postgresql: Fix postgresql@.service customization

postgresql/files/postgresql.service.override.conf

@@ -0,0 +1,5 @@
+[Service]
+OOMScoreAdjust=-1000
+Environment=PG_OOM_ADJUST_FILE=/proc/self/oom_score_adj
+Environment=PG_MASTER_OOM_SCORE_ADJ=-1000
+Environment=PG_CHILD_OOM_SCORE_ADJ=0

postgresql/tasks/config.yml

@@ -1,8 +1,14 @@
 ---
+- name: Ensure /etc/systemd/system/postgresql.service.d exists
+  file:
+    path: /etc/systemd/system/postgresql@.service.d
+    state: directory
+    recurse: true
+
 - name: Override PostgreSQL systemd unit
-  template:
-    src: postgresql.service.j2
-    dest: /etc/systemd/system/multi-user.target.wants/postgresql.service
+  copy:
+    src: postgresql.service.override.conf
+    dest: /etc/systemd/system/postgresql@.service.d/override.conf
     force: yes
   notify:
     - reload systemd

postgresql/templates/postgresql.service.j2

@@ -1,19 +0,0 @@
-# systemd service for managing all PostgreSQL clusters on the system. This
-# service is actually a systemd target, but we are using a service since
-# targets cannot be reloaded.
-
-[Unit]
-Description=PostgreSQL RDBMS
-
-[Service]
-OOMScoreAdjust=-1000
-Environment=PG_OOM_ADJUST_FILE=/proc/self/oom_score_adj
-Environment=PG_MASTER_OOM_SCORE_ADJ=-1000
-Environment=PG_CHILD_OOM_SCORE_ADJ=0
-Type=oneshot
-ExecStart=/bin/true
-ExecReload=/bin/true
-RemainAfterExit=on
-
-[Install]
-WantedBy=multi-user.target