Backup Helm managed NATS using Stash

Stash v2023.04.30 supports backup and restoration of NATS streams. This guide will show you how you can backup & restore a Helm managed NATS server using Stash.

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.
• Install Stash Enterprise in your cluster following the steps here.
• If you are not familiar with how Stash backup and restore NATS streams, please check the following guide here.

You have to be familiar with following custom resources:

• AppBinding
• Function
• Task
• BackupConfiguration
• BackupSession
• RestoreSession

To keep things isolated, we are going to use a separate namespace called demo throughout this tutorial. Create demo namespace if you haven’t created already.

$ kubectl create ns demo
namespace/demo created

Note: YAML files used in this tutorial are stored here.

Prepare NATS

In this section, we are going to deploy a NATS cluster. Then, we are going to insert some sample data into it.

Deploy NATS Cluster

At first, let’s deploy a NATS cluster. Here, we are going to use NATS chart from nats.io.

Let’s deploy a nats cluster named sample-nats using Helm as below,

# Add nats chart registry
$ helm repo add nats https://nats-io.github.io/k8s/helm/charts/ 
# Update helm registries
$ helm repo update
# Install nats/nats chart into demo namespace
$ helm install sample-nats nats/nats -n demo \
--set nats.jetstream.enabled=true \
--set nats.jetstream.fileStorage.enabled=true \
--set cluster.enabled=true \
--set cluster.replicas=3 

This chart will create the necessary StatefulSet, Service, PVCs etc. for the NATS cluster. You can easily view all the resources created by chart using ketall kubectl plugin as below,

❯ kubectl get-all -n demo -l app.kubernetes.io/instance=sample-nats
NAME                                                    NAMESPACE  AGE
configmap/sample-nats-config                            demo       11m  
endpoints/sample-nats                                   demo       11m  
persistentvolumeclaim/sample-nats-js-pvc-sample-nats-0  demo       11m  
persistentvolumeclaim/sample-nats-js-pvc-sample-nats-1  demo       10m  
persistentvolumeclaim/sample-nats-js-pvc-sample-nats-2  demo       10m  
pod/sample-nats-0                                       demo       11m  
pod/sample-nats-1                                       demo       10m  
pod/sample-nats-2                                       demo       10m  
service/sample-nats                                     demo       11m  
controllerrevision.apps/sample-nats-775468b94f          demo       11m  
statefulset.apps/sample-nats                            demo       11m  
endpointslice.discovery.k8s.io/sample-nats-7n7v6        demo       11m  

Now, wait for the NATS server pods sample-nats-0, sample-nats-1, sample-nats-2 to go into Running state,

❯ kubectl get pod -n demo -l app.kubernetes.io/instance=sample-nats
NAME            READY   STATUS    RESTARTS   AGE
sample-nats-0   3/3     Running   0          9m58s
sample-nats-1   3/3     Running   0          9m35s
sample-nats-2   3/3     Running   0          9m12s

Once the nats server pods are in Running state, verify that the NATS server is ready to accept the connections.

❯ kubectl logs -n demo sample-nats-0 -c nats
[7] 2021/09/06 08:33:53.111508 [INF] Starting nats-server
[7] 2021/09/06 08:33:53.111560 [INF] Version:  2.6.1
...
[7] 2021/09/06 08:33:53.116004 [INF] Server is ready

From the above log, we can see the NATS server is ready to accept connections.

Insert Sample Data

The above Helm chart also deploy a pod with nats-box image which can be used to interact with the NATS server. Let’s verify the nats-box pod has been created.

