40 Days Of Kubernetes (35/40)

Day 35/40

Kubernetes ETCD Backup And Restore Explained

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@piyushsachdeva
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In the section we're looking at etcd backup and restore which is a very important for Kubernetes administrators.
We need to take the backup of objects.

• Get all components in yaml format into yaml file:

root@localhost:~# kubectl get all -A -o yaml > backup.yaml

It's not efficient way to backing up the cluster because we didn't backup the persistent data and some other data which is not part of these manifests.

• etcd manifest's spec

(Photo from the video)

• The /var/lib/etcd is the default directory which etcd data stores its configuration data.

• The https://127.0.0.1:2379 is where etcd client is listening and the requests of kubectl sent by api-server to this url.

• The keys of etcd that is sent are mentioned too.

  • --cert-file=/etc/kubernetes/pki/etcd/server.crt
  • --key-file=/etc/kubernetes/pki/etcd/server.key
  • --trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt

• We have 2 volume mounts:

(Photo from the video)

- `etcd-data`: /var/lib/etcd - the data directory
- `etcd-cets`: /etc/kubernetes/pki/etcd - the cert keys directory

• Install the etcdctl utility

root@localhost:~# apt install etcd-client -y

• Create an env for latest version of the utility because it uses version 2 by default.

root@localhost:~# export ETCDCTL_API=3

• Built-in snapshot source

root@localhost:~# etcdctl --endpoints=https://127.0.0.1:2379 \
--cacert=/etc/kubernetes/pki/etcd/ca.crt \
--cert=/etc/kubernetes/pki/etcd/server.crt \
--key=/etc/kubernetes/pki/etcd/server.key \
snapshot save /opt/etcd-backup.db

• Verify the snapshot

root@localhost:~# etcdctl --write-out=table snapshot status /opt/etcd-backup.db

the output would be like:

(Photo from the video)

• Let's restore the snapshot

Caution:

If any API servers are running in your cluster, you should not attempt to restore instances of etcd. Instead, follow these steps to restore etcd:

• stop all API server instances
• restore state in all etcd instances
• restart all API server instances

source

root@localhost:~# etcdctl --endpoints=https://127.0.0.1:2379 \
--cacert=/etc/kubernetes/pki/etcd/ca.crt \
--cert=/etc/kubernetes/pki/etcd/server.crt \
--key=/etc/kubernetes/pki/etcd/server.key \
snapshot restore /opt/etcd-backup.db \
--data-dir=/var/lib/etcd-restore-from-backup

Then, we need to edit the etcd manifest in /etc/kubernetes/manifests/etcd.yaml and the value of
- --data-dir option from /var/lib/etcd to /var/lib/etcd-restore-from-backup
- mountPath from /var/lib/etcd to /var/lib/etcd-restore-from-backup
- hostPath from /var/lib/etcd to /var/lib/etcd-restore-from-backup

and restart the kubelet.