Module cartridge.failover
Gather information regarding instances leadership.
Failover can operate in two modes:
- In
disabled
mode the leader is the first server configured intopology.replicasets[].master
array. - In
eventual
mode the leader isn’t elected consistently. Instead, every instance in cluster thinks the leader is the first healthy server in replicaset, while instance health is determined according to membership status (the SWIM protocol). - In
stateful
mode leaders appointments are polled from the external storage. (Added in v2.0.2-2)
This module behavior depends on the instance state.
From the very beginning it reports is_rw() == false
,
is_leader() == false
, get_active_leaders() == {}
.
The module is configured when the instance enters ConfiguringRoles
state for the first time. From that moment it reports actual values
according to the mode set in clusterwide config.
(Added in v1.2.0-17)
Generate appointments according to clusterwide configuration. Used in ‘disabled’ failover mode.
Generate appointments according to membership status. Used in ‘eventual’ failover mode.
Get appointments from external storage. Used in ‘stateful’ failover mode.
Accept new appointments.
Get appointments wherever they come from and put them into cache. Cached active_leaders table is never modified, but overriden by it’s modified copy (if necessary).
Parameters:
- replicaset_uuid: ({[string]=string}) to leader_uuid map
Returns:
(boolean) Whether leadership map has changed
Perform the fencing healthcheck.
Fencing is actuated when the instance disconnects from both the state provider and a replica, i.e. the check returns false.
Returns:
(boolean) true / false
Check if current instance has persisted his vclock.
Returns:
(boolean) true / false
Check if failover suppressed on current instance.
Returns:
(boolean) true / false
Check if current configuration implies consistent switchover.
Returns:
(boolean) true / false
Force inconsistent leader switching. Do it by resetting vclockkeepers in state provider.
Parameters:
- replicaset_uuid: ({[string]=string,…}) to leader_uuid mapping
Returns:
(boolean) true
Or
(nil)
(table) Error description
Wait when promoted instances become vclockkeepers.
Parameters:
- replicaset_uuid: ({[string]=string,…}) to leader_uuid mapping
Returns:
(boolean) true
Or
(nil)
(table) Error description
Set internal failover options.
Available options are: WAITLSN_PAUSE, WAITLSN_TIMEOUT, LONGPOLL_TIMEOUT, NETBOX_CALL_TIMEOUT
Returns:
(boolean) true
Or
(nil)
(table) Error description