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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 a database to store its contents. Now, you may want to backup both of the deployment and database together as they are parts of a single application.

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

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: minio-repo
  schedule: "*/3 * * * *"
  executionOrder: Parallel
  members:
  - target:
      alias: db
      ref:
        apiVersion: apps/v1
        kind: AppBinding
        name: wordpress-mysql
    task:
      name: mysql-backup-8.0.14
  - target:
      alias: app
      ref:
        apiVersion: apps/v1
        kind: Deployment
        name: wordpress
      volumeMounts:
      - name: wordpress-persistent-storage
        mountPath: /var/www/html
      paths:
      - /var/www/html
      exclude:
      - /var/www/html/my-file.html
      - /var/www/html/*.json
  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.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.executionOrder

spec.executionOrder specifies whether Stash should backup the targets sequentially or parallelly. If spec.executionOrder is set to Parallel, Stash will start backup of all the targets simultaneously. If it is set to Sequential, Stash will not start backup of a target until all the previous members have completed their backup process. The default value of this field is Parallel.

spec.members

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

  • target : Each member has a target specification. The target specification of a member is the same as the target specification of a BackupConfiguration explained here.

  • 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.

  • hooks : Each member has its own hook field which allows you to execute member-specific pre-backup or post-backup hooks. For more details about hooks, please visit 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 any of the members.
  • spec.hooks.postBackup: spec.hooks.postBackup hooks are executed on each backup session after taking backup of all 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.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 clean up 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 the following fields in the status section.

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

  • conditions : The status.conditions shows current backup setup condition for this BackupBatch. The following conditions are set by the Stash operator:

Condition Type Usage
RepositoryFound Indicates whether the respective Repository object was found or not.
BackendSecretFound Indicates whether the respective backend secret was found or not.
CronJobCreated Indicates whether the backup triggering CronJob was created or not.
  • memberConditions : Shows current backup setup condition of the members of a BackupBatch. Each entry has the following two fields:
    • target : Points to the respective target whose condition is shown here.
    • conditions: Shows the current backup setup condition of this member.

The following conditions are set for the members of a BackupBatch.

Condition Type Usage
BackupTargetFound Indicates whether the backup target was found or not.
StashSidecarInjected Indicates whether stash sidecar was injected into the targeted workload or not. This condition is set only for the target that uses the sidecar model.

Next Steps

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