As of v0.1.7, you can configure a RKE cluster to automatically take snapshots of etcd. In a disaster scenario, you can restore these snapshots, which are stored on other nodes in the cluster.
One-Time Snapshots
RKE can take a one-time snapshot of a running etcd node in a RKE cluster. The snapshot is automatically saved in /opt/rke/etcd-snapshots.
$ rke etcd snapshot-save --config cluster.yml
WARN[0000] Name of the snapshot is not specified using [rke_etcd_snapshot_2018-05-17T23:32:08+02:00]
INFO[0000] Starting saving snapshot on etcd hosts
INFO[0000] [dialer] Setup tunnel for host [x.x.x.x]
INFO[0001] [dialer] Setup tunnel for host [y.y.y.y]
INFO[0002] [dialer] Setup tunnel for host [z.z.z.z]
INFO[0003] [etcd] Saving snapshot [rke_etcd_snapshot_2018-05-17T23:32:08+02:00] on host [x.x.x.x]
INFO[0004] [etcd] Successfully started [etcd-snapshot-once] container on host [x.x.x.x]
INFO[0004] [etcd] Saving snapshot [rke_etcd_snapshot_2018-05-17T23:32:08+02:00] on host [y.y.y.y]
INFO[0005] [etcd] Successfully started [etcd-snapshot-once] container on host [y.y.y.y]
INFO[0005] [etcd] Saving snapshot [rke_etcd_snapshot_2018-05-17T23:32:08+02:00] on host [z.z.z.z]
INFO[0006] [etcd] Successfully started [etcd-snapshot-once] container on host [z.z.z.z]
INFO[0006] Finished saving snapshot [rke_etcd_snapshot_2018-05-17T23:32:08+02:00] on all etcd hosts
The command will save a snapshot of etcd from each etcd node in the cluster config file and will save it in /opt/rke/etcd-snapshots. When running the command, an additional container is created to take the snapshot. When the snapshot is completed, the container is automatically removed.
Etcd Recurring Snapshots
To schedule a recurring automatic etcd snapshot save, you can enable the etcd-snapshot service. etcd-snapshot runs in a service container alongside the etcd container. etcd-snapshot automatically takes a snapshot of etcd and stores them to its local disk in /opt/rke/etcd-snapshots.
In the cluster.yml, you need to turn enable snapshot as part of the etcd service. Additionally, you want to specify creation and retention for the snapshot service.
When a cluster is launched with the etcd snapshot service enabled, you can view the etcd-snapshot logs to confirm backups are being created automatically.
$ docker logs etcd-snapshot
time="2018-05-04T18:39:16Z" level=info msg="Initializing Rolling Backups" creation=1m0s retention=24h0m0s
For every node that has the etcd role, these backups are saved to /opt/rke/etcd-snapshots/.
Snapshot Options Snapshot
By default, the recurring snapshot service is disabled. To enable the service, you need to define it as part of etcd and set it to true. Creation
By default, the snapshot service will take snapshots every 5 minutes (5m0s). You can change the time between snapshots as part of the creation directive for the etcd service. Retention
By default, all snapshots are saved for 24 hours (24h) before being deleted and purged. You can change how long to store a snapshot as part of the retention directive for the etcd service.
Etcd Disaster recovery
If there is a disaster with your Kubernetes cluster, you can use rke etcd snapshot-restore to recover your etcd. This command will revert to a specific snapshot stored in /opt/rke/etcd-snapshots that you explicitly define. During the restore process, RKE also removes the old etcd container before creating a new etcd cluster using the snapshot that you have chosen.
Warning: Restoring an etcd snapshot deletes your current etcd cluster and replaces it with a new one. Before you run the rke etcd snapshot-restore command, you should back up any important data in your cluster.
Store the snapshot externally
After taking the etcd snapshot on node2, we recommend saving this backup in a persistence place. One of the options is to save the backup on a S3 bucket or tape backup.
# If you're using an AWS host and have the ability to connect to S3
root@node2:~# s3cmd mb s3://rke-etcd-backup
Place the backup on a new node
To simulate the failure, let's power down node2.
root@node2:~# poweroff
Before restoring etcd and running rancher up, we need to retrieve the backup saved on S3 to a new node, e.g. node3.
Name
IP
Role
node1
10.0.0.1
[controlplane, worker]
node2
10.0.0.2
[etcd]
node3
10.0.0.3
[etcd]
# Make a Directory
root@node3:~# mkdir -p /opt/rke/etcdbackup
$ Get the Backup from S3
root@node3:~# s3cmd get s3://rke-etcd-backup/snapshot.db /opt/rke/etcdbackup/snapshot.db
Restore etcd on the new node from the backup
Before updating and restoring etcd, you will need to add the new node into the Kubernetes cluster with the etcd role. In the cluster.yml, comment out the old node and add in the new node. `
Finally, we need to restore the operations on the cluster by making the Kubernetes API point to the new etcd by running rke up again using the new cluster.yml.
$ rke up --config cluster.yml
Confirm that your Kubernetes cluster is functional by checking the pods on your cluster.
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发表于 2019-1-31 12:29:51
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