Deploy the MongoDB Controllers for Kubernetes (MCK) Community Operator

[nickatnceas]

Per a meeting the @mbjones last week we are going to deploy the MongoDB Controllers for Kubernetes (MCK) Community Operator so that we can deploy MongoDB databases when requested (we currently have one person waiting).

Official docs are here: https://github.com/mongodb/mongodb-kubernetes/blob/master/docs/mongodbcommunity/README.md

We need to upgrade K8s based on the requirements page at https://www.mongodb.com/docs/kubernetes/current/tutorial/plan-k8s-op-compatibility/

[nickatnceas]

Installed the operator via the instructions at https://www.mongodb.com/docs/kubernetes/current/tutorial/install-k8s-operator/

outin@bluey:~$ helm repo add mongodb https://mongodb.github.io/helm-charts
"mongodb" has been added to your repositories

outin@bluey:~$ kubectl apply -f https://raw.githubusercontent.com/mongodb/mongodb-kubernetes/1.4.0/public/crds.yaml
customresourcedefinition.apiextensions.k8s.io/clustermongodbroles.mongodb.com created
customresourcedefinition.apiextensions.k8s.io/mongodb.mongodb.com created
customresourcedefinition.apiextensions.k8s.io/mongodbmulticluster.mongodb.com created
customresourcedefinition.apiextensions.k8s.io/mongodbsearch.mongodb.com created
customresourcedefinition.apiextensions.k8s.io/mongodbusers.mongodb.com created
customresourcedefinition.apiextensions.k8s.io/opsmanagers.mongodb.com created
customresourcedefinition.apiextensions.k8s.io/mongodbcommunity.mongodbcommunity.mongodb.com created

outin@bluey:~$ helm upgrade --install mongodb-kubernetes-operator mongodb/mongodb-kubernetes \
> --namespace mongodb \
> --create-namespace
Release "mongodb-kubernetes-operator" does not exist. Installing it now.
NAME: mongodb-kubernetes-operator
LAST DEPLOYED: Mon Oct 13 15:48:03 2025
NAMESPACE: mongodb
STATUS: deployed
REVISION: 1
TEST SUITE: None

outin@bluey:~$ kubectl describe deployments mongodb-kubernetes-operator -n mongodb
Name:                   mongodb-kubernetes-operator
Namespace:              mongodb
CreationTimestamp:      Mon, 13 Oct 2025 15:48:04 -0700
Labels:                 app.kubernetes.io/managed-by=Helm
Annotations:            deployment.kubernetes.io/revision: 1
                        meta.helm.sh/release-name: mongodb-kubernetes-operator
                        meta.helm.sh/release-namespace: mongodb
Selector:               app.kubernetes.io/component=controller,app.kubernetes.io/instance=mongodb-kubernetes-operator,app.kubernetes.io/name=mongodb-kubernetes-operator
Replicas:               1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:           app.kubernetes.io/component=controller
                    app.kubernetes.io/instance=mongodb-kubernetes-operator
                    app.kubernetes.io/name=mongodb-kubernetes-operator
  Service Account:  mongodb-kubernetes-operator
  Containers:
   mongodb-kubernetes-operator:
    Image:      quay.io/mongodb/mongodb-kubernetes:1.4.0
    Port:       <none>
    Host Port:  <none>
    Command:
      /usr/local/bin/mongodb-kubernetes-operator
    Args:
      -watch-resource=mongodb
      -watch-resource=opsmanagers
      -watch-resource=mongodbusers
      -watch-resource=mongodbcommunity
      -watch-resource=mongodbsearch
      -watch-resource=clustermongodbroles
    Limits:
      cpu:     1100m
      memory:  1Gi
    Requests:
      cpu:     500m
      memory:  200Mi
    Environment:
      OPERATOR_ENV:                                 prod
      MDB_DEFAULT_ARCHITECTURE:                     non-static
      NAMESPACE:                                     (v1:metadata.namespace)
      WATCH_NAMESPACE:                               (v1:metadata.namespace)
      MDB_OPERATOR_TELEMETRY_COLLECTION_FREQUENCY:  1h
      MDB_OPERATOR_TELEMETRY_SEND_FREQUENCY:        168h
      CLUSTER_CLIENT_TIMEOUT:                       10
      IMAGE_PULL_POLICY:                            Always
      MONGODB_ENTERPRISE_DATABASE_IMAGE:            quay.io/mongodb/mongodb-kubernetes-database
      INIT_DATABASE_IMAGE_REPOSITORY:               quay.io/mongodb/mongodb-kubernetes-init-database
      INIT_DATABASE_VERSION:                        1.4.0
      DATABASE_VERSION:                             1.4.0
      OPS_MANAGER_IMAGE_REPOSITORY:                 quay.io/mongodb/mongodb-enterprise-ops-manager-ubi
      INIT_OPS_MANAGER_IMAGE_REPOSITORY:            quay.io/mongodb/mongodb-kubernetes-init-ops-manager
      INIT_OPS_MANAGER_VERSION:                     1.4.0
      INIT_APPDB_IMAGE_REPOSITORY:                  quay.io/mongodb/mongodb-kubernetes-init-appdb
      INIT_APPDB_VERSION:                           1.4.0
      OPS_MANAGER_IMAGE_PULL_POLICY:                Always
      AGENT_IMAGE:                                  quay.io/mongodb/mongodb-agent:108.0.12.8846-1
      MDB_AGENT_IMAGE_REPOSITORY:                   quay.io/mongodb/mongodb-agent
      MONGODB_IMAGE:                                mongodb-enterprise-server
      MONGODB_REPO_URL:                             quay.io/mongodb
      MDB_IMAGE_TYPE:                               ubi8
      PERFORM_FAILOVER:                             true
      MDB_MAX_CONCURRENT_RECONCILES:                1
      POD_NAME:                                      (v1:metadata.name)
      OPERATOR_NAME:                                mongodb-kubernetes-operator
      MDB_COMMUNITY_AGENT_IMAGE:                    quay.io/mongodb/mongodb-agent:108.0.2.8729-1
      VERSION_UPGRADE_HOOK_IMAGE:                   quay.io/mongodb/mongodb-kubernetes-operator-version-upgrade-post-start-hook:1.0.9
      READINESS_PROBE_IMAGE:                        quay.io/mongodb/mongodb-kubernetes-readinessprobe:1.0.22
      MDB_COMMUNITY_IMAGE:                          mongodb-community-server
      MDB_COMMUNITY_REPO_URL:                       quay.io/mongodb
      MDB_COMMUNITY_IMAGE_TYPE:                     ubi8
      MDB_SEARCH_REPO_URL:                          quay.io/mongodb
      MDB_SEARCH_NAME:                              mongodb-search
      MDB_SEARCH_VERSION:                           0.53.1
    Mounts:                                         <none>
  Volumes:                                          <none>
  Node-Selectors:                                   <none>
  Tolerations:                                      <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   mongodb-kubernetes-operator-56497dbbc9 (1/1 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  2m10s  deployment-controller  Scaled up replica set mongodb-kubernetes-operator-56497dbbc9 to 1

