Check nested struct initialization during CM upgrade

During the upgrade of an existing pgcluster, the existing
<clustername>-pgha-config configmap is used to populate
the struct object so that key values are upgraded, as needed.

In certain cases where the configmap exists but was is not
initialized as expected, the exist function can hit a runtime
panic when referencing uninitialized structs or maps.

This update checks that these structs and maps are not nil
before attempting to set any values.

Author: tjmoore4

internal/operator/cluster/upgrade.go

@@ -879,16 +879,24 @@ func updateClusterConfig(clientset kubeapi.Interface, pgcluster *crv1.Pgcluster,
 		return err
 	}
 
-	// set the updated path values for both DCS and LocalDB configs
+	// set the updated path values for both DCS and LocalDB configs, if the fields and maps exist
 	// as of version 4.6, the /crunchyadm directory no longer exists (previously set as a unix socket directory)
 	// and the /opt/cpm... directories are now set under /opt/crunchy
-	dcsConf.PostgreSQL.Parameters["unix_socket_directories"] = "/tmp"
-	dcsConf.PostgreSQL.Parameters["archive_command"] = `source /opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-set-env.sh && pgbackrest archive-push "%p"`
-	dcsConf.PostgreSQL.RecoveryConf["restore_command"] = `source /opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-set-env.sh && pgbackrest archive-get %f "%p"`
+	if dcsConf.PostgreSQL != nil && dcsConf.PostgreSQL.Parameters != nil {
+		dcsConf.PostgreSQL.Parameters["unix_socket_directories"] = "/tmp"
+		dcsConf.PostgreSQL.Parameters["archive_command"] = `source /opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-set-env.sh && pgbackrest archive-push "%p"`
+		dcsConf.PostgreSQL.RecoveryConf["restore_command"] = `source /opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-set-env.sh && pgbackrest archive-get %f "%p"`
+	}
 
-	localDBConf.PostgreSQL.Callbacks.OnRoleChange = "/opt/crunchy/bin/postgres-ha/callbacks/pgha-on-role-change.sh"
-	localDBConf.PostgreSQL.PGBackRest.Command = "/opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-create-replica.sh replica"
-	localDBConf.PostgreSQL.PGBackRestStandby.Command = "/opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-create-replica.sh standby"
+	if localDBConf.PostgreSQL.Callbacks != nil {
+		localDBConf.PostgreSQL.Callbacks.OnRoleChange = "/opt/crunchy/bin/postgres-ha/callbacks/pgha-on-role-change.sh"
+	}
+	if localDBConf.PostgreSQL.PGBackRest != nil {
+		localDBConf.PostgreSQL.PGBackRest.Command = "/opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-create-replica.sh replica"
+	}
+	if localDBConf.PostgreSQL.PGBackRestStandby != nil {
+		localDBConf.PostgreSQL.PGBackRestStandby.Command = "/opt/crunchy/bin/postgres-ha/pgbackrest/pgbackrest-create-replica.sh standby"
+	}
 
 	// set up content and patch DCS config
 	dcsContent, err := yaml.Marshal(dcsConf)