Update prometheus role for ansible-lint, argument specs, and README (#208)

Signed-off-by: Webster Mudge <wmudge@cloudera.com>

Author: wmudge

roles/prometheus/README.md

@@ -1,17 +1,69 @@
-<!--
- Copyright 2024 Cloudera, Inc.
+# prometheus
 
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
+Install Prometheus.
 
-     https://www.apache.org/licenses/LICENSE-2.0
+This role automates the installation of the Prometheus monitoring system from its official distribution archive. It sets up the necessary directories for configuration and the time-series database (TSDB), creates a dedicated system user and group for the service, and installs a basic Prometheus configuration to get started.
 
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
--->
+The role will:
+- Create a dedicated system user and group (`prometheus`).
+- Create necessary directories for Prometheus configuration (`/etc/prometheus`) and TSDB storage (`/var/lib/prometheus`).
+- Download the Prometheus distribution tarball.
+- Extract the Prometheus binary and related files to the installation directory.
+- Install a basic `prometheus.yml` configuration file.
+- Set up a `systemd` service for Prometheus.
+- Enable and start the Prometheus service, ensuring it runs on system boot.
 
-# prometheus
+# Requirements
+
+- Target host must have `systemd` for service management.
+- Internet access on the target host to download the Prometheus tarball.
+
+# Dependencies
+
+None.
+
+# Parameters
+
+| Variable | Type | Required | Default | Description |
+| --- | --- | --- | --- | --- |
+| `prometheus_tarball_url` | `str` | `False` | `https://github.com/prometheus/prometheus/releases/download/v2.48.1/prometheus-2.48.1.linux-amd64.tar.gz` | URL to the Prometheus distribution archive file. |
+| `prometheus_directory` | `path` | `False` | `/etc/prometheus` | Prometheus configuration directory. |
+| `prometheus_tsdb_directory` | `path` | `False` | `/var/lib/prometheus` | Prometheus TSDB directory. |
+| `prometheus_tarball_file` | `str` | `False` | `prometheus.tar.gz` | Intermediate archive file name for the downloaded tarball. |
+| `prometheus_user` | `str` | `False` | `prometheus` | Prometheus service user. |
+| `prometheus_group` | `str` | `False` | `prometheus` | Prometheus service group. |
+| `prometheus_service_directory` | `path` | `False` | `/etc/systemd/system/prometheus.service` | Prometheus Systemd service directory (full path to the service file). |
+
+# Example Playbook
+
+```yaml
+- hosts: monitoring_servers
+  tasks:
+    - name: Install Prometheus server with custom settings
+      ansible.builtin.import_role:
+        name: prometheus
+      vars:
+        prometheus_tarball_url: "[https://github.com/prometheus/prometheus/releases/download/v2.49.0/prometheus-2.49.0.linux-amd64.tar.gz](https://github.com/prometheus/prometheus/releases/download/v2.49.0/prometheus-2.49.0.linux-amd64.tar.gz)"
+        prometheus_directory: "/opt/prometheus/config"
+        prometheus_tsdb_directory: "/data/prometheus_tsdb"
+        prometheus_user: "prom_admin"
+        prometheus_group: "prom_admin"
+```
+
+# License
+
+```
+Copyright 2025 Cloudera, Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+  https://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+```

roles/prometheus/defaults/main.yml

@@ -1,6 +1,4 @@
----
-
-# Copyright 2024 Cloudera, Inc. All Rights Reserved.
+# Copyright 2025 Cloudera, Inc. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -14,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+---
+
 prometheus_tarball_url: https://github.com/prometheus/prometheus/releases/download/v2.48.1/prometheus-2.48.1.linux-amd64.tar.gz
 prometheus_directory: /etc/prometheus
 prometheus_tsdb_directory: /var/lib/prometheus

roles/prometheus/handlers/main.yml

@@ -1,5 +1,4 @@
----
-# Copyright 2024 Cloudera, Inc. All Rights Reserved.
+# Copyright 2025 Cloudera, Inc. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -13,7 +12,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-- name: Restart prometheus
+---
+
+- name: Enable Prometheus
+  block:
+    - name: Reload systemd daemon
+      ansible.builtin.systemd:
+        daemon_reload: true
+
+    - name: Enable and start Prometheus service
+      ansible.builtin.systemd:
+        name: prometheus
+        state: started
+        enabled: true
+
+- name: Restart Prometheus
   ansible.builtin.service:
     name: prometheus
     state: restarted