[nickatnceas]

Attempts to spin up a database have not yet been successful. I'm at the point where a pod is created, but it ends up in a restart loop.

The crashing pod also prevents backups of k8s-dev from completing.

---
apiVersion: mongodbcommunity.mongodb.com/v1
kind: MongoDBCommunity
metadata:
  name: test-mongodb
  namespace: mongodb
spec:
  members: 1
  type: ReplicaSet
  version: "6.0.13"
  security:
    authentication:
      modes: ["SCRAM"]
  users:
    - name: my-user
      db: admin
      passwordSecretRef: # a reference to the secret that will be used to generate the user's password
        name: my-user-password
      roles:
        - name: clusterAdmin
          db: admin
        - name: userAdminAnyDatabase
          db: admin
      scramCredentialsSecretName: my-scram
  additionalMongodConfig:
    storage.wiredTiger.engineConfig.journalCompressor: zlib
  statefulSet:
    spec:
      volumeClaimTemplates:
        - metadata:
            name: data-volume
          spec:
            accessModes: [ "ReadWriteOnce" ]
            resources:
              requests:
                storage: 10Gi
            storageClassName: csi-cephfs-sc-ephemeral
        - metadata:
            name: logs-volume
          spec:
            accessModes: [ "ReadWriteOnce" ]
            resources:
              requests:
                storage: 5Gi
            storageClassName: csi-cephfs-sc-ephemeral

[nickatnceas]

Currently using the docs and issue at:

• https://github.com/mongodb/mongodb-kubernetes/blob/master/docs/mongodbcommunity/deploy-configure.md
• How to specify the storage-class of the data pvc? mongodb/mongodb-kubernetes#290

[mbjones]

@nickatnceas I tried to spin this up too in my jones namespace but it looks like the operator was not installed cluster-wide, so it only watches the mongodb namespace. I don't want to try it there for fear of messing up backups. Can you post the errors you see with:

1. kubectl -n mongodb describe mongodbcommunity mongo-test
2. kubectl -n mongodb get pods
3. kubectl -n mongodb logs mongodbcommunity/mongo-test
4. kubectl -n mongodb logs mongodb-kubernetes-operator-56497dbbc9-cpb8s for the period when the mongodb instance is starting

Often those failures to spin up are a simple config issue with creating or matching volumes, secrets, configs or some other needed resource.