$s = 'message-center-db: "http://message-center-db-1b.message-center-db.svc.cluster.local"';;

substr( $s, 0, index( $s, ':' ) ) =~ tr[-][_];;

print $s;;
message_center_db: "http://message-center-db-1b.message-center-db.svc.cluster.local"