roles/prometheus/meta/argument_specs.yml

@@ -0,0 +1,59 @@
+# Copyright 2025 Cloudera, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+argument_specs:
+  main:
+    short_description: Install Prometheus.
+    description:
+      - Install Prometheus from the distribution archive file.
+      - Set up the local time-series database.
+      - Set up the service user and group.
+      - Install a basic configuration.
+    author: Cloudera Labs
+    options:
+      prometheus_tarball_url:
+        description: URL to the Prometheus distribution archive file.
+        type: str
+        required: false
+        default: https://github.com/prometheus/prometheus/releases/download/v2.48.1/prometheus-2.48.1.linux-amd64.tar.gz
+      prometheus_directory:
+        description: Prometheus configuration directory.
+        type: path
+        required: false
+        default: /etc/prometheus
+      prometheus_tsdb_directory:
+        description: Prometheus TSDB directory.
+        type: path
+        required: false
+        default: /var/lib/prometheus
+      prometheus_tarball_file:
+        description: Intermediate archive file name.
+        type: str
+        required: false
+        default: prometheus.tar.gz
+      prometheus_user:
+        description: Prometheus service user.
+        type: str
+        required: false
+        default: prometheus
+      prometheus_group:
+        description: Prometheus service group.
+        type: str
+        required: false
+        default: prometheus
+      prometheus_service_directory:
+        description: Prometheus Systemd service directory.
+        type: path
+        required: false
+        default: /etc/systemd/system/prometheus.service

roles/prometheus/tasks/main.yml

@@ -1,5 +1,4 @@
----
-# Copyright 2024 Cloudera, Inc. All Rights Reserved.
+# Copyright 2025 Cloudera, Inc. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -13,9 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+---
+
 - name: Create Prometheus directory
   ansible.builtin.file:
     path: "{{ prometheus_directory }}"
+    mode: "0755"
     state: directory
 
 - name: Create a temporary directory
@@ -27,15 +29,16 @@
   ansible.builtin.get_url:
     url: "{{ prometheus_tarball_url }}"
     dest: "{{ __prometheus_tmp.path }}/{{ prometheus_tarball_file }}"
+    mode: "0755"
 
-- name: Extract tarball
+- name: Extract Prometheus tarball
   ansible.builtin.unarchive:
     src: "{{ __prometheus_tmp.path }}/{{ prometheus_tarball_file }}"
     dest: "{{ prometheus_directory }}"
     extra_opts: --strip-components=1
     remote_src: true
 
-- name: Remove the temporary  directory
+- name: Remove the temporary directory
   when: __prometheus_tmp is defined
   ansible.builtin.file:
     path: "{{ __prometheus_tmp.path }}"
@@ -54,34 +57,24 @@
     state: directory
     recurse: true
 
-- name: Set ownership of all files inside  /etc/prometheus
+- name: Set ownership of Prometheus files
   ansible.builtin.file:
     path: "{{ prometheus_directory }}"
     owner: "{{ prometheus_user }}"
     group: "{{ prometheus_group }}"
+    mode: "0755"
     recurse: true
 
 - name: Create Prometheus service template
   ansible.builtin.template:
     src: prometheus.service.j2
     dest: "{{ prometheus_service_directory }}"
-  register: __prometheus_service
-
-- name: Start and enable prometheus service
-  when: __prometheus_service.changed
-  block:
-    - name: Reload systemd daemon
-      ansible.builtin.systemd:
-        daemon_reload: true
-
-    - name: Enable and start prometheus service
-      ansible.builtin.systemd:
-        name: prometheus
-        state: started
-        enabled: true
+    mode: "0755"
+  notify: Enable Prometheus
 
 - name: Update Prometheus configuration
   ansible.builtin.template:
     src: prometheus.yml.j2
     dest: /etc/prometheus/prometheus.yml
-  notify: restart prometheus
+    mode: "0755"
+  notify: Restart Prometheus