added option to set how long data is stored

defaults/main.yml

@@ -4,3 +4,4 @@ fqdn: "{{inventory_hostname}}"
 domain_name: "{{fqdn|replace((ansible_hostname + '.'),'')}}"
 alertmanagers: "{{groups['alertmanager']}}"
 blackbox_exporters: "{{groups['blackbox_exporter']}}"
+prometheus_tsdb_retention_time: 15d

tasks/debian.yml

@@ -10,3 +10,4 @@
     dest: /etc/default/prometheus
     src: default_prometheus.j2
   notify: restart prometheus
+  tags: prometheus_conf

tasks/main.yml

@@ -3,6 +3,7 @@
 - import_tasks: all.yml
 
 - include_tasks: "{{ansible_os_family|lower}}.yml"
+  tags: prometheus_conf
 
 - name: client certificates
   import_role:

templates/default_prometheus.j2

 # Set the command-line arguments to pass to the server.
-ARGS='--web.listen-address="[::1]:9090"'
+ARGS='--web.listen-address="[::1]:9090" --storage.tsdb.retention.time="{{prometheus_tsdb_retention_time}}"'
 
 # Prometheus supports the following options:
 #  --config.file="/etc/prometheus/prometheus.yml"