mongodb

MongoDB

MongoDB is a cross-platform document-oriented database. Classified as a NoSQL database, MongoDB eschews the traditional table-based relational database structure in favor of JSON-like documents with dynamic schemas, making the integration of data in certain types of applications easier and faster.

Prerequisites

• Kubernetes 1.20+
• Kubernetes beta APIs enabled only if podDisruptionBudget is enabled
• PV support on the underlying infrastructure
• Kanister controller version 0.85.0 installed in your cluster
• Kanctl CLI installed (https://docs.kanister.io/tooling.html#install-the-tools)

Chart Details

We will be using bitnami mongodb chart from official helm repo which bootstraps a MongoDB deployment on a Kubernetes cluster in replication mode using the Helm package manager.

Installing the Chart

To install the chart with the release name my-release:

$ helm repo add bitnami https://charts.bitnami.com/bitnami
$ helm repo update

$ helm install my-release bitnami/mongodb --namespace mongo-test --create-namespace \
	--set architecture="replicaset"

The command deploys MongoDB on the Kubernetes cluster in the mongo-test namespace

Integrating with Kanister

If you have deployed mongodb application with other name than my-release and namespace other than mongo-test, you need to modify the commands used below to use the correct name and namespace

Create Profile

Create Profile CR if not created already

$ kanctl create profile s3compliant --access-key <aws-access-key-id> \
	--secret-key <aws-secret-key> \
	--bucket <s3-bucket-name> --region <region-name> \
	--namespace mongo-test

NOTE:

The command will configure a location where artifacts resulting from Kanister data operations such as backup should go. This is stored as a profiles.cr.kanister.io CustomResource (CR) which is then referenced in Kanister ActionSets. Every ActionSet requires a Profile reference to complete the action. This CR (profiles.cr.kanister.io) can be shared between Kanister-enabled application instances.

NOTE:

If you have installed MongoDB chart using existing mongo secret by setting paramter --set auth.existingSecret=<mongo-secret-name> you will need to modify the secret name in the blueprint mongo-blueprint.yaml at following places:

actions.backup.phases[0].objects.mongosecret.name: <mongo-secret-name>
actions.restore.phases[0].objects.mongosecret.name: <mongo-secret-name>

Create Blueprint

Create Blueprint in the same namespace as the controller

$ kubectl create -f ./mongo-blueprint.yaml -n kanister

Once MongoDB is running, you can populate it with some data. Let's add a collection called "restaurants" to a test database:

# Connect to MongoDB primary pod
$ kubectl exec -ti my-release-mongodb-0 -n mongo-test -- bash

# From inside the shell, use the mongo CLI to insert some data into the test database
$ mongosh admin --authenticationDatabase admin -u root -p $MONGODB_ROOT_PASSWORD --quiet --eval "db.restaurants.insertOne({'name' : 'Roys', 'cuisine' : 'Hawaiian', 'id' : '8675309'})"
{
  acknowledged: true,
  insertedId: ObjectId("6393065091e5c8cd94289f16")
}

# View the restaurants data in the test database
$ mongosh admin --authenticationDatabase admin -u root -p $MONGODB_ROOT_PASSWORD --quiet --eval "db.restaurants.find()"
[
  {
    _id: ObjectId("6393059b7844b3c1445e9d14"),
    name: 'Roys',
    cuisine: 'Hawaiian',
    id: '8675309'
  }
]

Protect the Application

You can now take a backup of the MongoDB data using an ActionSet defining backup for this application. Create an ActionSet in the same namespace as the controller.

$ kubectl get profile -n mongo-test
NAME               AGE
s3-profile-sph7s   2h

$ kanctl create actionset --action backup --namespace kanister --blueprint mongodb-blueprint --statefulset mongo-test/my-release-mongodb --profile mongo-test/s3-profile-sph7s
actionset backup-llfb8 created

# View the status of the actionset
$ kubectl --namespace kanister get actionsets.cr.kanister.io
NAME           PROGRESS   LAST TRANSITION TIME   STATE
backup-thkll   100.00     2022-12-09T10:01:42Z   complete

Disaster strikes!

Let's say someone with fat fingers accidentally deleted the restaurants collection using the following command in mongodb primary pod:

# Connect to MongoDB primary pod
$ kubectl exec -ti my-release-mongodb-0 -n mongo-test -- bash

# Drop the restaurants collection
$ mongosh admin --authenticationDatabase admin -u root -p $MONGODB_ROOT_PASSWORD --quiet --eval "db.restaurants.drop()"
true

If you try to access this data in the database, you should see that it is no longer there:

$ mongosh admin --authenticationDatabase admin -u root -p $MONGODB_ROOT_PASSWORD --quiet --eval "db.restaurants.find()"
# No entries should be found in the restaurants collection

Restore the Application

To restore the missing data, you should use the backup that you created before. An easy way to do this is to leverage kanctl, a command-line tool that helps create ActionSets that depend on other ActionSets:

NOTE:

As a part of restore operation in MongoDB ReplicaSet, we are deleting data from the Secondary replicas to allow MongoDB to use Initial Sync for updating Secondaries as documented here

$ kanctl --namespace kanister create actionset --action restore --from "backup-llfb8"
actionset restore-backup-llfb8-64gqm created

# View the status of the ActionSet
kubectl --namespace kanister get actionset restore-backup-llfb8-64gqm
NAME                         PROGRESS   LAST TRANSITION TIME   STATE
restore-backup-llfb8-64gqm   100.00     2022-12-09T10:06:39Z   complete

You should now see that the data has been successfully restored to MongoDB!

# Connect to MongoDB primary pod
$ kubectl exec -ti my-release-mongodb-0 -n mongo-test -- bash

$ mongosh admin --authenticationDatabase admin -u root -p $MONGODB_ROOT_PASSWORD --quiet --eval "db.restaurants.find()"
[
  {
    _id: ObjectId("6393059b7844b3c1445e9d14"),
    name: 'Roys',
    cuisine: 'Hawaiian',
    id: '8675309'
  }
]

Delete the Artifacts

The artifacts created by the backup action can be cleaned up using the following command:

$ kanctl --namespace kanister create actionset --action delete --from "backup-llfb8" --namespacetargets kanister
actionset "delete-backup-llfb8-k9ncm" created

# View the status of the ActionSet
$ kubectl --namespace kanister get actionset delete-backup-llfb8-k9ncm
NAME                         PROGRESS   LAST TRANSITION TIME   STATE
delete-backup-llfb8-k9ncm    100.00     2022-12-09T10:08:20Z   complete

Troubleshooting

If you run into any issues with the above commands, you can check the logs of the controller using:

$ kubectl --namespace kanister logs -l app=kanister-operator

you can also check events of the actionset

$ kubectl describe actionset restore-backup-llfb8-64gqm -n kanister

Uninstalling the Chart

To uninstall/delete the my-release deployment:

$ helm delete my-release -n mongo-test

The command removes all the Kubernetes components associated with the chart and deletes the release. To completely remove the release include the --purge flag.

Delete Blueprint, Profile CR and ActionSet

$ kubectl delete blueprints.cr.kanister.io mongodb-blueprint -n kanister

$ kubectl get profiles.cr.kanister.io -n mongo-test
NAME               AGE
s3-profile-sph7s   2h

$ kubectl delete profiles.cr.kanister.io s3-profile-sph7s -n mongo-test

$ kubectl delete actionset backup-llfb8 restore-backup-llfb8-64gqm delete-backup-llfb8-k9ncm -n kanister