# Restic Integration

As of version 0.9.0, Velero has support for backing up and restoring Kubernetes volumes using a free open-source backup tool called 
[restic][1].

Velero has always allowed you to take snapshots of persistent volumes as part of your backups if you’re using one of 
the supported cloud providers’ block storage offerings (Amazon EBS Volumes, Azure Managed Disks, Google Persistent Disks). 
Starting with version 0.6.0, we provide a plugin model that enables anyone to implement additional object and block storage 
backends, outside the main Velero repository.

We integrated restic with Velero so that users have an out-of-the-box solution for backing up and restoring almost any type of Kubernetes
volume*. This is a new capability for Velero, not a replacement for existing functionality. If you're running on AWS, and
taking EBS snapshots as part of your regular Velero backups, there's no need to switch to using restic. However, if you've
been waiting for a snapshot plugin for your storage platform, or if you're using EFS, AzureFile, NFS, emptyDir, 
local, or any other volume type that doesn't have a native snapshot concept, restic might be for you.

Restic is not tied to a specific storage platform, which means that this integration also paves the way for future work to enable
cross-volume-type data migrations. Stay tuned as this evolves!

\* hostPath volumes are not supported, but the [new local volume type][4] is supported.

## Setup

### Prerequisites

- A working install of Velero version 0.10.0 or later. See [Set up Velero][2]
- A local clone of [the latest release tag of the Velero repository][3]
- Velero's restic integration requires the Kubernetes [MountPropagation feature][6], which is enabled by default in Kubernetes v1.10.0 and later.


### Instructions

1. Ensure you've [downloaded & extracted the latest release][3].

1. In the Velero directory (i.e. where you extracted the release tarball), run the following to create new custom resource definitions:

    ```bash
    kubectl apply -f config/common/00-prereqs.yaml
    ```

1. Run one of the following for your platform to create the daemonset:

    - AWS: `kubectl apply -f config/aws/20-restic-daemonset.yaml`
    - Azure: `kubectl apply -f config/azure/20-restic-daemonset.yaml`
    - GCP: `kubectl apply -f config/gcp/20-restic-daemonset.yaml`
    - Minio: `kubectl apply -f config/minio/30-restic-daemonset.yaml`

You're now ready to use Velero with restic.

## Back up

1. Run the following for each pod that contains a volume to back up:

    ```bash
    kubectl -n YOUR_POD_NAMESPACE annotate pod/YOUR_POD_NAME backup.velero.io/backup-volumes=YOUR_VOLUME_NAME_1,YOUR_VOLUME_NAME_2,...
    ```

    where the volume names are the names of the volumes in the pod spec. 
    
    For example, for the following pod:

    ```bash
    apiVersion: v1
    kind: Pod
    metadata:
      name: sample
      namespace: foo
    spec:
      containers:
      - image: k8s.gcr.io/test-webserver
        name: test-webserver
        volumeMounts:
        - name: pvc-volume
          mountPath: /volume-1
        - name: emptydir-volume
          mountPath: /volume-2
      volumes:
      - name: pvc-volume
        persistentVolumeClaim: 
          claimName: test-volume-claim
      - name: emptydir-volume
        emptyDir: {}
    ```

    You'd run:
    ```bash
    kubectl -n foo annotate pod/sample backup.velero.io/backup-volumes=pvc-volume,emptydir-volume
    ```

    This annotation can also be provided in a pod template spec if you use a controller to manage your pods.

1. Take an Velero backup:

    ```bash
    velero backup create NAME OPTIONS...
    ```

1. When the backup completes, view information about the backups:

    ```bash
    velero backup describe YOUR_BACKUP_NAME

    kubectl -n velero get podvolumebackups -l velero.io/backup-name=YOUR_BACKUP_NAME -o yaml
    ```

## Restore

1. Restore from your Velero backup:

    ```bash
    velero restore create --from-backup BACKUP_NAME OPTIONS...
    ```

1. When the restore completes, view information about your pod volume restores:
    
    ```bash
    velero restore describe YOUR_RESTORE_NAME

    kubectl -n velero get podvolumerestores -l velero.io/restore-name=YOUR_RESTORE_NAME -o yaml
    ```

## Limitations

- `hostPath` volumes are not supported. [Local persistent volumes][4] are supported.
- Those of you familiar with [restic][1] may know that it encrypts all of its data. We've decided to use a static, 
common encryption key for all restic repositories created by Velero. **This means that anyone who has access to your
bucket can decrypt your restic backup data**. Make sure that you limit access to the restic bucket
appropriately. We plan to implement full Velero backup encryption, including securing the restic encryption keys, in 
a future release.   