❯ kubectl get pod -n demo -l app=sample-nats-box
NAME                               READY   STATUS    RESTARTS   AGE
sample-nats-box-785f8458d7-wtnfx   1/1     Running   0          7m20s

Now, let’s exec into the nats-box pod and insert some sample data,

❯ kubectl exec -n demo -it sample-nats-box-785f8458d7-wtnfx -- sh -l
...
# Let's create a stream named "ORDERS"
sample-nats-box-785f8458d7-wtnfx:~# nats stream add ORDERS --subjects "ORDERS.*" --ack --max-msgs=-1 --max-bytes=-1 --max-age=1y --storage file --retention limits --max-msg-size=-1 --max-msgs-per-subject=-1 --discard old --dupe-window="0s" --replicas 1
Stream ORDERS was created

Information for Stream ORDERS created 2021-09-03T07:12:07Z

Configuration:

             Subjects: ORDERS.*
     Acknowledgements: true
            Retention: File - Limits
             Replicas: 1
       Discard Policy: Old
     Duplicate Window: 2m0s
     Maximum Messages: unlimited
        Maximum Bytes: unlimited
          Maximum Age: 1y0d0h0m0s
 Maximum Message Size: unlimited
    Maximum Consumers: unlimited


Cluster Information:

                 Name: nats
               Leader: nats-0

State:

             Messages: 0
                Bytes: 0 B
             FirstSeq: 0
              LastSeq: 0
     Active Consumers: 0


# Verify that the stream has been created successfully
sample-nats-box-785f8458d7-wtnfx:~#  nats stream ls
Streams:

	ORDERS
	
# Lets add some messages to the stream "ORDERS"
sample-nats-box-785f8458d7-wtnfx:~# nats pub ORDERS.scratch hello
08:55:39 Published 5 bytes to "ORDERS.scratch"

# Add another message
sample-nats-box-785f8458d7-wtnfx:~# nats pub ORDERS.scratch world
08:56:11 Published 5 bytes to "ORDERS.scratch"

# Verify that the messages have been published to the stream successfully
sample-nats-box-785f8458d7-wtnfx:~# nats stream info ORDERS
Information for Stream ORDERS created 2021-09-03T07:12:07Z

Configuration:

             Subjects: ORDERS.*
     Acknowledgements: true
            Retention: File - Limits
             Replicas: 1
       Discard Policy: Old
     Duplicate Window: 2m0s
     Maximum Messages: unlimited
        Maximum Bytes: unlimited
          Maximum Age: 1y0d0h0m0s
 Maximum Message Size: unlimited
    Maximum Consumers: unlimited


Cluster Information:

                 Name: nats
               Leader: nats-0

State:

             Messages: 2
                Bytes: 98 B
             FirstSeq: 1 @ 2021-09-03T08:55:39 UTC
              LastSeq: 2 @ 2021-09-03T08:56:11 UTC
     Active Consumers: 0

sample-nats-box-785f8458d7-wtnfx:~# exit

We have successfully deployed a NATS cluster, created a stream and publish some messages into the stream. In the subsequent sections, we are going to backup this sample data using Stash.

Prepare for Backup

In this section, we are going to prepare the necessary resources (i.e. connection information, backend information, etc.) before backup.

Ensure NATS Addon

When you install Stash Enterprise version, it will automatically install all the official addons. Make sure that NATS addon has been installed properly using the following command.

❯ kubectl get tasks.stash.appscode.com | grep nats
nats-backup-2.6.1            24m
nats-restore-2.6.1           24m

This addon should be able to take backup of the NATS streams with matching major versions as discussed in Addon Version Compatibility.

Create AppBinding

Stash needs to know how to connect with the NATS server. An AppBinding exactly provides this information. It holds the Service and Secret information of the NATS server. You have to point to the respective AppBinding as a target of backup instead of the NATS server itself.

Here, is the YAML of the AppBinding that we are going to create for the NATS server we have deployed earlier.

apiVersion: appcatalog.appscode.com/v1alpha1
kind: AppBinding
metadata:
  labels:
    app.kubernetes.io/instance: sample-nats
  name: sample-nats
  namespace: demo
spec:
  clientConfig:
    service:
      name: sample-nats
      port: 4222
      scheme: nats
  type: nats.io/nats
  version: 2.6.1

Here,

• .spec.clientConfig.service specifies the Service information to use to connects with the NATS server.
• spec.type specifies the type of the target. This is particularly helpful in auto-backup where you want to use different path prefixes for different types of target.

