Backing up and restoring etcd on the management cluster¶

You can back up and restore etcd on the management cluster to fix failures.

Taking a snapshot of etcd for a hosted cluster¶

To back up etcd for a hosted cluster, you must take a snapshot of etcd. Later, you can restore etcd by using the snapshot.

Procedure

Stop all etcd-writer deployments by entering the following command:

$ oc scale deployment -n <hosted_cluster_namespace> --replicas=0 \
  kube-apiserver openshift-apiserver openshift-oauth-apiserver

To take an etcd snapshot, use the exec command in the etcd container by entering the following command:

$ oc exec -it <etcd_pod_name> -n <hosted_cluster_namespace> -- \
  env ETCDCTL_API=3 /usr/bin/etcdctl \
  --cacert /etc/etcd/tls/etcd-ca/ca.crt \
  --cert /etc/etcd/tls/client/etcd-client.crt \
  --key /etc/etcd/tls/client/etcd-client.key \
  --endpoints=localhost:2379 \
  snapshot save /var/lib/data/snapshot.db

To check the snapshot status, use the exec command in the etcd container by running the following command:

$ oc exec -it <etcd_pod_name> -n <hosted_cluster_namespace> -- \
  env ETCDCTL_API=3 /usr/bin/etcdctl -w table snapshot status \
  /var/lib/data/snapshot.db

Copy the snapshot data to a location where you can retrieve it later, such as an S3 bucket. See the following example.

Note

The following example uses signature version 2. If you are in a region that supports signature version 4, such as the us-east-2 region, use signature version 4. Otherwise, when copying the snapshot to an S3 bucket, the upload fails.

Example

BUCKET_NAME=somebucket
CLUSTER_NAME=cluster_name
FILEPATH="/${BUCKET_NAME}/${CLUSTER_NAME}-snapshot.db"
CONTENT_TYPE="application/x-compressed-tar"
DATE_VALUE=`date -R`
SIGNATURE_STRING="PUT\n\n${CONTENT_TYPE}\n${DATE_VALUE}\n${FILEPATH}"
ACCESS_KEY=<access_key>
SECRET_KEY=<secret>
SIGNATURE_HASH=`echo -en ${SIGNATURE_STRING} | openssl sha1 -hmac ${SECRET_KEY} -binary | base64`
HOSTED_CLUSTER_NAMESPACE=hosted_cluster_namespace

$ oc exec -it etcd-0 -n ${HOSTED_CLUSTER_NAMESPACE} -- curl -X PUT -T "/var/lib/data/snapshot.db" \
  -H "Host: ${BUCKET_NAME}.s3.amazonaws.com" \
  -H "Date: ${DATE_VALUE}" \
  -H "Content-Type: ${CONTENT_TYPE}" \
  -H "Authorization: AWS ${ACCESS_KEY}:${SIGNATURE_HASH}" \
  https://${BUCKET_NAME}.s3.amazonaws.com/${CLUSTER_NAME}-snapshot.db

To restore the snapshot on a new cluster later, save the encryption secret that the hosted cluster references.
1. Get the secret encryption key by entering the following command:
```
$ oc get -n <hosted_cluster_namespace> hostedcluster <hosted_cluster_name> \
  -o=jsonpath='{.spec.secretEncryption.aescbc}'
```
  Example output
```
{"activeKey":{"name":"<hosted_cluster_name>-etcd-encryption-key"}}
```
2. Save the secret encryption key by entering the following command:
```
$ oc get -n <hosted_cluster_namespace> secret <hosted_cluster_name>-etcd-encryption-key \
  -o=jsonpath='{.data.key}'
```
  You can decrypt this key when restoring a snapshot on a new cluster.

Restart all etcd-writer deployments by entering the following command:

$ oc scale deployment -n <control_plane_namespace> --replicas=3 \
  kube-apiserver openshift-apiserver openshift-oauth-apiserver

Next steps

Restore the etcd snapshot.

Restoring an etcd snapshot on a hosted cluster¶

If you have a snapshot of etcd from your hosted cluster, you can restore it. Currently, you can restore an etcd snapshot only during cluster creation.

To restore an etcd snapshot, you change the output from the create cluster --render command and define a restoreSnapshotURL value in the etcd section of the HostedCluster specification.

Warning

If the snapshot that you are restoring is from a hosted cluster with LoadBalancer services, the load balancer IPs might no longer be valid. In that case, you must delete and re-create the LoadBalancer services.

Prerequisites

You took an etcd snapshot on a hosted cluster.

Procedure

Delete the hosted cluster that you backed up in "Taking a snapshot of etcd for a hosted cluster" by entering the following command:
```
$ hcp destroy cluster <cluster_infra> \
  --name <hosted_cluster_name> \
  --namespace <hosted_cluster_namespace>
```
On the aws command-line interface (CLI), create a pre-signed URL so that you can download your etcd snapshot from S3 without passing credentials to the etcd deployment:
1. Define the snapshot by entering the following command:
```
$ ETCD_SNAPSHOT=${ETCD_SNAPSHOT:-"s3://${BUCKET_NAME}/${CLUSTER_NAME}-snapshot.db"}
```
2. Define the snapshot URL by entering the following command:
```
$ ETCD_SNAPSHOT_URL=$(aws s3 presign ${ETCD_SNAPSHOT})
```

Create the new hosted cluster by entering the following command:

$ hcp create cluster <platform> \
  --name <hosted_cluster_name> \
  --namespace <hosted_cluster_namespace> \
  --node-pool-replicas=2 \
  --node-upgrade-type=Replace \
  --pull-secret <path_to_pull_secret> \
  --memory <value_for_memory> \
  --cores <value_for_cpu> \
  --etcd-storage-class=gp3-csi \
  --release-image=<release_image_reference> \
  --etcd-storage-size=8Gi \
  --fips=false \
  --render \
  --render-sensitive

<hosted_cluster_name> specifies the name of the new hosted cluster. The name of the new cluster must be identical to the name of the cluster from which the etcd backup was taken.
<platform> specifies the platform you are creating the hosted cluster on, such as kubevirt or aws.
<hosted_cluster_namespace> specifies the namespace where you are creating the hosted cluster.
<path_to_pull_secret> specifies the path to your pull secret; for example, /user/name/pullsecret.
<value_for_memory> specifies the memory value, such as 8Gi.
<value_for_cpu> specifies the CPU value, such as 2.

