Handle retry connect to Postgres when ping return EOF error. (zalando#2339)

* Handle retry connect to Postgres when ping return EOF error.
* Update pkg/cluster/database.go

Co-authored-by: Felix Kunde <[email protected]>

---------

Co-authored-by: Trung Minh Lai <[email protected]>
Co-authored-by: Felix Kunde <[email protected]>

Author: 3 people

pkg/cluster/database.go

@@ -154,7 +154,9 @@ func (c *Cluster) initDbConnWithName(dbname string) error {
 				return false, err2
 			}
 
-			return false, err
+			// Retry open connection until succeeded.
+			c.logger.Warningf("could not connect to Postgres database: %v", err)
+			return false, nil
 		})
 
 	if finalerr != nil {