feat: initial installation role for prometheus

.gitignore

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+*.retry

README.md

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+# ansible-role-prometheus
+
+Installs Prometheus from GitHub releases on Linux. Architecture is auto-detected.
+The role is idempotent: it only downloads and extracts when the version changes.
+
+The service user and group must be created beforehand.
+Prometheus configuration (`prometheus.yml`) is out of scope for this role.
+
+## Requirements
+
+- Ansible >= 2.14
+
+## Role Variables
+
+| Variable | Default | Description |
+|---|---|---|
+| `prometheus_version` | `""` | Version to install (empty = latest) |
+| `prometheus_user` | `prometheus` | User to run Prometheus |
+| `prometheus_group` | `prometheus` | Group to run Prometheus |
+| `prometheus_install_dir` | `/opt/prometheus` | Binary and assets directory |
+| `prometheus_data_dir` | `/var/lib/prometheus` | TSDB storage directory |
+| `prometheus_config_dir` | `/etc/prometheus` | Configuration directory |
+| `prometheus_service_enabled` | `true` | Enable service at boot |
+| `prometheus_service_state` | `started` | Service state after installation |
+
+## Example Playbook
+
+```yaml
+- hosts: monitoring_servers
+  roles:
+    - role: ansible-role-prometheus
+      vars:
+        prometheus_user: prometheus
+        prometheus_group: prometheus
+```
+
+## License
+
+MIT

defaults/main.yml

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+---
+prometheus_version: ""
+prometheus_user: prometheus
+prometheus_group: prometheus
+prometheus_install_dir: /opt/prometheus
+prometheus_data_dir: /var/lib/prometheus
+prometheus_config_dir: /etc/prometheus
+prometheus_service_enabled: true
+prometheus_service_state: started

handlers/main.yml

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+---

meta/main.yml

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+---
+galaxy_info:
+  author: mathieu
+  description: Install Prometheus binary on Linux
+  license: MIT
+  min_ansible_version: "2.14"
+  platforms:
+    - name: Debian
+      versions: [bullseye, bookworm]
+    - name: Ubuntu
+      versions: [focal, jammy, noble]
+    - name: EL
+      versions: ["8", "9"]
+  galaxy_tags: [prometheus, monitoring, metrics]
+dependencies: []

tasks/main.yml

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+---
+- name: Set architecture fact
+  ansible.builtin.set_fact:
+    _prometheus_arch: "{{ {'x86_64': 'amd64', 'aarch64': 'arm64', 'armv7l': 'armv7'}.get(ansible_architecture, 'amd64') }}"
+
+- name: Get Prometheus release info from GitHub
+  ansible.builtin.uri:
+    url: >-
+      {{ 'https://api.github.com/repos/prometheus/prometheus/releases/latest'
+         if prometheus_version == ''
+         else 'https://api.github.com/repos/prometheus/prometheus/releases/tags/v' + prometheus_version }}
+    headers:
+      Accept: "application/vnd.github.v3+json"
+    return_content: true
+  register: _prometheus_release
+
+- name: Set version and download URL facts
+  ansible.builtin.set_fact:
+    _prometheus_version_tag: "{{ _prometheus_release.json.tag_name }}"
+    _prometheus_download_url: >-
+      {{ _prometheus_release.json.assets
+         | selectattr('name', 'search', 'linux-' + _prometheus_arch + '.tar.gz')
+         | map(attribute='browser_download_url')
+         | first }}
+
+- name: Read installed version
+  ansible.builtin.slurp:
+    src: "{{ prometheus_install_dir }}/.version"
+  register: _prometheus_installed_raw
+  ignore_errors: true
+  become: true
+
+- name: Set installed version fact
+  ansible.builtin.set_fact:
+    _prometheus_installed_version: >-
+      {{ (_prometheus_installed_raw.content | b64decode | trim)
+         if _prometheus_installed_raw is not failed else '' }}
+
+- name: Install or upgrade Prometheus
+  when: _prometheus_installed_version != _prometheus_version_tag
+  block:
+    - name: Download Prometheus archive
+      ansible.builtin.get_url:
+        url: "{{ _prometheus_download_url }}"
+        dest: /tmp/prometheus.tar.gz
+        mode: '0644'
+
+    - name: Create Prometheus installation directory
+      ansible.builtin.file:
+        path: "{{ prometheus_install_dir }}"
+        state: directory
+        owner: "{{ prometheus_user }}"
+        group: "{{ prometheus_group }}"
+        mode: '0755'
+      become: true
+
+    - name: Extract Prometheus archive
+      ansible.builtin.unarchive:
+        src: /tmp/prometheus.tar.gz
+        dest: "{{ prometheus_install_dir }}"
+        remote_src: true
+        extra_opts: [--strip-components=1]
+        owner: "{{ prometheus_user }}"
+        group: "{{ prometheus_group }}"
+      become: true
+
+    - name: Write installed version file
+      ansible.builtin.copy:
+        content: "{{ _prometheus_version_tag }}"
+        dest: "{{ prometheus_install_dir }}/.version"
+        owner: "{{ prometheus_user }}"
+        group: "{{ prometheus_group }}"
+        mode: '0644'
+      become: true
+
+    - name: Remove downloaded archive
+      ansible.builtin.file:
+        path: /tmp/prometheus.tar.gz
+        state: absent
+
+- name: Create Prometheus directories
+  ansible.builtin.file:
+    path: "{{ item }}"
+    state: directory
+    owner: "{{ prometheus_user }}"
+    group: "{{ prometheus_group }}"
+    mode: '0755'
+  become: true
+  loop:
+    - "{{ prometheus_data_dir }}"
+    - "{{ prometheus_config_dir }}"
+
+- name: Create Prometheus systemd service
+  ansible.builtin.copy:
+    content: |
+      [Unit]
+      Description=Prometheus
+      After=network-online.target
+      Wants=network-online.target
+
+      [Service]
+      Type=simple
+      User={{ prometheus_user }}
+      Group={{ prometheus_group }}
+      ExecStart={{ prometheus_install_dir }}/prometheus \
+        --config.file={{ prometheus_config_dir }}/prometheus.yml \
+        --storage.tsdb.path={{ prometheus_data_dir }} \
+        --web.console.templates={{ prometheus_install_dir }}/consoles \
+        --web.console.libraries={{ prometheus_install_dir }}/console_libraries
+      Restart=on-failure
+      RestartSec=5s
+
+      [Install]
+      WantedBy=multi-user.target
+    dest: /etc/systemd/system/prometheus.service
+    mode: '0644'
+  become: true
+
+- name: Enable and start Prometheus service
+  ansible.builtin.systemd:
+    name: prometheus
+    enabled: "{{ prometheus_service_enabled }}"
+    state: "{{ prometheus_service_state }}"
+    daemon_reload: true
+  become: true