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Restics

What is Restic

A Restic is a Kubernetes CustomResourceDefinition (CRD). It provides declarative configuration for restic in a Kubernetes native way. You only need to describe the desired backup operations in a Restic object, and the Stash operator will reconfigure the matching workloads to the desired state for you.

Restic Spec

As with all other Kubernetes objects, a Restic needs apiVersion, kind, and metadata fields. It also needs a .spec section. Below is an example Restic object.

apiVersion: stash.appscode.com/v1alpha1
kind: Restic
metadata:
  name: stash-demo
  namespace: default
spec:
  selector:
    matchLabels:
      app: stash-demo
  fileGroups:
  - path: /source/data
    retentionPolicyName: 'keep-last-5'
  backend:
    local:
      mountPath: /safe/data
      hostPath:
        path: /data/stash-test/restic-repo
    storageSecretName: stash-demo
  schedule: '@every 1m'
  volumeMounts:
  - mountPath: /source/data
    name: source-data
  retentionPolicies:
  - name: 'keep-last-5'
    keepLast: 5
    prune: true

The .spec section has following parts:

spec.selector

spec.selector is a required field that specifies a label selector for the Deployments, ReplicaSets, ReplicationControllers, DaemonSets and StatefulSets targeted by this Restic. Selectors are always matched against the labels of Deployments, ReplicaSets, ReplicationControllers, DaemonSets and StatefulSets in the same namespace as Restic object itself. You can create Deployment, etc and its matching Restic is any order. As long as the labels match, Stash operator will add sidecar container to the workload. If multiple Restic objects are matched to a given workload, Stash operator will error out and avoid adding sidecar container.

spec.type

The default value for spec.type is online. For offline backup you need to specify spec.type=offline. For more details see here.

spec.fileGroups

spec.fileGroups is a required field that specifies one or more directories that are backed up by restic. For each directory, you can specify custom tags and retention policy for snapshots.

• spec.fileGroups[].path represents a local directory that backed up by restic.
• spec.fileGroups[].tags is an optional field. This can be used to apply one or more custom tag to snapshots taken from this path.
• spec.fileGroups[].retentionPolicyName is an optional field that is used to specify a retention policy defined in spec.retentionPolicies. This defines how old snapshots are forgot by restic. If set, these options directly translate into flags for restic forget command.

spec.retentionPolicies

spec.retentionPolicies defines an array of retention policies for old snapshots. Retention policy options are below.

You can set one or more of these retention policy options together. To learn more, read here.

spec.backend

To learn how to configure various backends for Restic, please visit here.

spec.schedule

spec.schedule is a cron expression that indicates how often restic commands are invoked for file groups. At each tick, restic backup and restic forget commands are run for each of the configured file groups.

spec.paused

spec.paused can be used as enable/disable switch for Restic. The default value is false. To stop restic from taking backup set spec.paused: true. For more details see here.

spec.resources

spec.resources refers to compute resources required by the stash sidecar container. To learn more, visit here.

spec.volumeMounts

spec.volumeMounts refers to volumes to be mounted in stash sidecar to get access to fileGroup paths.

Backup Repository Structure

• For workload kind Deployment, ReplicaSet and ReplicationController restic repo is created in the sub-directory <WORKLOAD_KIND>/<WORKLOAD_NAME>. For multiple replicas, only one repository is created and sidecar is added to only one pod selected by leader-election.
• For workload kind Statefulset restic repository is created in the sub-directory <WORKLOAD_KIND>/<POD_NAME>. For multiple replicas, multiple repositories are created and sidecar is added to all pods.
• For workload kind DaemonSet restic repository is created in the sub-directory <WORKLOAD_KIND>/<WORKLOAD_NAME>/<NODE_NAME>. Separate repositories are created for each node and sidecar is added to all pods.

Prefix for Repository Directory

Stash allow the users to provide a prefix for the backup repository directory. You can provide the prefix using local.subPath for local bckend and <backend-type>.prefix for other backends in spec.backend field of Restic crd.

If you provide the prefix then the repository will be created in the following directory,

1. <PREFIX>/<WORKLOAD_KIND>/<WORKLOAD_NAME> for Deployment, ReplicaSet, ReplicationController.
2. <PREFIX>/<WORKLOAD_KIND>/<POD_NAME> for StatefulSets.
3. <PREFIX>/<WORKLOAD_KIND>/<WORKLOAD_NAME>/<NODE_NAME> for DaemonSets.

This prefix is particularly helpful when you are using a single bucket to backup your workload in the following scenario,

1. You have two or more workload with the same name but in different namespaces.
2. You have two or more cluster in different regions with the exact set-up. i.e. workload names are same in all cluster.

In these scenarios, Restic crd without a prefix will cause conflict in the repository directory in the bucket. You can overcome it using a different prefix for each workload.

Workload Annotations

For each workload where a sidecar container is added by Stash operator, the following annotations are added:

• restic.appscode.com/last-applied-configuration indicates the configuration of applied Restic CRD.
• restic.appscode.com/tag indicates the tag of appscode/stash Docker image that was added as a sidecar.

Updating Restic

The sidecar container watches for changes in the Restic fileGroups, backend and schedule. These changes are automatically applied on the next run of restic commands. If the selector of a Restic CRD is changed, Stash operator will update workload accordingly by adding/removing sidecars as required.

Disable Restic

To stop Restic from taking backup, you can do the following things:

• Set spec.paused: true in Restic yaml and then update the Restic object. This means:

  • Paused Restic CRDs will not be applied to newly created workloads.
  • Stash sidecar containers will not be removed from existing workloads but the sidecar will stop taking backup.

• Delete the Restic CRD. Stash operator will remove the sidecar container from all matching workloads.

• Change the labels of a workload. Stash operator will remove the sidecar container from that workload. This way you can selectively stop backup of a Deployment, ReplicaSet etc.

For more details about how to disable and resume Restic see here.

Next Steps

• Learn about Repository CRD here
• Learn how to use Stash to backup a Kubernetes deployment here.
• To restore a backup see here.
• Learn about the details of Recovery CRD here.
• To run backup in offline mode see here
• See the list of supported backends and how to configure them here.
• See working examples for supported workload types here.
• Thinking about monitoring your backup operations? Stash works out-of-the-box with Prometheus.
• Learn about how to configure RBAC roles.
• Want to hack on Stash? Check our contribution guidelines.