Category: Kubernetes Fundamentals llll

bookmark_borderBackup and Restore in Kubernetes

Posted on by Jay Jo

Backup Candidates

  • Resource Configuration deployment, service definition etc.
  • ETCD Cluster is where all cluster related information is stored.
  • Persistent Volumes, if the applications are configured with PVC.

Resource Configuration:

The declarative approach by first creating a definition file and then running kubectl apply command on the file. This is the preferred approach if you want to save the configuration. A good practice is to store files on source code repositories. That way it can be maintained by a team the source code repository should be configured with the right backup solutions.

The imperative approach

to backing up resource configuration is to use query the Kube-apiserver. Query the Kube-apiserver using kubectl or by accessing the api server directly and save all resource configurations for all objects cretaed on the cluster has a copy.

one of the commands that can be used in a backup script is to get all pods, deployments, and services in all namespaces using the kubectl uility’s get all command and extract output

$ kubectl get all --all-namespaces -o yaml > all-deploy.yaml
  • VELERO can also help.

ETCD Cluster

The ETCD cluster stores information about the state of our cluster. So information about the cluster itself, the nodes and every other resource as created within the cluster are stored.

The ETCD cluster is hosted on the master nodes. While configuring ETCD we specified a location where all the data would be stored.

$ cat /etc/kubernetes/manifests/etcd.yaml
apiVersion: v1
kind: Pod
metadata:
  annotations:
    kubeadm.kubernetes.io/etcd.advertise-client-urls: https://192.168.56.2:2379
  creationTimestamp: null
  labels:
    component: etcd
    tier: control-plane
  name: etcd
  namespace: kube-system
spec:
  containers:
  - command:
    - etcd
    - --advertise-client-urls=https://192.168.56.2:2379
    - --cert-file=/etc/kubernetes/pki/etcd/server.crt
    - --client-cert-auth=true
    - --data-dir=/var/lib/etcd
    - --initial-advertise-peer-urls=https://192.168.56.2:2380
    - --initial-cluster=kubemaster=https://192.168.56.2:2380
    - --key-file=/etc/kubernetes/pki/etcd/server.key
    - --listen-client-urls=https://127.0.0.1:2379,https://192.168.56.2:2379
    - --listen-metrics-urls=http://127.0.0.1:2381
    - --listen-peer-urls=https://192.168.56.2:2380
    - --name=kubemaster
    - --peer-cert-file=/etc/kubernetes/pki/etcd/peer.crt
    - --peer-client-cert-auth=true
    - --peer-key-file=/etc/kubernetes/pki/etcd/peer.key
    - --peer-trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    - --snapshot-count=10000
    - --trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    image: k8s.gcr.io/etcd:3.4.13-0
    imagePullPolicy: IfNotPresent
    livenessProbe:
      failureThreshold: 8
      httpGet:
        host: 127.0.0.1
        path: /health
        port: 2381
        scheme: HTTP
      initialDelaySeconds: 10
      periodSeconds: 10
      timeoutSeconds: 15
    name: etcd
    resources: {}
    startupProbe:
      failureThreshold: 24
      httpGet:
        host: 127.0.0.1
        path: /health
        port: 2381
        scheme: HTTP
      initialDelaySeconds: 10
      periodSeconds: 10
      timeoutSeconds: 15
    volumeMounts:
    - mountPath: /var/lib/etcd
      name: etcd-data
    - mountPath: /etc/kubernetes/pki/etcd
      name: etcd-certs
  hostNetwork: true
  priorityClassName: system-node-critical
  volumes:
  - hostPath:
      path: /etc/kubernetes/pki/etcd
      type: DirectoryOrCreate
    name: etcd-certs
  - hostPath:
      path: /var/lib/etcd
      type: DirectoryOrCreate
    name: etcd-data
status: {}

–data-dir=/var/lib/etcd

We specified a location where all the data would be stored. The data directory. That is the directory that can be configured to be backup by the backup tool ETCD.

Also, use snapshot command

https://etcd.io/docs/v3.3.12/op-guide/recovery/

Backup by querying the Kube-apiserver. Both of these have pros and cons. If you are using a managed kubernetes environment then at times you may not even have access to the ETCD cluster. In that case, backup by querying the kube-apiserver better way.

ANOTE.DEV