Deploying a MongoDB cluster can be a challenge because you have to account for numerous configurations like setting up the instances, providing backups, networking, and more. The MongoDB Enterprise Kubernetes Operator minimizes and standardizes these steps in your Kubernetes or Red Hat OpenShift environments, which simplifies deploying a MongoDB database in your own environment.

With the operator, you can deploy MongoDB resources using the Kubernetes API and manage them natively. In this tutorial, learn how to install and use the operator and deploy a replica set. You will also secure the MongoDB deployment with authentication and manage users natively in Kubernetes or OpenShift. You will also secure the database by adding TLS with the help of cert-manager. Cert-manager is another operator that allows you to manage certificates natively in the same environment.

This tutorial shows you how to:

• Use the Red Hat Marketplace and install operators
• Install MongoDB Enterprise Advanced Operator in OpenShift and deploy a MongoDB replica set using the operator.
• Secure the MongoDB deployment with authentication and add TLS using cert-manager.
• Connect an example microservice with the secure MongoDB deployment.

Flow

1. Register the OpenShift cluster with Red Hat Marketplace.
2. Install MongoDB Enterprise Operator in OpenShift.
3. Deploy an Ops Manager platform using the provided APIs from the operator.
4. Deploy the MongoDB replica set deployment which is also managed by the Ops Manager.
5. Install the cert-manager operator which helps manage TLS certificates natively in OpenShift.
6. Create certificates for each replica of the MongoDB deployment.
7. Install the created certificates and enable TLS and authentication on the MongoDB deployment.
8. Add a MongoDB user for the MongoDB deployment with the operator.
9. Deploy and connect an example Node.js application to the secured MongoDB database.

Prerequisites

• OpenShift cluster
• OpenShift CLI (oc)

Steps

1. Clone the repo.
2. Install MongoDB Enterprise Advanced Operator
3. Install MonogDB Resources
4. Install cert-manager
5. Generate Certificates and enable TLS
6. Deploy sample application

Step 1. Clone the repo

1. Clone the openshift-mongodb-enterprise-operator-example repo locally.

   In a terminal, run:

    git clone https://github.com/IBM/openshift-mongodb-enterprise-operator-example
   
    cd openshift-mongodb-enterprise-operator-example
   

2. Make sure you are also logged in to your OpenShift cluster as an admin. Then create a project for your MongoDB resources.

    oc new-project mongodb
   

Step 2. Install MongoDB Enterprise Advanced Operator

1. To use software from the Red Hat Marketplace, you need to register your cluster in the marketplace. This allows the cluster to pull the container images that are used by the software. To register your OpenShift cluster on IBM Cloud, you can follow the instructions here: Register OpenShift cluster with Red Hat Marketplace

   IMPORTANT: For OpenShift on IBM Cloud clusters, you must reload all your worker nodes for the pull secrets from the registration step to apply. Then you can proceed below.

2. Once you're done registering your OpenShift cluster, you can now install the MongoDB Enterprise Advanced Operator in the Marketplace. Go to the main page of the Red Hat Marketplace and search for MongoDB.

   

3. Select the MongoDB Enterprise Advanced from IBM and select the Free Trial option to get a 30-day trial. Next, you should be redirected to the software page. If not, click on the Workspace > My Software at the top of the page and select MongoDB Enterprise.

   

4. On the Operators tab, you can click on Install operator and choose your cluster for the Target clusters section. For the Namespace Scope, from the drop-down select the mongodb namespace which you created in step 1.

   

5. You should now be back on the Operators tab on your MongoDB Enterprise software page. The Status says Up to date when it's ready.

   

When you see that status, move on to Step 3.

Step 3. Install MonogDB resources

Now that you've installed the MongoDB Enterprise Operator, you can deploy the custom resources it provides (MongoDB Deployment, Ops Manager, Users). To deploy a MongoDB, you need an Ops Manager. The Ops Manager is the management platform for your MongoDB clusters.

1. Review the deployment/0-ops-manager.yaml file which deploys the Ops Manager and a secret for the initial login. Deploy using the command:

    oc apply -f deployment/0-ops-manager.yaml
   

2. The Ops Manager will also deploy a database with 3 replicas. Wait for the STATE (OPSMANAGER) to be Running.

   To check, use:

    oc get opsmanagers
   
    NAME          REPLICAS   VERSION   STATE (OPSMANAGER)   STATE (APPDB)   STATE (BACKUP)   AGE   WARNINGS
    ops-manager              4.2.8     Running              Running         Pending          14m
   

3. Now, you can go to the Ops Manager dashboard. To get the URl:

    oc get svc
   
    NAME                  TYPE           CLUSTER-IP       EXTERNAL-IP    PORT(S)          AGE
    ...
    ops-manager-svc-ext   LoadBalancer   172.21.118.38    169.xx.xx.xx   8080:31643/TCP   11m
   

4. Get the EXTERNAL-IP and open your browser on 169.xx.xx.xx:8080. Log in with your credentials you set in deployment/0-ops-manager.yaml, and follow the prompts to configure the Ops Manager. You can choose to use the default values.

