-20180728063816-88497007e858/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=