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Install Percona Server for MongoDB in multi-namespace (cluster-wide) mode

By default, Percona Operator for MongoDB functions in a specific Kubernetes namespace. You can create one during installation (like it is shown in the installation instructions) or just use the default namespace. This approach allows several Operators to co-exist in one Kubernetes-based environment, being separated in different namespaces:

image

Still, sometimes it is more convenient to have one Operator watching for Percona Server for MongoDB Custom Resources in several namespaces.

We recommend running Percona Operator for MongoDB in a traditional way, limited to a specific namespace. But it is possible to run it in so-called cluster-wide mode, one Operator watching several namespaces, if needed:

image

Note

Please take into account that if several Operators are configured to watch the same namespace, it is entirely unpredictable which one will get ownership of the Custom Resource in it, so this situation should be avoided.

To use the Operator in such cluster-wide mode, you should install it with a different set of configuration YAML files, which are available in the deploy folder and have filenames with a special cw- prefix: e.g. deploy/cw-bundle.yaml.

While using this cluster-wide versions of configuration files, you should set the following information there:

  • subjects.namespace option should contain the namespace which will host the Operator,
  • WATCH_NAMESPACE key-value pair in the env section should have value equal to a comma-separated list of the namespaces to be watched by the Operator, and the namespace in which the Operator resides (or just a blank string to make the Operator deal with all namespaces in a Kubernetes cluster).

The following simple example shows how to install Operator cluster-wide on Kubernetes.

  1. First of all, clone the percona-server-mongodb-operator repository:

    $ git clone -b v1.13.0 https://github.com/percona/percona-server-mongodb-operator
    $ cd percona-server-mongodb-operator
    
  2. Let’s suppose that Operator’s namespace should be the psmdb-operator one. Create it as follows:

    $ kubectl create namespace psmdb-operator
    

    Namespaces to be watched by the Operator should be created in the same way if not exist. Let’s say the Operator should watch the psmdb namespace:

    $ kubectl create namespace psmdb
    
  3. Edit the deploy/cw-bundle.yaml configuration file to set proper namespaces:

    ...
    subjects:
    - kind: ServiceAccount
      name: percona-server-mongodb-operator
      namespace: "psmdb-operator"
    ...
    env:
             - name: WATCH_NAMESPACE
               value: "psmdb"
    ...
    
  4. Apply the deploy/cw-bundle.yaml file with the following command:

    $ kubectl apply -f deploy/cw-bundle.yaml -n psmdb-operator
    
  5. After the Operator is started, Percona Server for MongoDB can be created at any time by applying the deploy/cr.yaml configuration file, like in the case of normal installation:

    $ kubectl apply -f deploy/cr.yaml -n psmdb
    

    The creation process may take some time. When the process is over your cluster will obtain the ready status. You can check it with the following command:

    $ kubectl get psmdb
    
    Expected output
    NAME              ENDPOINT                                         STATUS   AGE
    my-cluster-name   my-cluster-name-mongos.psmdb.svc.cluster.local   ready    5m26s
    

Verifying the cluster operation

It may take ten minutes to get the cluster started. When kubectl get psmdb command finally shows you the cluster status as ready, you can try to connect to the cluster.

  1. You will need the login and password for the admin user to access the cluster. Use kubectl get secrets command to see the list of Secrets objects (by default the Secrets object you are interested in has my-cluster-name-secrets name). Then kubectl get secret my-cluster-name-secrets -o yaml command will return the YAML file with generated Secrets, including the MONGODB_DATABASE_ADMIN and MONGODB_DATABASE_ADMIN_PASSWORD strings, which should look as follows:

    ...
    data:
      ...
      MONGODB_DATABASE_ADMIN_PASSWORD: aDAzQ0pCY3NSWEZ2ZUIzS1I=
      MONGODB_DATABASE_ADMIN_USER: ZGF0YWJhc2VBZG1pbg==
    

    Here the actual login name and password are base64-encoded. Use echo 'aDAzQ0pCY3NSWEZ2ZUIzS1I=' | base64 --decode command to bring it back to a human-readable form.

  2. Run a container with a MongoDB client and connect its console output to your terminal. The following command will do this, naming the new Pod percona-client:

    $ kubectl run -i --rm --tty percona-client --image=percona/percona-server-mongodb:5.0.11-10 --restart=Never --env="POD_NAMESPACE=psmdb" -- bash -il
    

    Executing it may require some time to deploy the correspondent Pod.

  3. Now run mongo tool in the percona-client command shell using the login (which is normally databaseAdmin) and a proper password obtained from the Secret. The command will look different depending on whether sharding is on (the default behavior) or off:

    $ mongo "mongodb://databaseAdmin:databaseAdminPassword@my-cluster-name-mongos.psmdb.svc.cluster.local/admin?ssl=false"
    
    $ mongo "mongodb+srv://databaseAdmin:databaseAdminPassword@my-cluster-name-rs0.psmdb.svc.cluster.local/admin?replicaSet=rs0&ssl=false"
    

Last update: 2022-09-21