Add PostgreSQL dir with socket to Docker container as a volume

Also explicitly set path to pg_dump 9.6 to avoid using old 9.5 postgres
client.

Fixes: PROD-31827

Change-Id: I727073c1caec40f11b87afcd64e31cdc50185a83
(cherry-picked from commit a1b31b7f2f39cfcd0ee2856a10a96f35d4c5e80c)
diff --git a/backupninja/client/single.yml b/backupninja/client/single.yml
index 0ea839b..3d6d0a9 100644
--- a/backupninja/client/single.yml
+++ b/backupninja/client/single.yml
@@ -3,6 +3,8 @@
 parameters:
   backupninja:
     client:
+      extra_params:
+        PGSQLDUMP: /usr/lib/postgresql/${_param:postgresql_major_version}/bin/pg_dump
       scheduling:
         when:
           - manual
diff --git a/defaults/init.yml b/defaults/init.yml
index 12ced59..b7995d8 100644
--- a/defaults/init.yml
+++ b/defaults/init.yml
@@ -13,6 +13,7 @@
 - system.defaults.glusterfs
 - system.defaults.nginx
 - system.defaults.jenkins
+- system.defaults.postgresql
 - system.defaults.maas
 - system.defaults.opencontrail
 - system.defaults.openstack
diff --git a/defaults/postgresql/init.yml b/defaults/postgresql/init.yml
new file mode 100644
index 0000000..7ee5704
--- /dev/null
+++ b/defaults/postgresql/init.yml
@@ -0,0 +1,4 @@
+parameters:
+  _param:
+    postgresql_major_version: '9.6'
+
diff --git a/docker/swarm/stack/postgresql.yml b/docker/swarm/stack/postgresql.yml
index 12eb874..2d6d7e7 100644
--- a/docker/swarm/stack/postgresql.yml
+++ b/docker/swarm/stack/postgresql.yml
@@ -26,5 +26,6 @@
                   condition: any
               volumes:
                 - /srv/volumes/postgresql/data:/var/lib/postgresql/data
+                - /var/run/postgresql:/var/run/postgresql
               ports:
                 - ${_param:postgresql_exposed_port}:${_param:postgresql_bind_port}