[RFE] pre and post failover actions

[Peter Matulis]

The failover to a secondary site for Cinder volume replication (volumes backed by two Ceph clusters) takes too long (and can even fail) due to default Cinder configuration affecting timeouts and retries.

In the situation where one site (cluster) is known to be down I don't see why a deliberate choice should be subject to long timeouts/retries.

The workaround is to manually change the defaults pre-failover and then revert them post-failover:

$ juju ssh cinder-ceph-a/0
> sudo apt install -y crudini
> sudo crudini --set /etc/cinder/cinder.conf cinder-ceph-a rados_connect_timeout 1
> sudo crudini --set /etc/cinder/cinder.conf cinder-ceph-a rados_connection_retries 1
> sudo crudini --set /etc/cinder/cinder.conf cinder-ceph-a rados_connection_interval 0
> sudo crudini --set /etc/cinder/cinder.conf cinder-ceph-a replication_connect_timeout 1
> sudo systemctl restart cinder-volume
> exit

$ cinder failover-host cinder@cinder-ceph-a

$ juju ssh cinder-ceph-a/0
> sudo crudini --del /etc/cinder/cinder.conf cinder-ceph-a rados_connect_timeout
> sudo crudini --del /etc/cinder/cinder.conf cinder-ceph-a rados_connection_retries
> sudo crudini --del /etc/cinder/cinder.conf cinder-ceph-a rados_connection_interval
> sudo crudini --del /etc/cinder/cinder.conf cinder-ceph-a replication_connect_timeout
> sudo systemctl restart cinder-volume
> exit

Is it possible to have actions for this?:

$ juju run-action --wait cinder-ceph-a pre-failover
$ cinder failover-host cinder@cinder-ceph-a
$ juju run-action --wait cinder-ceph-a post-failover

An alternative would be to implement a --force option in the cinder API client.

[Alex Kavanagh (ajkavanagh)]

Triage; looks like an interesting addition.