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MongoDB Kubernetes Operator

Available since chart version 3.7.0

The MongoDB Kubernetes Operator is the recommended way to run MongoDB for new Appsmith installations. It replaces the legacy Bitnami MongoDB subchart with an operator-managed replica set backed by the official MongoDB Kubernetes Operator.

Why use the operator​

  • Actively maintained — the Bitnami MongoDB images have been deprecated by their publisher. The operator uses official MongoDB images with ongoing support.
  • Operator-managed lifecycle — a dedicated controller handles replica set membership, SCRAM credential lifecycle, and version upgrades.
  • Automatic connection wiring — the operator creates and maintains the connection-string Secret that Appsmith consumes. No manual URL assembly required.

How the chart integrates the operator​

When mongodbCommunity.enabled: true, the chart:

  • Renders a MongoDBCommunity custom resource that the operator reconciles into a replica set
  • Runs an idempotent pre-install Job that generates a random password and stores it in a Kubernetes Secret (unless you supply your own)
  • Wires the Appsmith workload to read MongoDB's connection string from the operator-managed Secret

When mongodbOperator.enabled: true (recommended), the chart also pulls the upstream mongodb-kubernetes chart as a subchart, installing the operator pod and required CRDs in the same namespace.

Fresh installation​

Prerequisites​

  • Kubernetes 1.28+
  • Helm 3.14+
  • A StorageClass available for MongoDB PVCs (uses the cluster default unless overridden via mongodbCommunity.persistent.storageClass)

Install​

helm repo add appsmith https://helm.appsmith.com
helm repo update

kubectl create namespace appsmith

helm install appsmith appsmith/appsmith -n appsmith --wait --timeout 10m \
  --set mongodb.enabled=false \
  --set mongodbCommunity.enabled=true \
  --set mongodbOperator.enabled=true
FlagPurpose
mongodb.enabled=falseDisables the legacy Bitnami MongoDB subchart
mongodbCommunity.enabled=trueDeploys a MongoDBCommunity CR for the operator to reconcile
mongodbOperator.enabled=trueInstalls the MongoDB Kubernetes Operator in the same namespace

Verify​

kubectl get pods -n appsmith
kubectl get mongodbcommunity -n appsmith

You should see the operator pod, MongoDB pod(s), and the MongoDBCommunity resource in a Running phase.

Access the UI​

kubectl port-forward -n appsmith svc/appsmith 8080:80

Open http://localhost:8080. For production access, configure an Ingress — see Expose Appsmith.

Configuration​

Password management​

When mongodbCommunity.auth.passwordSecretName is empty (the default), the chart's pre-install Job generates a random password. To manage passwords yourself, create a Secret with a password key and reference it:

kubectl create secret generic my-mongodb-secret \
  -n appsmith \
  --from-literal=password='your-password'
mongodbCommunity:
  auth:
    passwordSecretName: my-mongodb-secret

The chart skips the pre-install Job when a Secret name is provided.

To retrieve the auto-generated password:

kubectl get secret appsmith-mongo-password -n appsmith \
  -o jsonpath='{.data.password}' | base64 -d

Production sizing​

The defaults are tuned for evaluation — a single-member replica set with modest storage. For production, scale to three members and pin resources:

mongodbCommunity:
  enabled: true
  members: 3
  persistent:
    storageSize: 100Gi
    storageClass: gp3
  resources:
    requests:
      cpu: 500m
      memory: 2Gi
    limits:
      memory: 4Gi

Scaling from 1 to 3 members after the initial install is a value change on upgrade — the operator handles adding members to the replica set without downtime.

Namespace scope​

Setting mongodbOperator.enabled: true installs the operator in the same namespace as Appsmith. If you manage the operator separately (for example, a cluster-wide install), leave this false and ensure the operator has RBAC access to the release namespace.

Deploying with ArgoCD​

The bundled operator path works with ArgoCD because the CRDs live in the upstream chart's crds/ directory — Helm and ArgoCD install them before any templates are validated.

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: appsmith
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://helm.appsmith.com
    chart: appsmith
    targetRevision: "<chart-version>"
    helm:
      valuesObject:
        mongodb:
          enabled: false
        mongodbCommunity:
          enabled: true
        mongodbOperator:
          enabled: true
  destination:
    server: https://kubernetes.default.svc
    namespace: appsmith
  syncPolicy:
    automated: {}
    syncOptions:
      - CreateNamespace=true

Uninstall​

Delete the MongoDBCommunity resource first so the operator can process its finalizer, then uninstall the release:

# 1. Delete the CR and wait for the operator to clear its finalizer
kubectl delete mongodbcommunity -n appsmith --all --wait=true

# 2. Uninstall Appsmith (and the bundled operator)
helm uninstall appsmith -n appsmith

# 3. Remove the namespace
kubectl delete namespace appsmith
caution

Skipping step 1 can leave the MongoDBCommunity resource stuck with an unresolved finalizer, which blocks namespace deletion. If that happens, clear it manually:

kubectl patch mongodbcommunity -n appsmith <name> \
  --type=merge -p '{"metadata":{"finalizers":[]}}'

The MongoDB CRDs installed by the subchart persist after uninstall (Helm never removes resources from crds/). To fully clean up:

kubectl delete crd mongodbcommunity.mongodbcommunity.mongodb.com
kubectl delete crd mongodb.mongodb.com
kubectl delete crd mongodbusers.mongodb.com
caution

Deleting these CRDs removes all matching resources across the cluster — only do this if nothing else relies on the operator.

