Managed MongoDB Service

MongoDB is a popular document-oriented NoSQL database known for its flexibility and scalability. The Managed MongoDB Service provides a self-healing replicated cluster managed by the Percona Operator for MongoDB.

Deployment Details

This managed service is controlled by the Percona Operator for MongoDB, ensuring efficient management and seamless operation.

• Docs: https://docs.percona.com/percona-operator-for-mongodb/
• Github: https://github.com/percona/percona-server-mongodb-operator

Deployment Modes

Replica Set Mode (default)

By default, MongoDB deploys as a replica set with the specified number of replicas. This mode is suitable for most use cases requiring high availability.

Sharded Cluster Mode

Enable sharding: true for horizontal scaling across multiple shards. Each shard is a replica set, and mongos routers handle query routing.

Notes

External Access

When external: true is enabled:

• Replica Set mode: Traffic is load-balanced across all replica set members. This works well for read operations, but write operations require connecting to the primary. MongoDB drivers handle primary discovery automatically using the replica set connection string.
• Sharded mode: Traffic is routed through mongos routers, which handle both reads and writes correctly.

Credentials

On first install, the credentials secret will be empty until the Percona operator initializes the cluster. Run helm upgrade after MongoDB is ready to populate the credentials secret with the actual password.

Data lifecycle

When the MongoDB release is uninstalled, the operator finalizers reclaim release-scoped resources:

Reclaimed by the percona.com/delete-psmdb-pvc finalizer:

• All PVCs backing the replica set storage. Whether the underlying PersistentVolume and on-disk data are actually deleted depends on the StorageClass reclaimPolicy (Delete removes them, Retain leaves them for manual cleanup).
• Operator-managed secrets:
  • <release>-percona-server-mongodb-users — operator users credentials
  • internal-<release> — internal operator state
  • internal-<release>-users — operator-internal users data
  • <release>-mongodb-encryption-key — at-rest encryption key

Reclaimed by helm uninstall:

• <release>-credentials — connection string for application code
• <release>-user-<username> — per-user passwords
• <release>-s3-creds — backup destination credentials (if backups are configured)

Not reclaimed automatically:

• TLS secrets <release>-ssl and <release>-ssl-internal (issued by cert-manager) remain in the namespace after uninstall. Delete them manually if no longer needed.

Recovery from a stuck deletion:

If the psmdb-operator is uninstalled before MongoDB CRs are deleted, the finalizers cannot run and the PerconaServerMongoDB CR hangs in Terminating. To recover, clear the finalizers manually:

kubectl --namespace <namespace> patch psmdb <release> --type merge --patch '{"metadata":{"finalizers":[]}}'

Note that this skips the operator-driven cleanup — PVCs and operator-managed secrets will remain orphaned and must be removed manually.

If you need to retain data, take a backup before deletion. Refer to the Percona Operator for MongoDB documentation for backup/restore workflows.

Upgrading from earlier versions

Earlier versions of this chart referenced a namespace-shared system users secret (percona-server-mongodb-users). Upgrading to a release that scopes this secret per CR (<release>-percona-server-mongodb-users) triggers a password rotation for the operator-managed system users. The rotation is performed in place by the Percona operator via db.changeUserPassword() against the running mongod (operator log: Secret data changed. Updating users...); pods are not restarted and the cluster stays available.

Rotated automatically on upgrade:

• The five operator-managed system accounts: databaseAdmin, userAdmin, backup, clusterAdmin, clusterMonitor.
• Secret <release>-percona-server-mongodb-users (newly created, per-CR) and internal-<release>-users receive the new values.
• Secret <release>-credentials is regenerated; its password and uri keys reflect the new databaseAdmin password.

Not affected:

• Custom users defined under users: in chart values. Their <release>-user-<name> secrets are not touched.
• The at-rest encryption key (<release>-mongodb-encryption-key) and replica set keyfile (<release>-mongodb-keyfile) are unchanged, so on-disk data remains readable.

Action required after upgrade:

Workloads that mount <release>-credentials keep using the cached old password until they re-read the secret. Restart those pods, or run a controller such as Reloader to roll them automatically. Without this, application connections fail with authentication errors once their existing sessions expire.

Orphaned legacy secret:

The previous namespace-shared secret percona-server-mongodb-users is no longer referenced by any MongoDB CR after upgrade, but the operator does not garbage-collect it. If multiple MongoDB releases in the same namespace previously shared it, all of them rotate to their own per-CR secrets — passwords are no longer shared across CRs in the namespace, which is the intended outcome. Confirm no other consumers reference it, then remove it manually:

kubectl --namespace <namespace> delete secret percona-server-mongodb-users

Parameters

Common parameters

Sharding configuration

Users configuration

Databases configuration

Backup parameters

Bootstrap (recovery) parameters