   Then, what you'll need to deploy a MongoDB cluster is an API key. It is recommended to use an Organization API key instead of a global one.

5. To create an Organization, click on the upper right corner that says your account name and select Organizations. Click on + New Organization to create a new one. Name it example-organization or another name you choose.

   

6. To create the API key, go to Access > API Keys and create a new one. Grab the Public Key and place it in the user value in deployment/1-ops-manager-config-secret. Then, make sure to set the Organization Permissions to Organization Owner. Enter a short description.

7. Next, copy the Private Key in the publicApiKey value in deployment/1-ops-manager-config-secret. You will also need to add an API allowlist entry. Add 172.30.0.0/16, because this is the internal IP addresses of the pods in OpenShift on IBM Cloud.

   

8. For the ConfigMap on deployment/1-ops-manager-config-secret, the values for the following are:

   • baseUrl is from oc get om ops-manager -o jsonpath='{.status.opsManager.url}'
   • orgId is in your Organization dashboard which you can find navigating to Settings > Organization ID
   • projectName is the project name you want

9. Then you can create the secret and ConfigMap using:

    oc create -f  deployment/1-ops-manager-config-secret.yaml
   

10. Create the MongoDB deployment:

     oc apply -f deployment/2-mongodb-deployment.yaml
    

11. This creates a replica set with 3 replicas. To check the status:

     oc get mongodb
    
     NAME            TYPE         STATE     VERSION     AGE
     example-mongo   ReplicaSet   Running   4.2.2-ent   4h18m
    

Wait for its STATE to be Running. You can also view the pods that these custom resources created. You should see the new MongoDB in your Ops Manager dashboard. Notice that TLS is not enabled. You can enable it by generating certificates and adding them in your cluster. The next steps guide you in creating the certificates using cert-manager.

Step 4. Install cert-manager

cert-manager is a native Kubernetes certificate management controller that automates the management and issuance of TLS certificates from various issuing sources. We're going to use cert-manager to issue self-signed certificates.

1. Using the OperatorHub in OpenShift, look for cert-manager and install it. Then create the namespace for its resources.

    oc create namespace cert-manager
   

2. Install the cert-manager components.

    oc apply -f cert-manager/cert-manager.yaml
   

3. Make sure all the pods are running.

    oc get pods -n cert-manager
   
    NAME                                       READY   STATUS    RESTARTS   AGE
    cert-manager-54d75944-j25dl                1/1     Running   0          58s
    cert-manager-cainjector-745cf7d9b6-9x82s   1/1     Running   0          58s
    cert-manager-webhook-7cffc6c677-cphsr      1/1     Running   0          58s
   

Step 5. Generate certificates and enable TLS

1. To generate self-signed certificates, you can generate a certificate authority of your own using the tool openssl. Use the following commands to generate the CA's key pair.

    openssl genrsa -out ca.key 4096
    openssl req -x509 -new -nodes -key ca.key -days 3650 -reqexts v3_req -extensions v3_ca -out ca.crt
   

2. Create a TLS secret using the generated files ca.crt and ca.key.

    oc create secret tls ca-key-pair --cert=ca.crt --key=ca.key
   

3. You can now create the Issuer resource from cert-manager using the secret. Review the cert-manager/issuer.yaml file and deploy and check its status:

    oc apply -f cert-manager/issuer.yaml
   
    oc get issuer
   
    NAME                READY   AGE
    mongodb-ca-issuer   True    18s
   

4. Next, grab the hostnames of the replicas of your MongoDB. You can find them using your Ops Manager. Navigate to the Organization > Project you created and click on the MongoDB deployment.

   

5. Take note of the hostnames. Review the cert-manager/certificates.yaml and you should find 3 Certificate resources defined. Make sure each certificate corresponds to the hostnames of your replicas.

6. Deploy the certificates:

    oc apply -f cert-manager/certificates.yaml
   

7. You can get the certificates managed by cert-manager using this command:

    oc get certificates
   
    NAME              READY   SECRET            AGE
    example-mongo-0   True    example-mongo-0   4s
    example-mongo-1   True    example-mongo-1   3s
    example-mongo-2   True    example-mongo-2   2s
   

8. You can also find the TLS secrets that were created by using:

    oc get secret | grep example-mongo
   
    example-mongo-0                                    kubernetes.io/tls                     3      2m14s
    example-mongo-1                                    kubernetes.io/tls                     3      2m14s
    example-mongo-2                                    kubernetes.io/tls                     3      2m14s
   

9. The MongoDB expects PEM files (combination of certificate and key). You can save them locally with the format of the filenames like "mongodbName-replicaNumber-pem" (e.g. example-mongo-0-pem).

