Configuring cross-site replication on the Main site

The cluster managed by the Operator should be able to reach external nodes of the Replica Sets. You can provide needed information in the replsets.externalNodes and sharding.configsvrReplset.externalNodes subsections of the deploy/cr.yaml configuration file. Following keys can be set to specify each external Replica, both for its Replica Set and Config Server instances:

• set host to URL or IP address of the external replset instance,
• set port to the port number of the external node (or rely on the 27017 default value),
• set priority to define the priority of the external node (2 is default for all local members of the cluster; external nodes should have lower priority to avoid unmanaged node being elected as a primary; 0 adds the node as a non-voting member),
• set votes to the number of votes an external node can cast in a replica set election (0 is default and should be used for non-voting members of the cluster).

Here is an example:

spec:
  unmanaged: false
  replsets:
  - name: rs0
    externalNodes:
    - host: rs0-1.percona.com
      port: 27017
      priority: 0
      votes: 0
    - host: rs0-2.percona.com
    ...
  sharding:
    configsvrReplSet:
      size: 3
      externalNodes:
        - host: cfg-1.percona.com
          port: 27017
          priority: 0
          votes: 0
        - host: cfg-2.percona.com
        ...

The Main site will be ready for replication when you apply changes as usual:

$ kubectl apply -f deploy/cr.yaml

Note

Don’t forget to expose instances of the Main cluster!

Getting the cluster secrets and certificates to be copied from Main to Replica

Main and Replica should have same Secrets objects (to have same users credentials) and certificates. So you may need to copy them from Main. Names of the corresponding objects are set in the secrets.ssl, secrets.sslInternal, secrets.users, and secrets.keyfile Custom Resource options. The default names are the following ones:

* `my-cluster-name-ssl` (SSL certificates for client connections),

* `my-cluster-name-ssl-internal` (SSL certificates for replication),

* `my-cluster-name-secrets` (user credentials),

* `my-cluster-name-mongodb-keyfile` (encryption key file).

If you can get Secrets from an existing cluster by executing the kubectl get secret command for each Secrets object you want to acquire:

$ kubectl get secret my-cluster-name-secrets -o yaml > my-cluster-secrets.yaml

Next remove the annotations, creationTimestamp, resourceVersion, selfLink, and uid metadata fields from the resulting file to make it ready for the Replica.

You will need to further apply these secrets on Replica.

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Last update: 2025-04-16