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BackupBatch

What is BackupBatch

Sometimes, a single component may not meet the requirement for your application. For example, in order to deploy a WordPress, you will need a Deployment for the WordPress and another Deployment for database to store it’s contents. Now, you may want to backup both of the deployment and database under a single configuration as they are parts of a single application.

A BackupBatch is a Kubernetes CustomResourceDefinition(CRD) which let you configure backup for multiple co-related components(workload, database etc.) under a single configuration.

BackupBatch CRD Specification

Like any official Kubernetes resource, a BackupBatch has TypeMeta, ObjectMeta, Spec and Status sections.

A sample BackupBatch object to backup multiple co-related components is shown below:

apiVersion: stash.appscode.com/v1beta1
kind: BackupBatch
metadata:
  name: deploy-backup-batch
  namespace: demo
spec:
  repository:
    name: gcs-repo
  schedule: "*/3 * * * *"
  members:
  - target:
      ref:
        apiVersion: apps/v1
        kind: AppBinding
        name: sample-mysql
    task:
      name: mysql-backup-8.0.14
  - target:
      ref:
        apiVersion: apps/v1
        kind: Deployment
        name: wordpress
      volumeMounts:
        - name: wordpress-persistent-storage
          mountPath: /var/www/html
      paths:
        - /var/www/html
  hooks:
    preBackup:
      exec:
        command:
          - /bin/sh
          - -c
          - echo "Sample PreBackup hook demo"
      containerName: my-database-container
    postBackup:
      exec:
        command:
          - /bin/sh
          - -c
          - echo "Sample PostBackup hook demo"
      containerName: my-database-container
  retentionPolicy:
    name: 'keep-last-10'
    keepLast: 10
    prune: true

Here, we are going to describe the various sections of BackupBatch crd.

BackupBatch Spec

A BackupBatch object has the following fields in the spec section.

spec.driver

spec.driver indicates the mechanism used to backup. Currently, Stash supports Restic and VolumeSnapshotter as drivers. The default value of this field is Restic. For more details, please see here.

spec.members

spec.members field specifies a list of targets to backup. Each member consists of the following fields:

• target.ref : target.ref refers to the target of backup. You have to specify apiVersion, kind and name of the target. Stash will use this information to inject a sidecar to the target or to create a backup job for it.

• target.paths : target.paths specifies list of file paths to backup.

• target.volumeMounts : target.volumeMounts are the list of volumes and their mountPaths that contain the target file paths. Stash will mount these volumes inside a sidecar container or a backup job.

• target.snapshotClassName : target.snapshotClassName indicates the VolumeSnapshotClass to use for volume snasphotting. Use this field only if driver is set to VolumeSnapshotter.

• task : task specifies the name and parameters of the Task crd to use to backup the target. For more details, please see here.

• runtimeSettings : runtimeSettings allows to configure runtime environment for the backup sidecar or job. You can specify runtime settings at both pod level and container level. For more details, please see here.

• tempDir : Stash mounts an emptyDir for holding temporary files. It is also used for caching for faster backup performance. You can configure the emptyDir using tempDir section. You can also disable caching using this field. For more details, please see here.

• interimVolumeTemplate : For some targets (i.e. some databases), Stash can’t directly pipe the dumped data to the uploading process. In this case, it has to store the dumped data temporarily before uploading to the backend. interimVolumeTemplate specifies a PVC template for holding those data temporarily. Stash will create a PVC according to the template and use it to store the data temporarily. This PVC will be deleted according to the backupHistoryLimit. For more details, please see here.

spec.hooks

spec.hooks allows performing some global actions before and after the backup process of the members. You can send HTTP requests to a remote server via httpGet or httpPost. You can check whether a TCP port is open using tcpSocket hooks. You can also execute some commands using exec hook.

• spec.hooks.preBackup: spec.hooks.preBackup hooks are executed on each backup session before taking backup of the members.
• spec.hooks.postBackup: spec.hooks.postBackup hooks are executed on each backup session after taking backup of the members.

For more details on how hooks work in Stash and how to configure different types of hook, please visit here.

spec.runtimeSettings

spec.runtimeSettings This runtime settings is applicable for CronJob(used to create BackupSession) only. For more details, please see here.

spec.repository

spec.repository.name indicates the Repository crd name that holds necessary backend information where the backed up data will be stored.

spec.schedule

spec.schedule is a cron expression that specifies the schedule of backup. Stash creates a Kubernetes CronJob with this schedule.

spec.backupHistoryLimit

spec.backupHistoryLimit specifies the number of BackupSession and its associate resources (Job, PVC etc.) to keep for debugging purposes. The default value of this field is 1. Stash will cleanup the old BackupSession and it’s associate resources after each backup session according to backupHistoryLimit.

spec.paused

spec.paused can be used as enable/disable switch for backup. If it is set true, Stash will not take any backup of the target specified by this BackupBatch.

spec.retentionPolicy

spec.retentionPolicy specifies the policy to follow for cleaning old snapshots. For more details, please see here.

BackupBatch Status

A BackupBatch object has only a observedGeneration field in the status section.

• observedGeneration : The most recent generation observed by the BackupBatch controller.

Next Steps

• Learn how to configure BackupBatch to backup data from here.