Let’s create the AppBinding we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/tree/v2023.04.30/docs/addons/nats/helm/examples/appbinding.yaml
appbinding.appcatalog.appscode.com/sample-nats created

Prepare Backend

We are going to store our backed up data into a GCS bucket. So, we need to create a Secret with GCS credentials and a Repository object with the bucket information. If you want to use a different backend, please read the respective backend configuration doc from here.

Create Storage Secret:

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

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

Create Repository:

Now, create a Repository object with the information of your desired bucket. Below is the YAML of Repository object we are going to create,

apiVersion: stash.appscode.com/v1alpha1
kind: Repository
metadata:
  name: gcs-repo
  namespace: demo
spec:
  backend:
    gcs:
      bucket: stash-testing
      prefix: /demo/nats/sample-nats
    storageSecretName: gcs-secret

Let’s create the Repository we have shown above,

$ kubectl create -f https://github.com/stashed/docs/raw/v2023.04.30/docs/addons/nats/helm/examples/repository.yaml
repository.stash.appscode.com/gcs-repo created

Now, we are ready to backup our streams into our desired backend.

Backup

To schedule a backup, we have to create a BackupConfiguration object targeting the respective AppBinding of our NATS server. Then, Stash will create a CronJob to periodically backup the streams.

Create BackupConfiguration

Below is the YAML for BackupConfiguration object that we are going to use to backup the streams of the NATS server we have created earlier,

apiVersion: stash.appscode.com/v1beta1
kind: BackupConfiguration
metadata:
  name: sample-nats-backup
  namespace: demo
spec:
  task:
    name: nats-backup-2.6.1
  schedule: "*/5 * * * *"
  repository:
    name: gcs-repo
  target:
    ref:
      apiVersion: appcatalog.appscode.com/v1alpha1
      kind: AppBinding
      name: sample-nats
  interimVolumeTemplate:
    metadata:
      name: sample-nats-backup-tmp-storage
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "standard"
      resources:
        requests:
          storage: 1Gi  
  retentionPolicy:
    name: keep-last-5
    keepLast: 5
    prune: true

Here,

• .spec.schedule specifies that we want to backup the streams at 5 minutes intervals.
• .spec.task.name specifies the name of the Task object that specifies the necessary Functions and their execution order to backup NATS streams.
• .spec.repository.name specifies the Repository CR name we have created earlier with backend information.
• .spec.target.ref refers to the AppBinding object that holds the connection information of our targeted NATS server.
• spec.interimVolumeTemplate specifies a PVC template that will be used by Stash to hold the dumped data temporarily before uploading it into the cloud bucket.
• .spec.retentionPolicy specifies a policy indicating how we want to cleanup the old backups.

Let’s create the BackupConfiguration object we have shown above,

$ kubectl create -f https://github.com/stashed/docs/raw/v2023.04.30/docs/addons/nats/helm/examples/backupconfiguration.yaml
backupconfiguration.stash.appscode.com/sample-nats-backup created

Verify Backup Setup Successful

If everything goes well, the phase of the BackupConfiguration should be Ready. The Ready phase indicates that the backup setup is successful. Let’s verify the Phase of the BackupConfiguration,

$ kubectl get backupconfiguration -n demo
NAME                    TASK                    SCHEDULE      PAUSED   PHASE      AGE
sample-nats-backup      nats-backup-2.6.1       */5 * * * *            Ready      11s

Verify CronJob

Stash will create a CronJob with the schedule specified in spec.schedule field of BackupConfiguration object.

Verify that the CronJob has been created using the following command,

❯ kubectl get cronjob -n demo
NAME                               SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
stash-backup-sample-nats-backup    */5 * * * *   False     0        <none>          14s

Wait for BackupSession

The sample-nats-backup CronJob will trigger a backup on each scheduled slot by creating a BackupSession object.

Now, wait for a schedule to appear. Run the following command to watch for BackupSession object,

❯ kubectl get backupsession -n demo -w
NAME                       INVOKER-TYPE          INVOKER-NAME         PHASE       DURATION   AGE
sample-nats-backup-8x8fp   BackupConfiguration   sample-nats-backup   Succeeded   42s        8m28s

Here, the phase Succeeded means that the backup process has been completed successfully.

