test: add a molecule scenario covering three distribution families

The role was only linted statically so far, which is why every bug of the recent analysis passed the ci
unnoticed. The scenario converges the role in podman containers of Archlinux, Debian and Fedora, checks
idempotence and then verifies the result.

Verification covers the chain via openssl verify, the file modes of keys, certificates and directories,
the number of certificates in the fullchain of the client, its subject alternative names and the anchor in
the systems trust store. Root and intermediate use a passphrase so the protected code paths are exercised
as well.

Molecule ships only the default driver, so create and destroy are provided as playbooks. Three details
were needed to make it work. The connection has to be declared in the instance config, since molecule
ignores ansible_connection_options of the driver. Raw commands are passed through sh explicitly, because
the podman connection plugin splits them instead of using a shell. And the roles path has to point at the
parent of the project directory, which is the role itself.

Co-authored-by: Copilot <copilot@github.com>

molecule/default/converge.yml

@@ -0,0 +1,19 @@
+---
+
+- name: Converge
+  hosts: all
+  # Passphrases are fixtures, they exercise the protected code paths of the role.
+  vars:
+    certificate_authority_root_ca_common_name: "Molecule Root CA"
+    certificate_authority_root_ca_tls_key_passphrase: "molecule-root-ca"
+    certificate_authority_intermediate_ca_common_name: "Molecule Intermediate CA"
+    certificate_authority_intermediate_ca_tls_key_passphrase: "molecule-intermediate-ca"
+    certificate_authority_client_skip: false
+    certificate_authority_client_common_name: "molecule.example.local"
+    certificate_authority_client_subject_alternative_names:
+    - "DNS:molecule.example.local"
+    - "IP:10.11.12.13"
+  tasks:
+  - name: Include the role certificate_authority
+    ansible.builtin.include_role:
+      name: certificate_authority

molecule/default/create.yml

@@ -0,0 +1,25 @@
+---
+
+- name: Create
+  hosts: localhost
+  gather_facts: false
+  tasks:
+  - name: Start a container per platform
+    containers.podman.podman_container:
+      name: "{{ item.name }}"
+      image: "{{ item.image }}"
+      command: "sleep infinity"
+      state: started
+    loop: "{{ molecule_yml.platforms }}"
+    loop_control:
+      label: "{{ item.name }}"
+
+  - name: Write the instance config
+    ansible.builtin.copy:
+      content: |
+        {% for platform in molecule_yml.platforms %}
+        - instance: {{ platform.name }}
+          connection: containers.podman.podman
+        {% endfor %}
+      dest: "{{ molecule_instance_config }}"
+      mode: "0600"

molecule/default/destroy.yml

@@ -0,0 +1,19 @@
+---
+
+- name: Destroy
+  hosts: localhost
+  gather_facts: false
+  tasks:
+  - name: Remove the container of every platform
+    containers.podman.podman_container:
+      name: "{{ item.name }}"
+      state: absent
+    loop: "{{ molecule_yml.platforms }}"
+    loop_control:
+      label: "{{ item.name }}"
+
+  - name: Empty the instance config
+    ansible.builtin.copy:
+      content: "[]"
+      dest: "{{ molecule_instance_config }}"
+      mode: "0600"

molecule/default/molecule.yml

@@ -0,0 +1,24 @@
+---
+
+driver:
+  name: default
+  options:
+    managed: true
+    login_cmd_template: "podman exec --interactive --tty {instance} bash"
+
+platforms:
+- name: certificate-authority-archlinux
+  image: docker.io/library/archlinux:base
+- name: certificate-authority-debian
+  image: docker.io/library/debian:13
+- name: certificate-authority-fedora
+  image: registry.fedoraproject.org/fedora:43
+
+provisioner:
+  name: ansible
+  # The role under test is the project directory itself, so its parent has to be on the roles path.
+  env:
+    ANSIBLE_ROLES_PATH: "${MOLECULE_PROJECT_DIRECTORY}/.."
+  config_options:
+    defaults:
+      interpreter_python: auto_silent

molecule/default/prepare.yml

@@ -0,0 +1,22 @@
+---
+
+- name: Prepare
+  hosts: all
+  gather_facts: false
+  vars:
+    # The base images ship neither a python interpreter for ansible nor the tools the role shells out to.
+    _bootstrap: |
+      set -eu
+      if command -v pacman > /dev/null; then
+        pacman --sync --refresh --noconfirm ca-certificates gawk openssl python
+      elif command -v apt-get > /dev/null; then
+        apt-get update
+        apt-get install --yes ca-certificates gawk openssl python3
+      else
+        dnf install --assumeyes ca-certificates gawk openssl python3
+      fi
+  tasks:
+  # The podman connection plugin splits raw commands instead of passing them to a shell.
+  - name: Bootstrap the python interpreter and the tools required by the role
+    ansible.builtin.raw: "/bin/sh -c {{ _bootstrap | quote }}"
+    changed_when: true

