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Configuring Cartridge failover

Configuring Cartridge failover

The cartridge failover command lets you configure Cartridge failover.

cartridge failover [subcommand] [flags] [args]

--name Application name.
--file Path to the file containing failover settings. Defaults to failover.yml.

failover also supports global flags.

Failover is configured through the Cartridge Lua API.

To run the failover, cartridge-cli connects to a random configured instance, so you must have a topology configured. To learn more, see the cartridge replicasets command. You might also want to check out the documentation on Cartridge failover architecture.

You can manage failover in the following ways:

cartridge failover set [mode] [flags]

This command lets you set a failover mode. Learn more about Cartridge failover modes.

  • stateful
  • eventual
  • disabled

--state-provider Failover state provider. Can be stateboard or etcd2. Used only in the stateful mode.
--params Failover parameters. Described in a JSON-formatted string like "{'fencing_timeout': 10', 'fencing_enabled': true}".
--provider-params Failover provider parameters. Described in a JSON-formatted string like "{'lock_delay': 14}".

To learn more about the parameters, check the corresponding section of this document.

Unlike in the case with setup, don’t pass unnecessary parameters. For example, don’t specify the --state-provider flag when the mode is eventual, otherwise you will get an error.

cartridge failover setup --file [configuration file]

The failover configuration file defaults to failover.yml. See the full description of parameters to include in the failover configuration.

mode: stateful
state_provider: stateboard
stateboard_params:
    uri: localhost:4401
    password: passwd
failover_timeout: 15

You can leave extra parameters in the file, which may be convenient. Suppose you have stateful etcd2 failover configured and want to change it to stateful stateboard. You don’t have to delete etcd2_params from the file, but you can just add stateboard_params and change the state_provider. Then you might want to switch the failover to the eventual mode. This doesn’t require removing etcd2_params or stateboard_params from the configuration file either.

However, be careful: all the parameters described in the configuration file will be applied on the Cartridge side. Thus, etcd2_params and stateboard_params from the example above will still be applied in the eventual mode, although they are intended for use with the stateful mode.

cartridge failover status [flags]

Checks failover status.

cartridge failover disable [flags]

Disables failover. Another way to disable failover is to specify the disabled mode with set or in the configuration file (see above).

mode (Required) Failover mode. Possible values: disabled, eventual, stateful.
failover_timeout Timeout in seconds used by membership to mark suspect members as dead.
fencing_enabled Abandon leadership when both the state provider quorum and at least one replica are lost. Works for stateful mode only.
fencing_timeout Time in seconds to actuate fencing after the check fails.
fencing_pause Period in seconds to perform the check.

Other parameters are mode-specific.

If the eventual mode is specified, no additional parameters are required.

Read the documentation to learn more about eventual failover.

stateful failover requires the following parameters:

state_provider External state provider type. Supported providers: stateboard, etcd2.
stateboard_params

Stateboard configuration:

  • uri (required): Stateboard instance URI.
  • password (required): Stateboard instance password.
etcd2_params

Configuration for etcd2:

  • prefix: Prefix for etcd keys (<prefix>/lock and <prefix>/leaders).
  • lock_delay: Timeout in seconds. Defines the lock’s time-to-live. Default value in Cartridge is 10.
  • endpoints: URIs used to discover and access etcd cluster instances. Default value in Cartridge is ['http://localhost:2379', 'http://localhost:4001'].
  • username
  • password

Read the documentation to learn more about stateful failover.