Add playbook for prometheus alert tests

- Install prometheus snap
- Verify that the alert rules tests pass

Change-Id: I38883a431735546bae2033b6f34cc40644231a4c

playbooks/prometheus-alert-rules-test.yaml

@@ -0,0 +1,3 @@
+- hosts: all
+  roles:
+    - prometheus-alert-rules-test

roles/prometheus-alert-rules-test/tasks/main.yaml

@@ -0,0 +1,24 @@
+- name: snapd is installed
+  apt:
+    name: snapd
+  become: true
+
+- name: prometheus is installed
+  snap:
+    name: prometheus
+    channel: "{{ prometheus_channel | default('2/stable') }}"
+  become: true
+
+- name: Check if prometheus_alerts_test_rules_dir exists
+  stat:
+    path: "{{ zuul.project.src_dir }}/{{ prometheus_alerts_test_rules_dir }}"
+  register: prometheus_alerts_dir_exists
+
+- name: Exit if test rules dir doesn't exist
+  fail:
+    msg: "Directory {{ prometheus_alerts_test_rules_dir }} does not exist"
+  when: not prometheus_alerts_dir_exists.stat.exists
+
+- name: promtool tests pass
+  command:
+    cmd: bash -c 'promtool test rules {{ zuul.project.src_dir }}/{{ prometheus_alerts_test_rules_dir }}/*.yaml'

zuul.d/jobs.yaml

@@ -12,3 +12,8 @@
     requires: charm
     dependencies:
       - name: charmbuild
+
+- job:
+    name: prometheus-alert-rules-test
+    run: playbooks/prometheus-alert-rules-test.yaml
+    timeout: 600

zuul.d/project-templates.yaml

@@ -9,3 +9,13 @@
             nodeset: ubuntu-focal
         - zaza-smoke-test:
             nodeset: ubuntu-focal
+
+- project-template:
+    name: prometheus-alert-rules-test
+    description: |
+      This project template is defined to run prometheus alert rules
+      tests
+    check:
+      jobs:
+        - prometheus-alert-rules-test:
+            nodeset: ubuntu-focal