## Troubleshooting

Run the following checks:

Are your Velero server and daemonset pods running?

```bash
kubectl get pods -n velero
```

Does your restic repository exist, and is it ready?

```bash
velero restic repo get

velero restic repo get REPO_NAME -o yaml
```

Are there any errors in your Velero backup/restore?

```bash
velero backup describe BACKUP_NAME
velero backup logs BACKUP_NAME

velero restore describe RESTORE_NAME
velero restore logs RESTORE_NAME
```

What is the status of your pod volume backups/restores?

```bash
kubectl -n velero get podvolumebackups -l velero.io/backup-name=BACKUP_NAME -o yaml

kubectl -n velero get podvolumerestores -l velero.io/restore-name=RESTORE_NAME -o yaml
```

Is there any useful information in the Velero server or daemon pod logs?

```bash
kubectl -n velero logs deploy/velero
kubectl -n velero logs DAEMON_POD_NAME
```

**NOTE**: You can increase the verbosity of the pod logs by adding `--log-level=debug` as an argument
to the container command in the deployment/daemonset pod template spec.

## How backup and restore work with restic

We introduced three custom resource definitions and associated controllers:

- `ResticRepository` - represents/manages the lifecycle of Velero's [restic repositories][5]. Velero creates
a restic repository per namespace when the first restic backup for a namespace is requested. The controller
for this custom resource executes restic repository lifecycle commands -- `restic init`, `restic check`,
and `restic prune`.

    You can see information about your Velero restic repositories by running `velero restic repo get`.

- `PodVolumeBackup` - represents a restic backup of a volume in a pod. The main Velero backup process creates
one or more of these when it finds an annotated pod. Each node in the cluster runs a controller for this
resource (in a daemonset) that handles the `PodVolumeBackups` for pods on that node. The controller executes
`restic backup` commands to backup pod volume data. 

- `PodVolumeRestore` - represents a restic restore of a pod volume. The main Velero restore process creates one
or more of these when it encounters a pod that has associated restic backups. Each node in the cluster runs a 
controller for this resource (in the same daemonset as above) that handles the `PodVolumeRestores` for pods 
on that node. The controller executes `restic restore` commands to restore pod volume data.

### Backup

1. The main Velero backup process checks each pod that it's backing up for the annotation specifying a restic backup
should be taken (`backup.velero.io/backup-volumes`)
1. When found, Velero first ensures a restic repository exists for the pod's namespace, by:
    - checking if a `ResticRepository` custom resource already exists
    - if not, creating a new one, and waiting for the `ResticRepository` controller to init/check it
1. Velero then creates a `PodVolumeBackup` custom resource per volume listed in the pod annotation
1. The main Velero process now waits for the `PodVolumeBackup` resources to complete or fail
1. Meanwhile, each `PodVolumeBackup` is handled by the controller on the appropriate node, which:
    - has a hostPath volume mount of `/var/lib/kubelet/pods` to access the pod volume data
    - finds the pod volume's subdirectory within the above volume
    - runs `restic backup`
    - updates the status of the custom resource to `Completed` or `Failed`
1. As each `PodVolumeBackup` finishes, the main Velero process captures its restic snapshot ID and adds it as an annotation
to the copy of the pod JSON that's stored in the Velero backup. This will be used for restores, as seen in the next section.

### Restore

1. The main Velero restore process checks each pod that it's restoring for annotations specifying a restic backup
exists for a volume in the pod (`snapshot.velero.io/<volume-name>`)
1. When found, Velero first ensures a restic repository exists for the pod's namespace, by:
    - checking if a `ResticRepository` custom resource already exists
    - if not, creating a new one, and waiting for the `ResticRepository` controller to init/check it (note that
    in this case, the actual repository should already exist in object storage, so the Velero controller will simply
    check it for integrity)
1. Velero adds an init container to the pod, whose job is to wait for all restic restores for the pod to complete (more
on this shortly)
1. Velero creates the pod, with the added init container, by submitting it to the Kubernetes API
1. Velero creates a `PodVolumeRestore` custom resource for each volume to be restored in the pod
1. The main Velero process now waits for each `PodVolumeRestore` resource to complete or fail
1. Meanwhile, each `PodVolumeRestore` is handled by the controller on the appropriate node, which:
    - has a hostPath volume mount of `/var/lib/kubelet/pods` to access the pod volume data
    - waits for the pod to be running the init container
    - finds the pod volume's subdirectory within the above volume
    - runs `restic restore`
    - on success, writes a file into the pod volume, in a `.velero` subdirectory, whose name is the UID of the Velero restore
    that this pod volume restore is for
    - updates the status of the custom resource to `Completed` or `Failed`
1. The init container that was added to the pod is running a process that waits until it finds a file
within each restored volume, under `.velero`, whose name is the UID of the Velero restore being run
1. Once all such files are found, the init container's process terminates successfully and the pod moves
on to running other init containers/the main containers.


[1]: https://github.com/restic/restic
[2]: install-overview.md
[3]: https://github.com/heptio/velero/releases/
[4]: https://kubernetes.io/docs/concepts/storage/volumes/#local
[5]: http://restic.readthedocs.io/en/latest/100_references.html#terminology
[6]: https://kubernetes.io/docs/concepts/storage/volumes/#mount-propagation