molecule/default/verify.yml

@@ -0,0 +1,88 @@
+---
+
+- name: Verify
+  hosts: all
+  vars:
+    _root_ca_path: "/etc/ansible-playbook/pki/ca"
+    _intermediate_ca_path: "/etc/ansible-playbook/pki/intermediate"
+    _client_path: "/etc/ansible-playbook/pki/client"
+    # cert.pem and cert-req.pem are left out on purpose, the role does not pin their mode.
+    _expected_modes:
+      /etc/ansible-playbook/pki/ca: "0755"
+      /etc/ansible-playbook/pki/ca/privkey.pem: "0600"
+      /etc/ansible-playbook/pki/ca/all.pem: "0600"
+      /etc/ansible-playbook/pki/intermediate: "0755"
+      /etc/ansible-playbook/pki/intermediate/privkey.pem: "0600"
+      /etc/ansible-playbook/pki/intermediate/chain.pem: "0644"
+      /etc/ansible-playbook/pki/intermediate/fullchain.pem: "0644"
+      /etc/ansible-playbook/pki/intermediate/all.pem: "0600"
+      /etc/ansible-playbook/pki/client: "0755"
+      /etc/ansible-playbook/pki/client/privkey.pem: "0600"
+      /etc/ansible-playbook/pki/client/chain.pem: "0644"
+      /etc/ansible-playbook/pki/client/fullchain.pem: "0644"
+      /etc/ansible-playbook/pki/client/all.pem: "0600"
+    _trust_store_anchor:
+      Archlinux: "/etc/ca-certificates/trust-source/anchors/Molecule_Root_CA.pem"
+      Debian: "/usr/local/share/ca-certificates/Molecule_Root_CA.crt"
+      RedHat: "/etc/pki/ca-trust/source/anchors/Molecule_Root_CA.pem"
+  tasks:
+  - name: Stat the generated files
+    ansible.builtin.stat:
+      path: "{{ item.key }}"
+    register: _pki_files
+    loop: "{{ _expected_modes | dict2items }}"
+    loop_control:
+      label: "{{ item.key }}"
+
+  - name: Assert that the generated files exist with the expected mode
+    ansible.builtin.assert:
+      that:
+      - item.stat.exists
+      - item.stat.mode == item.item.value
+      fail_msg: "{{ item.item.key }} has mode {{ item.stat.mode | default('none') }} instead of {{ item.item.value }}"
+    loop: "{{ _pki_files.results }}"
+    loop_control:
+      label: "{{ item.item.key }}"
+
+  - name: Verify the client certificate against the root certificate authority
+    ansible.builtin.command:
+      cmd: >-
+        openssl verify
+        -CAfile {{ _root_ca_path }}/cert.pem
+        -untrusted {{ _intermediate_ca_path }}/cert.pem
+        {{ _client_path }}/cert.pem
+    changed_when: false
+
+  - name: Read the fullchain file of the client
+    ansible.builtin.slurp:
+      src: "{{ _client_path }}/fullchain.pem"
+    register: _client_fullchain
+
+  - name: Assert that the fullchain of the client holds the complete chain and ends with a newline
+    vars:
+      _content: "{{ _client_fullchain.content | b64decode }}"
+    ansible.builtin.assert:
+      that:
+      - _content | regex_findall('BEGIN CERTIFICATE') | length == 3
+      - _content.endswith('\n')
+      fail_msg: "unexpected content in {{ _client_path }}/fullchain.pem"
+
+  - name: Read the subject alternative names of the client certificate
+    community.crypto.x509_certificate_info:
+      path: "{{ _client_path }}/cert.pem"
+    register: _client_cert_info
+
+  - name: Assert that the requested subject alternative names are present
+    ansible.builtin.assert:
+      that: _client_cert_info.subject_alt_name | sort == ['DNS:molecule.example.local', 'IP:10.11.12.13']
+      fail_msg: "unexpected subject alternative names {{ _client_cert_info.subject_alt_name }}"
+
+  - name: Stat the anchor in the systems trust store
+    ansible.builtin.stat:
+      path: "{{ _trust_store_anchor[ansible_facts['os_family']] }}"
+    register: _anchor
+
+  - name: Assert that the root certificate authority was imported into the systems trust store
+    ansible.builtin.assert:
+      that: _anchor.stat.exists
+      fail_msg: "{{ _trust_store_anchor[ansible_facts['os_family']] }} is missing"