install psycopg2 only once per db host

Signed-off-by: Anis FATHALLAH <anis@fathallah.fr>

Author: anisf

roles/deployment/databases/tasks/postgresql.yml

@@ -16,11 +16,11 @@
 
 - name: Ensure psycopg2 is installed
   package:
-    name: "{{ ((hostvars[databases[item].host]['ansible_os_family'] == 'RedHat') and (hostvars[databases[item].host]['ansible_distribution_major_version'] == '7')) | ternary('python-psycopg2', 'python3-psycopg2') }}"
-  with_items: "{{ databases }}"
-  delegate_to: "{{ databases[item].host }}"
+    name: "{{ ((hostvars[item]['ansible_os_family'] == 'RedHat') and (hostvars[item]['ansible_distribution_major_version'] == '7')) | ternary('python-psycopg2', 'python3-psycopg2') }}"
+  with_items: "{{ databases | json_query('*.host') | unique }}"
+  delegate_to: "{{ item }}"
   connection: ssh
-  when: databases[item].host in groups.db_server
+  when: item in groups.db_server
 
 - name: Create database roles
   postgresql_user: