2.7 Using Flipper

This is just a quick overview of what Flipper can do. More detail can be found elsewhere in this documentation. Help is available on the command line by running flipper --help for usage information and perldoc flipper for a brief overview.

Flipper's set command ensures an IP is running on a particular node. If it's already running on the node you specify, it won't be moved. If it's running on the other node, it will be moved.

The swap command moves IPs from one node to another. If you specify an IP, it will move only the IP you specify, otherwise all IPs will be moved to the other node.

The disable command moves any IPs that are up on a particular node to the other node. This is useful for taking a machine out of use for maintenance. The fail command is similar to the disable command, but is used for handling nodes which have suffered an external permanent or semi-permanent failure.

The following example demonstrates the use of the commands. We use the status command to display the current status:

$ flipper mike status
MASTERPAIR: mike
NODE: first_node has read IP, is read-only, replication running, 0s delay
NODE: second_node has write IP, is writable, replication running, 0s delay
$ flipper mike swap
$ flipper mike status
MASTERPAIR: mike
NODE: first_node has write IP, is writable, replication running, 0s delay
NODE: second_node has read IP, is read-only, replication running, 0s delay
$ flipper mike set read first_node
$ flipper mike status
MASTERPAIR: mike
NODE: first_node has read IP, has write IP, is writable, replication running, 0s delay
NODE: second_node is read-only, replication running, 0s delay
$ flipper mike disable first_node
$ flipper mike status
MASTERPAIR: mike
NODE: first_node is read-only, replication running, 0s delay
NODE: second_node has read IP, has write IP, is writable, replication running, 0s delay
$