service: Support postgres >= 18 and postgres upgrades

roles/service/defaults/main.yaml

@@ -22,7 +22,8 @@ service_database_type: none
 service_database_additional_networks: []
 service_database_secret_type: mount
 service_database_secret_target: "{{ service_database_type }}"
-service_postgres_image: docker.io/library/postgres
+service_postgres_image: docker.io/pgautoupgrade/pgautoupgrade
+service_postgres_tag: alpine
 service_redis: false
 
 service_additional_containers: []

roles/service/meta/argument_specs.yaml

@@ -294,7 +294,7 @@ argument_specs:
         description:
           - Postgresql version to use.
           - Can be debian (n) or alpine-based (n-alpine), where n can be major version like 14 or minor like 14.13.
-          - Required if service_database_type is postgres, does nothing otherwise
+          - Ignored if database type is not postgres.
           - If a custom postgres image is specified, see that image documentation for supported tags.
         type: str
         required: false

roles/service/vars/database/postgres.yaml

@@ -1,6 +1,12 @@
 ---
 _service_database_image: "{{ service_postgres_image }}:{{ service_postgres_tag }}"
-_service_database_mount_destination: /var/lib/postgresql/data
+_service_database_mount_destination: >-
+  {{
+    '/var/lib/postgresql/data'
+    if (service_postgres_tag | split('-') | length > 1)
+      and (service_postgres_tag | split('-') | first) is version('18', '<')
+    else '/var/lib/postgresql'
+  }}
 _service_database_env:
   POSTGRES_USER: "{{ service_name | replace('-', '_') }}"
   POSTGRES_PASSWORD_FILE: "/run/secrets/{{ service_database_type }}"