How do I back up and restore Kubernetes configurations?

Backing up and restoring Kubernetes configurations is a critical task to ensure business continuity and disaster recovery. Here’s how you can approach it:

Backup Kubernetes Configurations

Kubernetes configurations are primarily stored in etcd, the key-value store that Kubernetes uses as its backing store. Additionally, you may want to back up application manifests, custom resource definitions (CRDs), and other cluster-level configurations. Here’s a step-by-step guide:

1. Backup etcd Data

etcd contains all the cluster state and configurations, such as secrets, deployments, services, and more. Backing up etcd is essential for a full cluster recovery.

Steps:
– Connect to the etcd instance running in the control plane.
– Use the etcdctl tool to take a snapshot:
bash ETCDCTL_API=3 etcdctl \ --endpoints=https://127.0.0.1:2379 \ --cert=/etc/kubernetes/pki/etcd/server.crt \ --key=/etc/kubernetes/pki/etcd/server.key \ --cacert=/etc/kubernetes/pki/etcd/ca.crt \ snapshot save /path/to/backup/etcd-snapshot.db
Replace /path/to/backup/etcd-snapshot.db with the desired path to store the backup file.

Automate backups: Schedule periodic backups using a cron job or systemd timer.

2. Backup Kubernetes YAML Manifests

In addition to etcd, you should back up the YAML manifests for your workloads (e.g., deployments, services, ingresses).

Steps:
– Export resources using kubectl:
bash kubectl get all --all-namespaces -o yaml > all-resources-backup.yaml kubectl get crd -o yaml > crds-backup.yaml
– Store these files in a version-controlled system like Git or a backup location.

3. Backup Secrets

Secrets are stored in etcd but are encrypted. You can export them for backup purposes:
bash kubectl get secrets --all-namespaces -o yaml > secrets-backup.yaml
Be careful with security; encrypt these backups when storing them.

4. Consider a Kubernetes Backup Tool

Several tools can automate backups and provide advanced features:
– Velero: Open-source solution for backing up and restoring Kubernetes resources and persistent volumes.
– Kasten K10: A commercial backup solution for Kubernetes.
– Stash: A Kubernetes-native backup solution.

These tools can simplify the process and also handle persistent volume backups.

Restore Kubernetes Configurations

Restoring Kubernetes configurations involves rehydrating etcd, reapplying resource YAML manifests, and recovering persistent volumes if needed.

1. Restore etcd Data

Stop the Kubernetes control plane components (e.g., kube-apiserver, kube-scheduler, kube-controller-manager).
Restore the etcd snapshot:
bash ETCDCTL_API=3 etcdctl snapshot restore /path/to/backup/etcd-snapshot.db \ --data-dir /var/lib/etcd
Replace /var/lib/etcd with the directory where etcd stores its data.
Restart the control plane components.

2. Reapply Kubernetes Manifests

Reapply backed-up YAML manifests:
bash kubectl apply -f all-resources-backup.yaml kubectl apply -f crds-backup.yaml kubectl apply -f secrets-backup.yaml

3. Restore Persistent Volumes

If using tools like Velero or Kasten, follow their documentation to restore persistent volumes.
If manually restoring, ensure that the underlying storage (e.g., NFS, Ceph) is intact and mount the volumes to the respective pods.

4. Verify Cluster State

Check the cluster health:
bash kubectl get nodes kubectl get pods --all-namespaces
Validate that workloads are running and data integrity is intact.

Best Practices

Automate Backup Process: Use tools like Velero or cron jobs to automate backups.
Secure Backup Files: Encrypt sensitive backups (e.g., secrets, etcd snapshots) and store them securely.
Test Restores Regularly: Periodically test the restore process to ensure backups are usable.
Version Control for Manifests: Store Kubernetes manifests in Git or another version-controlled system for easy tracking.
Document the Process: Create and maintain documentation for backup and restore procedures.

Would you like additional guidance on backup tools or specific configurations for your environment?