Verify Backup

Now, we are going to verify whether the backed up data is present in the backend or not. Once a backup is completed, Stash will update the respective Repository object to reflect the backup completion. Check that the repository gcs-repo has been updated by the following command,

❯ kubectl get repository -n demo
NAME       INTEGRITY   SIZE        SNAPSHOT-COUNT   LAST-SUCCESSFUL-BACKUP   AGE
gcs-repo   true        1.382 KiB   1                9m4s                     24m

Now, if we navigate to the GCS bucket, we will see the backed up data has been stored in demo/nats/sample-nats directory as specified by .spec.backend.gcs.prefix field of the Repository object.

Note: Stash keeps all the backed up data encrypted. So, data in the backend will not make any sense until they are decrypted.

Restore

If you have followed the previous sections properly, you should have a successful backup of your NATS streams. Now, we are going to show how you can restore the streams from the backed up data.

Restore Into the Same NATS Cluster

You can restore your data into the same NATS cluster you have backed up from or into a different NATS cluster in the same cluster or a different cluster. In this section, we are going to show you how to restore in the same NATS cluster which may be necessary when you have accidentally lost any data.

Temporarily Pause Backup

At first, let’s stop taking any further backup of the NATS streams so that no backup runs after we delete the sample data. We are going to pause the BackupConfiguration object. Stash will stop taking any further backup when the BackupConfiguration is paused.

Let’s pause the sample-nats-backup BackupConfiguration,

$ kubectl patch backupconfiguration -n demo sample-nats-backup --type="merge" --patch='{"spec": {"paused": true}}'
backupconfiguration.stash.appscode.com/sample-nats-backup patched

Verify that the BackupConfiguration has been paused,

❯ kubectl get backupconfiguration -n demo sample-nats-backup
NAME                 TASK                SCHEDULE      PAUSED   PHASE   AGE
sample-nats-backup   nats-backup-2.6.1   */5 * * * *   true     Ready   2d18h

Notice the PAUSED column. Value true for this field means that the BackupConfiguration has been paused.

Stash will also suspend the respective CronJob.

❯ kubectl get cronjob -n demo
NAME                              SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
stash-backup-sample-nats-backup   */5 * * * *   True      0        56s             2d18h

Simulate Disaster

Now, let’s simulate a disaster scenario. Here, we are going to exec into the nats-box pod and delete the sample data we have inserted earlier.

❯ kubectl exec -n demo -it sample-nats-box-785f8458d7-wtnfx -- sh -l
...
# delete the stream "ORDERS"
sample-nats-box-785f8458d7-wtnfx:~# nats stream rm ORDERS -f

# verify that the stream has been deleted
sample-nats-box-785f8458d7-wtnfx:~# nats stream ls
No Streams defined

sample-nats-box-785f8458d7-wtnfx:~# exit

Create RestoreSession

To restore the streams, you have to create a RestoreSession object pointing to the AppBinding of the targeted NATS server.

Here, is the YAML of the RestoreSession object that we are going to use for restoring the streams of the NATS server.

apiVersion: stash.appscode.com/v1beta1
kind: RestoreSession
metadata:
  name: sample-nats-restore
  namespace: demo
spec:
  task:
    name: nats-restore-2.6.1
  repository:
    name: gcs-repo
  target:
    ref:
      apiVersion: appcatalog.appscode.com/v1alpha1
      kind: AppBinding
      name: sample-nats
  interimVolumeTemplate:
    metadata:
      name: nats-restore-tmp-storage
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "standard"
      resources:
        requests:
          storage: 1Gi
  rules:
  - snapshots: [latest]

Here,

• .spec.task.name specifies the name of the Task object that specifies the necessary Functions and their execution order to restore NATS streams.
• .spec.repository.name specifies the Repository object that holds the backend information where our backed up data has been stored.
• .spec.target.ref refers to the respective AppBinding of the sample-nats cluster.
• .spec.interimVolumeTemplate specifies a PVC template that will be used by Stash to hold the restored data temporarily before injecting into the NATS server.
• .spec.rules specifies that we are restoring data from the latest backup snapshot of the streams.

