Restoring virtual machines - Backup and restore | Virtualization | OpenShift Container Platform 4.11

Creating a Restore CR
- Creating restore hooks

You restore an OpenShift API for Data Protection (OADP) Backup custom resource (CR) by creating a Restore CR.

You can add hooks to the Restore CR to run commands in init containers, before the application container starts, or in the application container itself.

Creating a Restore CR

You restore a Backup custom resource (CR) by creating a Restore CR.

Prerequisites

You must install the OpenShift API for Data Protection (OADP) Operator.
The DataProtectionApplication CR must be in a Ready state.
You must have a Velero Backup CR.
Adjust the requested size so the persistent volume (PV) capacity matches the requested size at backup time.

Procedure

Create a Restore CR, as in the following example:

apiVersion: velero.io/v1
kind: Restore
metadata:
  name: <restore>
  namespace: openshift-adp
spec:
  backupName: <backup> (1)
  includedResources: [] (2)
  excludedResources:
  - nodes
  - events
  - events.events.k8s.io
  - backups.velero.io
  - restores.velero.io
  - resticrepositories.velero.io
  restorePVs: true (3)

1	Name of the `Backup` CR.
2	Optional: Specify an array of resources to include in the restore process. Resources might be shortcuts (for example, `po` for `pods`) or fully-qualified. If unspecified, all resources are included.
3	Optional: The `restorePVs` parameter can be set to `false` in order to turn off restore of `PersistentVolumes` from `VolumeSnapshot` of Container Storage Interface (CSI) snapshots, or from native snapshots when `VolumeSnapshotLocation` is configured.

Verify that the status of the Restore CR is Completed by entering the following command:
```
$ oc get restore -n openshift-adp <restore> -o jsonpath='{.status.phase}'
```
Verify that the backup resources have been restored by entering the following command:
```
$ oc get all -n <namespace> (1)
```
1 Namespace that you backed up.

If you use Restic to restore DeploymentConfig objects or if you use post-restore hooks, run the dc-restic-post-restore.sh cleanup script by entering the following command:

$ bash dc-restic-post-restore.sh <restore-name>

In the course of the restore process, the OADP Velero plug-ins scale down the DeploymentConfig objects and restore the pods as standalone pods to prevent the cluster from deleting the restored DeploymentConfig pods immediately on restore and to allow Restic and post-restore hooks to complete their actions on the restored pods. The cleanup script removes these disconnected pods and scale any DeploymentConfig objects back up to the appropriate number of replicas.

dc-restic-post-restore.sh cleanup script

#!/bin/bash
set -e

# if sha256sum exists, use it to check the integrity of the file
if command -v sha256sum >/dev/null 2>&1; then
  CHeCKSUM_CMD="sha256sum"
else
  CHeCKSUM_CMD="shasum -a 256"
fi

label_name () {
    if [ "${#1}" -le "63" ]; then
	echo $1
	return
    fi
    sha=$(echo -n $1|$CHeCKSUM_CMD)
    echo "${1:0:57}${sha:0:6}"
}

OADP_NAMeSPACe=${OADP_NAMeSPACe:=openshift-adp}

if [[ $# -ne 1 ]]; then
    echo "usage: ${BASH_SOURCe} restore-name"
    exit 1
fi

echo using OADP Namespace $OADP_NAMeSPACe
echo restore: $1

label=$(label_name $1)
echo label: $label

echo Deleting disconnected restore pods
oc delete pods -l oadp.openshift.io/disconnected-from-dc=$label

for dc in $(oc get dc --all-namespaces -l oadp.openshift.io/replicas-modified=$label -o jsonpath='{range .items[*]}{.metadata.namespace}{","}{.metadata.name}{","}{.metadata.annotations.oadp\.openshift\.io/original-replicas}{","}{.metadata.annotations.oadp\.openshift\.io/original-paused}{"\n"}')
do
    IFS=',' read -ra dc_arr <<< "$dc"
    if [ ${#dc_arr[0]} -gt 0 ]; then
	echo Found deployment ${dc_arr[0]}/${dc_arr[1]}, setting replicas: ${dc_arr[2]}, paused: ${dc_arr[3]}
	cat <<eOF | oc patch dc  -n ${dc_arr[0]} ${dc_arr[1]} --patch-file /dev/stdin
spec:
  replicas: ${dc_arr[2]}
  paused: ${dc_arr[3]}
eOF
    fi
done

Creating restore hooks

You create restore hooks to run commands in a container in a pod while restoring your application by editing the Restore custom resource (CR).

You can create two types of restore hooks:

An init hook adds an init container to a pod to perform setup tasks before the application container starts.

If you restore a Restic backup, the restic-wait init container is added before the restore hook init container.
An exec hook runs commands or scripts in a container of a restored pod.

Procedure

Add a hook to the spec.hooks block of the Restore CR, as in the following example:

apiVersion: velero.io/v1
kind: Restore
metadata:
  name: <restore>
  namespace: openshift-adp
spec:
  hooks:
    resources:
      - name: <hook_name>
        includedNamespaces:
        - <namespace> (1)
        excludedNamespaces:
        - <namespace>
        includedResources:
        - pods (2)
        excludedResources: []
        labelSelector: (3)
          matchLabels:
            app: velero
            component: server
        postHooks:
        - init:
            initContainers:
            - name: restore-hook-init
              image: alpine:latest
              volumeMounts:
              - mountPath: /restores/pvc1-vm
                name: pvc1-vm
              command:
              - /bin/ash
              - -c
            timeout: (4)
        - exec:
            container: <container> (5)
            command:
            - /bin/bash (6)
            - -c
            - "psql < /backup/backup.sql"
            waitTimeout: 5m (7)
            execTimeout: 1m (8)
            onerror: Continue (9)

1	Optional: Array of namespaces to which the hook applies. If this value is not specified, the hook applies to all namespaces.
2	Currently, pods are the only supported resource that hooks can apply to.
3	Optional: This hook only applies to objects matching the label selector.
4	Optional: Timeout specifies the maximum amount of time Velero waits for `initContainers` to complete.
5	Optional: If the container is not specified, the command runs in the first container in the pod.
6	This is the entrypoint for the init container being added.
7	Optional: How long to wait for a container to become ready. This should be long enough for the container to start and for any preceding hooks in the same container to complete. If not set, the restore process waits indefinitely.
8	Optional: How long to wait for the commands to run. The default is `30s`.
9	Allowed values for error handling are `Fail` and `Continue`: `Continue`: Only command failures are logged. `Fail`: No more restore hooks run in any container in any pod. The status of the `Restore` CR will be `PartiallyFailed`.