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Sending Backup Notification to Slack Channel

In this guide, we are going to show you how to send backup notifications to a Slack channel. Here, we are going to use Slack Incoming Webhook to send the notification.

Before You Begin

At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.
Install KubeStash in your cluster following the steps here.
If you haven’t read about how hooks work in KubeStash, please check it from here.

You should be familiar with the following KubeStash concepts:

To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Configure Slack Incoming Webhook

At first, let’s configure a Slack incoming webhook. We are going to send the notifications to a channel named testing. Now, follow the steps below:

Go to https://api.slack.com/messaging/webhooks and click the Create your Slack app button as shown in the following image.

We are going to build a new app. So, select the From scratch option as below.

Now, give your app a name and select your workspace.

Then, select your application type as Incoming Webhooks.

Now, activate your incoming webhook.

Scroll down and click on the Add New Webhook to Workspace button.

Now, select your desired Slack channel where you want to send the notifications. Then, click on the Allow button.

Finally, copy the webhook path starting from /service/****. We will use this path in our hook specification.

Our Slack incoming webhook is ready to receive notifications. In the next section, we are going to configure a Stash webhook to send backup notifications to this incoming webhook.

Prepare Application

Now, let’s deploy a sample application and generate some sample data for it. Here, is the YAML of a DaemonSet that we are going to deploy:

apiVersion: apps/v1
kind: DaemonSet
metadata:
  labels:
    app: ks-demo
  name: ks-demo
  namespace: demo
spec:
  selector:
    matchLabels:
      app: ks-demo
  template:
    metadata:
      labels:
        app: ks-demo
      name: busybox
    spec:
      containers:
        - args: ["echo sample_data > /source/data/data.txt && sleep 3000"]
          command: ["/bin/sh", "-c"]
          image: busybox
          imagePullPolicy: IfNotPresent
          name: busybox
          volumeMounts:
            - mountPath: /source/data
              name: source-data
      restartPolicy: Always
      volumes:
        - name: source-data
          hostPath:
            path: /kubestash/source/data

Let’s deploy the above DaemonSet.

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/hooks/slack-notification/examples/daemonset.yaml
daemonset.apps/ks-demo created

Let’s verify that the sample data has been created successfully:

$ kubectl exec -n demo ks-demo-b4mxd -- ls /source/data
data.txt

Our application is ready with some sample data. In the next section, we are going to setup a backup for this application.

Prepare Backend

We are going to store our backed up data into a GCS bucket. We have to create a Secret with necessary credentials and a BackupStorage crd to use this backend. If you want to use a different backend, please read the respective backend configuration doc from here.

Create Secret:

Let’s create a secret called gcs-secret with access credentials to our desired GCS bucket,

$ echo -n '<your-project-id>' > GOOGLE_PROJECT_ID
$ cat /path/to/downloaded-sa-key.json > GOOGLE_SERVICE_ACCOUNT_JSON_KEY
$ kubectl create secret generic -n demo gcs-secret \
    --from-file=./GOOGLE_PROJECT_ID \
    --from-file=./GOOGLE_SERVICE_ACCOUNT_JSON_KEY
secret/gcs-secret created

Create BackupStorage:

Now, create a BackupStorage using this secret. Below is the YAML of BackupStorage crd we are going to create,

apiVersion: storage.kubestash.com/v1alpha1
kind: BackupStorage
metadata:
  name: gcs-storage
  namespace: demo
spec:
  storage:
    provider: gcs
    gcs:
      bucket: kubestash-qa
      prefix: demo
      secretName: gcs-secret
  usagePolicy:
    allowedNamespaces:
      from: All
  default: true
  deletionPolicy: WipeOut

Let’s create the BackupStorage we have shown above,

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/hooks/slack-notification/examples/backupstorage.yaml
backupstorage.storage.kubestash.com/gcs-storage created

Now, we are ready to backup our sample data into this backend.

Create RetentionPolicy:

Now, let’s create a RetentionPolicy to specify how the old Snapshots should be cleaned up.