   You can grab the certificates' secrets and save them using the following commands:

    oc get secret example-mongo-0 -o jsonpath='{.data.tls\.crt}{.data.tls\.key}' | base64 --decode > example-mongo-0-pem
   
    oc get secret example-mongo-1 -o jsonpath='{.data.tls\.crt}{.data.tls\.key}' | base64 --decode > example-mongo-1-pem
   
    oc get secret example-mongo-2 -o jsonpath='{.data.tls\.crt}{.data.tls\.key}' | base64 --decode > example-mongo-2-pem
   

10. Create the files example-mongo-0-pem,example-mongo-1-pem,example-mongo-2-pem. Now, you need to create the certificate with the PEM files. The secret name should be "mongodbName-cert" format.

11. The following command creates an example-mongo-cert with the PEM files from above.

     oc create secret generic example-mongo-cert --from-file=example-mongo-0-pem --from-file=example-mongo-1-pem --from-    file=example-mongo-2-pem
    

12. You also need to create a ConfigMap of your custom CA certificate. You can use the ca.crt file that you created:

     oc create configmap custom-ca --from-file=ca-pem=ca.crt
    

13. Now you can enable TLS on your MongoDB. Uncomment the security block on the deployment/2-mongodb-deployment.yaml. This enables TLS using your custom-ca and also enables authentication using SCRAM. Apply your new changes:

     oc apply -f deployment/2-mongodb-deployment.yaml
    

14. This process can take time as the Mongo agents enable both TLS and authentication. Check the state using oc get mongodb again.

     oc get mongodb
    
     NAME            TYPE         STATE     VERSION     AGE
     example-mongo   ReplicaSet   Running   4.2.2-ent   4h18m
    

    Also, in your Ops Manager, your deployment should show that TLS and AUTH is enabled:

    

    Then you can add a user using the custom resource that the operator provides.

15. Review the deployment/3-mongodb-user.yaml. This creates a secret for the password and a MongoDBUser named mongodb-example-user. The YAML file also defines the roles it has and in this case, it has privileges of readWrite in example database. Apply the YAML file:

     oc apply -f deployment/3-mongodb-user.yaml
    

16. To check the status, execute the command below. The STATE should be Updated. You can also check the newly created user in your Ops Manager. It should also show up in MongoDB Users in your Project > Security.

     oc get mongodbusers
    
     NAME                   STATE     AGE
     mongodb-example-user   Updated   72s
    

Now that you have a secure MongoDB deployment, follow the steps below to connect to this database from your applications or microservices in your OpenShift cluster.

Step 6. Deploy a sample application

You can connect your microservices with the secured MongoDB deployment. An example Node.js application is provided in this repo: example-applications/nodejs.

1. You can build and push the example app as a container image in Docker Hub.

    cd example-applications/nodejs
    docker build -t <your-dockerhub-username>/example-nodejs-mongodb:1.0 .
    docker push <your-dockerhub-username>/example-nodejs-mongodb:1.0
   

2. Review the example-applications/nodejs/deployment.yaml file. The first item is a secret. Review the values for:

   • MONGODB_REPLICA_HOSTNAMES. You can find them using your Ops Manager and go to the Organization > Project you created and click on the MongoDB deployment. Make sure to separate them using commas.
   • MONGODB_REPLICA_SET is your MongoDB deployment name.
   • MONGODB_USER, MONGODB_PASSWORD, MONGODB_AUTH_DBNAME are the credentials you created using deployment/3-mongodb-user.yaml Make sure MONGODB_DBNAME is the database where your user has readWrite privileges.
   • You can leave MONGODB_CA_PATH as is. The deployment resource in the yaml file mounts the ca-key-pair secret which you created in Step 5.

3. Change the container image name (anthonyamanse/example-nodejs-mongodb:1.0) of the deployment in the same yaml file with the container image name you just pushed.

4. You can now deploy the example application:

    oc apply -f deployment.yaml
   

5. Access the application by getting the route:

    oc get routes
    NAME                   HOST/PORT                                                                                                                           PATH   SERVICES               PORT    TERMINATION   WILDCARD
    example-node-service   example-node-service-dev-db.anthony-marketplace-dev-f2c6cdc6801be85fd188b09d006f13e3-0000.us-    south.containers.appdomain.cloud          example-node-service   <all>                 None
   

6. Open the route example-node-service-...cloud/api-docs (Add the path /api-docs) in your browser. You should see a Swagger UI. Try and add a new transaction using "POST /transactions".

   

7. You should see a 201 response. You can now try "GET /transactions" and you can also see the MongoDB documents using your Ops Manager. Go to your Organization > Project > Your Deployment, then Data tab

   

Conclusion

Hopefully this tutorial has shown you how using the MongoDB Enterprise Kubernetes Operator simplified the process of securing the MongoDB deployment with authentication and managing users natively in Kubernetes or OpenShift.