Let’s create the RestoreSession object object we have shown above,

$ kubectl apply -f https://github.com/stashed/docs/raw/v2023.04.30/docs/addons/nats/helm/examples/restoresession.yaml
restoresession.stash.appscode.com/sample-nats-restore created

Once, you have created the RestoreSession object, Stash will create a restore Job. Run the following command to watch the phase of the RestoreSession object,

❯ kubectl get restoresession -n demo -w
NAME                  REPOSITORY   PHASE       DURATION   AGE
sample-nats-restore   gcs-repo     Succeeded   15s        55s

The Succeeded phase means that the restore process has been completed successfully.

Verify Restored Data

Now, let’s exec into the nats-box pod and verify whether data actual data has been restored or not,

❯ kubectl exec -n demo -it sample-nats-box-785f8458d7-wtnfx -- sh -l
...
# Verify that the stream has been restored successfully
sample-nats-box-785f8458d7-wtnfx:~#  nats stream ls
Streams:

	ORDERS

# Verify that the messages have been restored successfully
sample-nats-box-785f8458d7-wtnfx:~# nats stream info ORDERS
Information for Stream ORDERS created 2021-09-03T07:12:07Z

Configuration:

             Subjects: ORDERS.*
     Acknowledgements: true
            Retention: File - Limits
             Replicas: 1
       Discard Policy: Old
     Duplicate Window: 2m0s
     Maximum Messages: unlimited
        Maximum Bytes: unlimited
          Maximum Age: 1y0d0h0m0s
 Maximum Message Size: unlimited
    Maximum Consumers: unlimited


Cluster Information:

                 Name: nats
               Leader: nats-0

State:

             Messages: 2
                Bytes: 98 B
             FirstSeq: 1 @ 2021-09-03T08:55:39 UTC
              LastSeq: 2 @ 2021-09-03T08:56:11 UTC
     Active Consumers: 0

sample-nats-box-785f8458d7-wtnfx:~# exit

Hence, we can see from the above output that the deleted data has been restored successfully from the backup.

Resume Backup

Since our data has been restored successfully we can now resume our usual backup process. Resume the BackupConfiguration using following command,

❯ kubectl patch backupconfiguration -n demo sample-nats-backup --type="merge" --patch='{"spec": {"paused": false}}'
backupconfiguration.stash.appscode.com/sample-nats-backup patched

Verify that the BackupConfiguration has been resumed,

❯ kubectl get backupconfiguration -n demo sample-nats-backup
NAME                 TASK                SCHEDULE      PAUSED   PHASE   AGE
sample-nats-backup   nats-backup-2.6.1   */5 * * * *   false    Ready   2d19h

Here, false in the PAUSED column means the backup has been resumed successfully. The CronJob also should be resumed now.

❯ kubectl get cronjob -n demo
NAME                               SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
stash-backup-sample-nats-backup    */5 * * * *   False     0        3m24s           4h54m

Here, False in the SUSPEND column means the CronJob is no longer suspended and will trigger in the next schedule.

Restore Into Different NATS Cluster of the Same Namespace

If you want to restore the backed up data into a different NATS cluster of the same namespace, you have to create another AppBinding pointing to the desired NATS cluster. Then, you have to create the RestoreSession pointing to the new AppBinding.

Restore Into Different Namespace

If you want to restore into a different namespace of the same cluster, you have to create the Repository, backend Secret, AppBinding, in the desired namespace. You can use Stash kubectl plugin to easily copy the resources into a new namespace. Then, you have to create the RestoreSession object in the desired namespace pointing to the Repository, AppBinding of that namespace.

Restore Into Different Cluster

If you want to restore into a different cluster, you have to install Stash in the desired cluster. Then, you have to create the Repository, backend Secret, AppBinding, in the desired cluster. Finally, you have to create the RestoreSession object in the desired cluster pointing to the Repository, AppBinding of that cluster.

Cleanup

To cleanup the Kubernetes resources created by this tutorial, run:

kubectl delete -n demo backupconfiguration sample-nats-backup
kubectl delete -n demo restoresession sample-nats-restore
kubectl delete -n demo repository gcs-repo
# delete the nats chart
helm delete sample-nats -n demo