Below is the YAML of the RetentionPolicy object that we are going to create,

apiVersion: storage.kubestash.com/v1alpha1
kind: RetentionPolicy
metadata:
  name: demo-retention
  namespace: demo
spec:
  default: true
  failedSnapshots:
    last: 2
  maxRetentionPeriod: 2mo
  successfulSnapshots:
    last: 5
  usagePolicy:
    allowedNamespaces:
      from: All

Notice the spec.usagePolicy that allows referencing the RetentionPolicy from all namespaces. To allow specific namespaces, we can configure it accordingly by following RetentionPolicy usage policy.

Let’s create the above RetentionPolicy,

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/hooks/slack-notification/examples/retentionpolicy.yaml
retentionpolicy.storage.kubestash.com/demo-retention created

Backup

In this section, we are going to setup a backup for the application we deployed earlier. We are going to configure a postBackup hook to send a notification to our Slack incoming webhook when a backup session completes.

Create HookTemplate

Below is the YAML of the HookTemplate CR to notify all backup notification in slack ,

apiVersion: core.kubestash.com/v1alpha1
kind: HookTemplate
metadata:
  name: slack-hook
  namespace: demo
spec:
  usagePolicy:
    allowedNamespaces:
      from: All
  action:
    httpPost:
      host: hooks.slack.com
      path: /services/XX/XX/XX # provide webhook URL starting from "/services/****"
      port: 443
      scheme: HTTPS
      httpHeaders:
        - name: Content-Type
          value: application/json
      body: |
        {{$msg := dict "type" "mrkdwn" "text" "ooo"}}{{if eq .Status.Phase "Succeeded"}}{{- $msg = dict  "type" "mrkdwn" "text" (printf "Backup completed for %s/%s Status: %s." .Namespace .Target.Name .Status.Phase) -}}{{else}}{{- $msg = dict  "type" "mrkdwn" "text" (printf "Backup failed for %s/%s Status: %s." .Namespace .Target.Name .Status.Error) -}}{{end}}
          {
            "blocks": [
                {
                  "type": "section",
                  "text": {{ toJson $msg }}
                }
              ]
          }        
  executor:
    type: Operator

Here we have setup an action to send an HTTP POST request. In the path field of the httpPost section, we have specified the Slack incoming webhook path that we copied in the last step of configuring Slack incoming webhook.

Let’s create the above HookTemplate,

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/hooks/slack-notification/examples/hooktemplate.yaml
hooktemplate.core.kubestash.com/slack-hook created

Now, we need to create a secret with a Restic password for backup data encryption.

Create Secret:

Let’s create a secret called encrypt-secret with the Restic password,

$ echo -n 'changeit' > RESTIC_PASSWORD
$ kubectl create secret generic -n demo encrypt-secret \
    --from-file=./RESTIC_PASSWORD \
secret "encrypt-secret" created

Here, is the YAML of the BackupConfiguration that we are going to create:

apiVersion: core.kubestash.com/v1alpha1
kind: BackupConfiguration
metadata:
  name: sample-backup
  namespace: demo
spec:
  target:
    apiGroup: apps
    kind: DaemonSet
    name: ks-demo
    namespace: demo
  backends:
    - name: gcs-backend
      storageRef:
        namespace: demo
        name: gcs-storage
      retentionPolicy:
        name: demo-retention
        namespace: demo
  sessions:
    - name: frequent-backup
      sessionHistoryLimit: 3
      scheduler:
        schedule: "*/5 * * * *"
        jobTemplate:
          backoffLimit: 1
      hooks:
        postBackup:
          - name: slack-notification
            hookTemplate:
              name: slack-hook
              namespace: demo
            maxRetry: 3
            timeout: 30s
      repositories:
        - name: daemon-repo
          backend: gcs-backend
          directory: /demo/daemon
          encryptionSecret:
            name: encrypt-secret
            namespace: demo
      addon:
        name: workload-addon
        tasks:
          - name: logical-backup
            params:
              paths: /source/data
      retryConfig:
        maxRetry: 2
        delay: 1m

Notice the hooks section. We have specified the HookTemplate as the postBackup hook for this BackupConfiguration.

Also, notice the body field of the httpPost section. We have used Go template to include information about the backup target and status.

Let’s create the BackupConfiguration we have shown above,

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/hooks/slack-notification/examples/all_backup_notification.yaml
backupconfiguration.core.kubestash.com/sample-backup created

Wait for BackupSession:

Now, let’s wait for a BackupSession. Run the following command to watch for BackupSession.

