Merge pull request #1 from JensTimmerman/patch-1

only add new databases if they are not yet present

tasks/databases.yml

@@ -1,4 +1,16 @@
 ---
+- name: Collect PostgreSQL db_names
+  postgresql_query:
+    login_host: "{{ item.login_host | default('localhost') }}"
+    login_password: "{{ item.login_password | default(omit) }}"
+    login_user: "{{ item.login_user | default(postgresql_user) }}"
+    login_unix_socket: "{{ item.login_unix_socket | default(postgresql_unix_socket_directories[0]) }}"
+    port: "{{ item.port | default(omit) }}"
+    query: "SELECT datname FROM pg_database;"
+  register: postgresql_present_db_names
+  become: true
+  become_user: "{{ postgresql_user }}"
+  
 - name: Ensure PostgreSQL databases are present.
   postgresql_db:
     name: "{{ item.name }}"
@@ -19,3 +31,5 @@
   # See: https://github.com/ansible/ansible/issues/16048#issuecomment-229012509
   vars:
     ansible_ssh_pipelining: true
+  when: "item.name not in (postgresql_present_db_names.query_result | map(attribute='datname') )"
+