Migrate from Bitnami subchart​

If you have an existing Appsmith install using the Bitnami MongoDB subchart, follow this procedure to move to the MongoDB Operator. The migration exports your data from the Bitnami-managed MongoDB and imports it into the operator-managed instance.

caution

Test this procedure on a non-production cluster first. The migration involves a brief downtime window while Appsmith is restarted with the new MongoDB connection.

Overview​

  1. Scale down Appsmith to stop writes
  2. Export data from the Bitnami MongoDB
  3. Deploy the MongoDB Operator alongside the existing release
  4. Import data into the operator-managed MongoDB
  5. Switch Appsmith to the new MongoDB and verify
  6. Clean up the Bitnami MongoDB resources

Step 1: Scale down Appsmith​

Stop the Appsmith workload to prevent writes during the migration:

kubectl scale statefulset appsmith -n appsmith --replicas=0

Wait for all Appsmith pods to terminate before proceeding.

Step 2: Export data from Bitnami MongoDB​

Identify the Bitnami MongoDB pod and run mongodump:

# Find the primary MongoDB pod
kubectl get pods -n appsmith -l app.kubernetes.io/name=mongodb

# Run mongodump inside the pod
kubectl exec -n appsmith appsmith-mongodb-0 -- \
  mongodump --uri="mongodb://root:password@localhost:27017" \
  --archive=/tmp/appsmith-dump.gz --gzip

# Copy the dump to your local machine
kubectl cp appsmith/appsmith-mongodb-0:/tmp/appsmith-dump.gz ./appsmith-dump.gz
tip

If your Bitnami MongoDB uses a non-default root password, retrieve it from the existing Secret:

kubectl get secret appsmith-mongodb -n appsmith \
  -o jsonpath='{.data.mongodb-root-password}' | base64 -d

Step 3: Deploy the MongoDB Operator​

Upgrade the release to enable the MongoDB Operator alongside the existing Bitnami instance. Appsmith remains scaled to zero during this step:

helm upgrade appsmith appsmith/appsmith -n appsmith --wait --timeout 10m \
  --reuse-values \
  --set mongodbCommunity.enabled=true \
  --set mongodbOperator.enabled=true

Wait for the operator-managed MongoDB to reach a Running phase:

kubectl get mongodbcommunity -n appsmith -w

Step 4: Import data into operator-managed MongoDB​

Retrieve the operator-managed MongoDB password:

MONGO_PASS=$(kubectl get secret appsmith-mongo-password -n appsmith \
  -o jsonpath='{.data.password}' | base64 -d)

Copy the dump file into the new MongoDB pod and restore:

# Copy dump to the operator-managed pod
kubectl cp ./appsmith-dump.gz appsmith/appsmith-mongo-0:/tmp/appsmith-dump.gz

# Restore into the new instance
kubectl exec -n appsmith appsmith-mongo-0 -- \
  mongorestore --uri="mongodb://appsmith:${MONGO_PASS}@localhost:27017/appsmith?authSource=appsmith" \
  --archive=/tmp/appsmith-dump.gz --gzip --drop

Step 5: Switch Appsmith to the new MongoDB​

Upgrade the release to disable the Bitnami subchart. Helm will scale Appsmith back to its configured replica count:

helm upgrade appsmith appsmith/appsmith -n appsmith --wait --timeout 10m \
  --reuse-values \
  --set mongodb.enabled=false

Verify Appsmith starts successfully and you can log in with existing credentials. Check the logs for any database connection errors:

kubectl logs -n appsmith appsmith-0 --tail=50

Step 6: Clean up​

Once you've verified the migration is successful, remove the old Bitnami MongoDB PVCs:

# List PVCs from the old Bitnami MongoDB
kubectl get pvc -n appsmith -l app.kubernetes.io/name=mongodb

# Delete them after confirming the new MongoDB is working
kubectl delete pvc -n appsmith -l app.kubernetes.io/name=mongodb

Troubleshooting​

MongoDBCommunity CR stays in Pending phase​

Check the operator logs:

kubectl logs -n appsmith -l app.kubernetes.io/name=mongodb-kubernetes-operator --tail=50

Common causes: the password Secret doesn't exist (if you set passwordSecretName, verify the Secret is present with a password key), or the MongoDB image can't be pulled.

Appsmith pod stuck in Init​

The init container waits for MongoDB to be reachable. Check MongoDB status first (kubectl get mongodbcommunity -n appsmith), then inspect the init container logs:

kubectl logs -n appsmith appsmith-0 -c mongo-init-container

Password init Job fails with ImagePullBackOff​

The cluster can't pull docker.io/alpine/kubectl. Override the image to use your own registry:

mongodbCommunity:
  passwordInit:
    image:
      registry: my-registry.example.com
      repository: my/kubectl
      tag: "1.34.2"

See also​