<release_image_reference> specifies the OpenShift Container Platform release image for the cluster, for example, quay.io/openshift-release-dev/ocp-release:4.20.14-multi. You can use the --release-image flag to set up the hosted cluster with a specific OpenShift Container Platform release.

Note

The --render flag in the hcp create command does not render the secrets. To render the secrets, you must use both the --render and the --render-sensitive flags in the hcp create command.

Example output

apiVersion: v1
kind: Namespace
metadata:
  name: <hosted_cluster_namespace>
spec: {}
status: {}
---
apiVersion: v1
data:
  .dockerconfigjson: <path_to_pull_secret>
kind: Secret
metadata:
  labels:
    hypershift.openshift.io/safe-to-delete-with-cluster: "true"
  name: <hosted_cluster_name_pull_secret>
  namespace: <hosted_cluster_namespace>
---
apiVersion: hypershift.openshift.io/v1beta1
kind: HostedCluster
metadata:
  name: <hosted_cluster_name>
  namespace: <hosted_cluster_namespace>
spec:
  autoscaling: {}
  capabilities: {}
  configuration: {}
  controllerAvailabilityPolicy: HighlyAvailable
  dns:
    baseDomain: ""
  etcd:
    managed:
      storage:
        persistentVolume:
          size: 8Gi
          storageClassName: gp3-csi
        type: PersistentVolume
    managementType: Managed
  fips: false
  infraID: <hosted_cluster_name>-68tlg
  infrastructureAvailabilityPolicy: HighlyAvailable
  networking:
    clusterNetwork:
    - cidr: 10.132.0.0/14
    networkType: OVNKubernetes
    serviceNetwork:
    - cidr: 172.31.0.0/16
  olmCatalogPlacement: guest
  platform:
    kubevirt:
      baseDomainPassthrough: true
    type: KubeVirt
  pullSecret:
    name: <hosted_cluster_name_pull_secret>
  release:
    image: quay.io/openshift-release-dev/ocp-release:4.21.12-multi
  services:
  - service: APIServer
    servicePublishingStrategy:
      type: LoadBalancer
  - service: Ignition
    servicePublishingStrategy:
      type: Route
  - service: Konnectivity
    servicePublishingStrategy:
      type: Route
  - service: OAuthServer
    servicePublishingStrategy:
      type: Route
  sshKey: {}
status:
  controlPlaneEndpoint:
    host: ""
    port: 0
---
apiVersion: hypershift.openshift.io/v1beta1
kind: NodePool
metadata:
  name: <hosted_cluster_name>
  namespace: <hosted_cluster_namespace>
spec:
  arch: amd64
  clusterName: <hosted_cluster_name>
  management:
    autoRepair: false
    upgradeType: Replace
  nodeDrainTimeout: 0s
  nodeVolumeDetachTimeout: 0s
  platform:
    kubevirt:
      attachDefaultNetwork: true
      compute:
        cores: 2
        memory: 8Gi
      networkInterfaceMultiqueue: Enable
      rootVolume:
        persistent:
          size: 32Gi
        type: Persistent
    type: KubeVirt
  release:
    image: quay.io/openshift-release-dev/ocp-release:<4.x.x>-multi
  replicas: 2
status:
  replicas: 0

<hosted_cluster_namespace> specifies the name of the hosted cluster namespace.
<path_to_pull_secret> specifies the path to the pull secret.
<hosted_cluster_name_pull_secret> specifies the name of the restored pull secret for the new hosted cluster.
<hosted_cluster_name> specifies the name of the new hosted cluster. The name of the new cluster must be identical to the name of the cluster from which the etcd backup was taken.
<4.x.x> specifies the version of the release image.

Change the HostedCluster specification to refer to the URL:

spec:
  etcd:
    managed:
      storage:
        persistentVolume:
          size: 8Gi
        type: PersistentVolume
        restoreSnapshotURL:
        - "${ETCD_SNAPSHOT_URL}"
    managementType: Managed

Change the HostedCluster specification to include the new etcd encryption key:

apiVersion: v1
data:
  key: <pre_generated_etcd_encryption_key>
kind: Secret
metadata:
  labels:
    hypershift.openshift.io/safe-to-delete-with-cluster: "true"
  name: <new_hc_etcd_encryption_key>
  namespace: <hosted_cluster_namespace>
type: Opaque
---
spec:
  secretEncryption:
    aescbc:
      activeKey:
        name: <new_hc_etcd_encryption_key>
    type: aescbc

<pre_generated_etcd_encryption_key> specifies the etcd encryption key of original hosted cluster.
<new_hc_etcd_encryption_key> specifies the etcd encryption key of the new hosted cluster. Ensure that the secret that you referenced from the spec.secretEncryption.aescbc value has the same Advanced Encryption Standard (AES) key that you saved earlier.

Verification

To verify that the snapshot was restored, enter the following command:
```
$ oc logs -n <hosted_control_plane_namespace> etcd-0 -c etcd-init
```
If you use a high availability deployment, you can also check the etcd-1 and etcd-2 containers.