Multi-Kubernetes-Cluster Quick Start¶

Create the secret for the TLS certificate of your MongoDBMultiCluster resource.¶

Run the kubectl command to create a new secret that stores the MongoDBMultiCluster resource certificate:

kubectl --context $MDB_CENTRAL_CLUSTER_FULL_NAME \
  --namespace=<metadata.namespace> \
  create secret tls <prefix>-<metadata.name>-cert \
  --cert=<resource-tls-cert> \
  --key=<resource-tls-key>

Create the ConfigMap to link your CA with your MongoDBMultiCluster resource.¶

Run the kubectl command to link your CA to your MongoDBMultiCluster resource:

kubectl --context $MDB_CENTRAL_CLUSTER_FULL_NAME \
  --namespace=<metadata.namespace> \
  create configmap custom-ca -from-file=ca-pem

Run the kubectl mongodb plugin.¶

By default, the Kubernetes Operator is scoped to the mongodb namespace. When you run the following command, the kubectl mongodb plugin:

• Creates one central cluster, three member clusters, and a namespace labeled mongodb in each of the clusters.
• Creates a default ConfigMap with the hard-coded name mongodb-enterprise-operator-member-list that contains all the member clusters. You can’t change the ConfigMap’s name.
• Creates the service accounts and Roles required for running database workloads in the member clusters.

Run the kubectl mongodb plugin:

kubectl mongodb multicluster setup \
  --central-cluster="${MDB_CENTRAL_CLUSTER_FULL_NAME}" \
  --member-clusters="${MDB_CLUSTER_1_FULL_NAME},${MDB_CLUSTER_2_FULL_NAME},${MDB_CLUSTER_3_FULL_NAME}" \
  --member-cluster-namespace="mongodb" \
  --central-cluster-namespace="mongodb" \
  --create-service-account-secrets \
  --install-database-roles=true

Optional: Set the Istio injection webhook in each member cluster.¶

If you’re using Istio, run the following command on the central cluster, specifying the context for each of the member clusters in the deployment. These commands add the istio-injection=enabled label to the mongodb namespace on each member cluster. This label configures Istio’s injection webhook which enables adding a sidecar to any Pods that you create in this namespace. To learn more, see Automatic sidecar injection in the Istio documentation.

kubectl label \
  --context=$MDB_CLUSTER_1_FULL_NAME \
  namespace mongodb \
  istio-injection=enabled

kubectl label \
  --context=$MDB_CLUSTER_2_FULL_NAME \
  namespace mongodb \
  istio-injection=enabled

kubectl label \
  --context=$MDB_CLUSTER_3_FULL_NAME \
  namespace mongodb \
  istio-injection=enabled

Configure kubectl to use the central cluster’s namespace.¶

If you have not done so already, run the following commands to run all kubectl commands on the central cluster in the default namespace.

kubectl config use-context $MDB_CENTRAL_CLUSTER_FULL_NAME
kubectl config set-context $(kubectl config current-context) \
  --namespace=mongodb

Deploy the MongoDB Enterprise Kubernetes Operator in the central cluster.¶

Deploy the MongoDB Enterprise Kubernetes Operator in the central cluster in the mongodb namespace with Helm or kubectl.

Create a secret to use with Ops Manager and create a ConfigMap.¶

1. Create a secret so that the Kubernetes Operator can create and update objects in your Ops Manager project. To learn more, see Create Credentials for the Kubernetes Operator.
2. Create a ConfigMap to link the Kubernetes Operator to your Ops Manager project. To learn more, see Create One Project using a ConfigMap.

Deploy Ops Manager on the central cluster and connect to Ops Manager.¶

Review the multi-Kubernetes-cluster deployment exceptions and follow the linked procedures in Deploy an Ops Manager Resource on the Central Cluster and Connect to Ops Manager.

Deploy the MongoDBMultiCluster resource resource.¶

Set spec.credentials, spec.opsManagerconfigMapRef.name, and security settings and deploy the MongoDBMultiCluster resource. In the following code sample, duplicateServiceObjects is set to true to enable DNS proxying in Istio.

kubectl apply -f - <<EOF
apiVersion: mongodb.com/v1
kind: MongoDBMultiCluster
metadata:
 name: multi-replica-set
spec:
 version: 4.4.0-ent
 type: ReplicaSet
 persistent: false
 duplicateServiceObjects: true
 credentials: my-credentials
 opsManager:
   configMapRef:
     name: my-project
 security:
   certsSecretPrefix: <prefix>
   tls:
     ca: custom-ca
 clusterSpecList:
   - clusterName: ${MDB_CLUSTER_1_FULL_NAME}
     members: 3
   - clusterName: ${MDB_CLUSTER_2_FULL_NAME}
     members: 2
   - clusterName: ${MDB_CLUSTER_3_FULL_NAME}
     members: 3
EOF

The Kubernetes Operator copies the ConfigMap with the CA that you created in previous steps to each member cluster, generates a concatenated PEM secret, and distributes it to the member clusters.

Verify that the MongoDBMultiCluster resources are running.¶

1. For member clusters, run the following commands to verify that the MongoDB Pods are in the running state:

   copy

   kubectl get pods \
    --context=$MDB_CLUSTER_1_FULL_NAME \
    --namespace mongodb
   

   copy

   kubectl get pods \
    --context=$MDB_CLUSTER_2_FULL_NAME \
    --namespace mongodb
   

   copy

   kubectl get pods \
    --context=$MDB_CLUSTER_3_FULL_NAME \
    --namespace mongodb
   

2. In the central cluster, run the following command to verify that the MongoDBMultiCluster resource is in the running state:

   copy

   kubectl --context=$MDB_CENTRAL_CLUSTER_FULL_NAME \
     --namespace mongodb \
     get mdbmc multi-replica-set -o yaml -w
   

Renew the secret for a MongoDBMultiCluster resource.¶

Run this kubectl command to renew an existing secret that stores the certificates for the MongoDBMultiCluster resource:

kubectl --context $MDB_CENTRAL_CLUSTER_FULL_NAME \
--namespace=<metadata.namespace> \
create secret tls <prefix>-<metadata.name>-cert \
--cert=<resource-tls-cert> \
--key=<resource-tls-key> \
--dry-run=client \
-o yaml |
kubectl apply -f -