prometheus: add customizable storage retention, default to 10 years

roles/prometheus/defaults/main.yml

@@ -2,5 +2,6 @@
 
 prometheus_scrape_interval: 5s
 prometheus_evaluation_interval: 15s
+prometheus_storage_retention: 3650d
 prometheus_install_grafana: false
 prometheus_hcloud_relabel_configs: []

roles/prometheus/meta/argument_specs.yml

@@ -14,6 +14,11 @@ argument_specs:
         type: str
         required: false
         default: 15s
+      prometheus_storage_retention:
+        description: Period of time for which prometheus metrics are stored for. A number followed by unit (s, m, h, d, w, y)
+        type: str
+        required: false
+        default: 3650d
       prometheus_hcloud_token:
         description: Access token for hetzner cloud service discovery. It will be enabled if this variable is defined
         type: str

roles/prometheus/tasks/main.yml

@@ -7,6 +7,13 @@
     docker_service: prometheus
     docker_image: prom/prometheus
     reverse_proxy_type: none
+    docker_command:
+      - "--config.file=/etc/prometheus/prometheus.yml"
+      - "--storage.tsdb.path=/prometheus"
+      - "--storage.tsdb.retention={{ prometheus_storage_retention }}"
+      - "--web.console.libraries=/usr/share/prometheus/console_libraries"
+      - "--web.console.templates=/usr/share/prometheus/consoles"
+
     docker_volumes:
       - name: data
         path: /prometheus