$ kubectl get backupsession --all-namespaces -w
NAMESPACE   NAME                                       INVOKER-TYPE          INVOKER-NAME    PHASE       DURATION   AGE
demo        sample-backup-frequent-backup-1708411503   BackupConfiguration   sample-backup   Succeeded              10m

We can see from the above output that the backup session has succeeded.

Verify Notification:

Now, if we go to the Slack channel we have configured for notification. We should see a notification similar to this:

Sending Only Backup Failure Notification

Create HookTemplate

Below is the YAML of the HookTemplate CR to notify only failed backup notification in slack ,

apiVersion: core.kubestash.com/v1alpha1
kind: HookTemplate
metadata:
  name: slack-hook
  namespace: demo
spec:
  usagePolicy:
    allowedNamespaces:
      from: All
  action:
    httpPost:
      host: hooks.slack.com
      path: /services/XX/XX/XX # provide webhook URL starting from "/services/****"
      port: 443
      scheme: HTTPS
      httpHeaders:
        - name: Content-Type
          value: application/json
      body: |
        {{- $msg := dict  "type" "mrkdwn" "text" (printf "Backup failed for %s/%s Status: %s." .Namespace .Target.Name .Status.Error) -}}
          {
            "blocks": [
                {
                  "type": "section",
                  "text": {{ toJson $msg }}
                }
              ]
          }        
  executor:
    type: Operator

Let’s create the above HookTemplate,

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/hooks/slack-notification/examples/hooktemplate_failed.yaml
hooktemplate.core.kubestash.com/slack-hook configured

We can also use the executionPolicy to send notification only for the failed backups. Check the following BackupConfiguration:

apiVersion: core.kubestash.com/v1alpha1
kind: BackupConfiguration
metadata:
  name: sample-backup
  namespace: demo
spec:
  target:
    apiGroup: apps
    kind: DaemonSet
    name: ks-demo
    namespace: demo
  backends:
    - name: gcs-backend
      storageRef:
        namespace: demo
        name: gcs-storage
      retentionPolicy:
        name: demo-retention
        namespace: demo
  sessions:
    - name: frequent-backup
      sessionHistoryLimit: 3
      scheduler:
        schedule: "*/5 * * * *"
        jobTemplate:
          backoffLimit: 1
      hooks:
        postBackup:
          - name: slack-notification
            hookTemplate:
              name: slack-hook
              namespace: demo
            maxRetry: 3
            timeout: 30s
            executionPolicy: OnFailure
      repositories:
        - name: daemon-repo
          backend: gcs-backend
          directory: /demo/daemon
          encryptionSecret:
            name: encrypt-secret
            namespace: demo
      addon:
        name: workload-addon
        tasks:
          - name: logical-backup
            params:
              paths: /wrong/data
      retryConfig:
        maxRetry: 2
        delay: 1m

Here, we have provided an invalid path in the paths field of the target section. This will force the backup to fail.

Notice that, this time we have specified the executionPolicy field to OnFailure. This will tell KubeStash to send the notification only if the backup fails. In the message body, we have included information about target and reason of the failure.

Let’s apply the above BackupConfiguration:

$ kubectl apply -f https://github.com/kubestash/docs/raw/v2024.8.14/docs/guides/hooks/slack-notification/examples/failed_backup_notification.yaml
backupconfiguration.core.kubestash.com/sample-backup configured

Wait for BackupSession:

Again, let’s wait for a scheduled backup. Run the following command to watch for a BackupSession:

$ kubectl get backupsession --all-namespaces -w
NAMESPACE   NAME                                       INVOKER-TYPE          INVOKER-NAME    PHASE   DURATION   AGE
demo        sample-backup-frequent-backup-1708413480   BackupConfiguration   sample-backup   Failed             8s

As we can see that the backup has failed this time. Let’s verify the failure notification.

Verify Notification:

If we go to the Slack channel, we should see a new notification has been sent. This time it indicates a failure and also contains the failure reason.

Cleanup

To clean up the test resources we have created throughout this tutorial, run the following commands:

kubectl delete backupconfiguration -n demo sample-backup
kubectl delete backupstorage -n demo gcs-storage
kubectl delete secret -n demo gcs-secret
kubectl delete secret -n demo encrypt-secret
kubectl delete daemonset -n demo ks-demo
kubectl delete hooktemplate -n demo slack-hook

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