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etcd-backup-and-restore.md

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1. Get etcdctl utility if it's not already present.

Reference: https://github.com/etcd-io/etcd/releases

ETCD_VER=v3.3.13

# choose either URL
GOOGLE_URL=https://storage.googleapis.com/etcd
GITHUB_URL=https://github.com/etcd-io/etcd/releases/download
DOWNLOAD_URL=${GOOGLE_URL}

rm -f /tmp/etcd-${ETCD_VER}-linux-amd64.tar.gz
rm -rf /tmp/etcd-download-test && mkdir -p /tmp/etcd-download-test

curl -L ${DOWNLOAD_URL}/${ETCD_VER}/etcd-${ETCD_VER}-linux-amd64.tar.gz -o /tmp/etcd-${ETCD_VER}-linux-amd64.tar.gz
tar xzvf /tmp/etcd-${ETCD_VER}-linux-amd64.tar.gz -C /tmp/etcd-download-test --strip-components=1
rm -f /tmp/etcd-${ETCD_VER}-linux-amd64.tar.gz

/tmp/etcd-download-test/etcd --version
ETCDCTL_API=3 /tmp/etcd-download-test/etcdctl version

mv /tmp/etcd-download-test/etcdctl /usr/bin

2. Backup

ETCDCTL_API=3 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 /tmp/snapshot-pre-boot.db

-----------------------------

Disaster Happens

-----------------------------

3. Restore ETCD Snapshot to a new folder

ETCDCTL_API=3 etcdctl --endpoints=https://[127.0.0.1]:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt \
     --name=master \
     --cert=/etc/kubernetes/pki/etcd/server.crt --key=/etc/kubernetes/pki/etcd/server.key \
     --data-dir /var/lib/etcd-from-backup \
     --initial-cluster=master=https://127.0.0.1:2380 \
     --initial-cluster-token etcd-cluster-1 \
     --initial-advertise-peer-urls=https://127.0.0.1:2380 \
     snapshot restore /tmp/snapshot-pre-boot.db

4. Modify /etc/kubernetes/manifests/etcd.yaml

Update ETCD POD to use the new data directory and cluster token by modifying the pod definition file at /etc/kubernetes/manifests/etcd.yaml. When this file is updated, the ETCD pod is automatically re-created as thisis a static pod placed under the /etc/kubernetes/manifests directory.

Update --data-dir to use new target location

--data-dir=/var/lib/etcd-from-backup

Update new initial-cluster-token to specify new cluster

--initial-cluster-token=etcd-cluster-1

Update volumes and volume mounts to point to new path

    volumeMounts:
    - mountPath: /var/lib/etcd-from-backup
      name: etcd-data
    - mountPath: /etc/kubernetes/pki/etcd
      name: etcd-certs
  hostNetwork: true
  priorityClassName: system-cluster-critical
  volumes:
  - hostPath:
      path: /var/lib/etcd-from-backup
      type: DirectoryOrCreate
    name: etcd-data
  - hostPath:
      path: /etc/kubernetes/pki/etcd
      type: DirectoryOrCreate
    name: etcd-certs

Note: You don't really need to update data directory and volumeMounts.mountPath path above. You could simply just update the hostPath.path in the volumes section to point to the new directory. But if you are not working with a kubeadm deployed cluster, then you might have to update the data directory. That's why I left it as is.