0e971a37aa
* ignore_unreachable for etcd dir cleanup ignore_errors ignores errors occur within "file" module. However, when the target node is offline, the playbook will still fail at this task with node "unreachable" state. Setting "ignore_unreachable: true" allows the playbook to bypass offline nodes and move on to proceed recovery tasks on remaining online nodes. * Re-arrange control plane recovery runbook steps * Remove suggestion to manually update IP addresses The suggestion was added in48a182844c4 years ago. But a new task added 2 years ago, inee0f1e9d58, automatically update API server arg with updated etcd node ip addresses. This suggestion is no longer needed.
2.0 KiB
Recovering the control plane
To recover from broken nodes in the control plane use the "recover-control-plane.yml" playbook.
Examples of what broken means in this context:
- One or more bare metal node(s) suffer from unrecoverable hardware failure
- One or more node(s) fail during patching or upgrading
- Etcd database corruption
- Other node related failures leaving your control plane degraded or nonfunctional
Note that you need at least one functional node to be able to recover using this method.
Runbook
- Backup what you can
- Provision new nodes to replace the broken ones
- Move any broken etcd nodes into the "broken_etcd" group, make sure the "etcd_member_name" variable is set.
- Move any broken control plane nodes into the "broken_kube_control_plane" group.
- Place the surviving nodes of the control plane first in the "etcd" and "kube_control_plane" groups
- Add the new nodes below the surviving control plane nodes in the "etcd" and "kube_control_plane" groups
Then run the playbook with --limit etcd,kube_control_plane and increase the number of ETCD retries by setting -e etcd_retries=10 or something even larger. The amount of retries required is difficult to predict.
When finished you should have a fully working control plane again.
Recover from lost quorum
The playbook attempts to figure out it the etcd quorum is intact. If quorum is lost it will attempt to take a snapshot from the first node in the "etcd" group and restore from that. If you would like to restore from an alternate snapshot set the path to that snapshot in the "etcd_snapshot" variable.
-e etcd_snapshot=/tmp/etcd_snapshot
Caveats
- The playbook has only been tested with fairly small etcd databases.
- There may be disruptions while running the playbook.
- There are absolutely no guarantees.
If possible try to break a cluster in the same way that your target cluster is broken and test to recover that before trying on the real target cluster.