MongoDB in Red Hat OpenShift Container Platform

An NFS server (NFSv4-only) is required to run these steps.

1. Provision storage for the MongoDB instance by creating a persistent volume. In this PoC use-case, NFS was used to make debugging easier. However, consider using OpenShift Data Foundation for reliability and performance in production environments. Make sure to adjust the value for the NFS_SERVER_IP variable in the following example:

   NFS_SHARE_CAPACITY="20Gi"
   NFS_SHARE_PATH="/nfs_share"
   NFS_SERVER_IP="?.?.?.?"
   STORAGE_CLASS_NAME="mongo-storage-class"
   
   cat <(echo '{
      "apiVersion": "v1",
      "kind": "PersistentVolume",
      "metadata": {
        "name": "nfs4mongo-pv-0001",
        "annotations": {
          "pv.kubernetes.io/bound-by-controller": "yes"
        },
        "finalizers": [ "kubernetes.io/pv-protection" ]
      },
      "spec": {
        "capacity": {
          "storage": "${NFS_SHARE_CAPACITY}"
        },
        "accessModes": [ "ReadWriteMany" ],
        "nfs": {
          "path": "${NFS_SHARE_PATH}",
          "server": "${NFS_SERVER_IP}"
        },
        "persistentVolumeReclaimPolicy": "Delete",
        "storageClassName": "${STORAGE_CLASS_NAME}"
      }
   }') > nfs-persistent-volume.json
   
   oc create -f nfs-persistent-volume.json

2. On the NFS server-side the user-id and group-id in the folder must match the user-id that the container runtime of mongoDB uses later (check the mongo-db-helm-with-replset.yaml and search for runAsUser). Run this command on the NFS server:

   chown 1000740005:1000740005 /mongo_share

3. In the Developer View of OpenShift, add a new project. In this example, the project is called mongodb-test-1. Switch to the new project.

   Note: This project name/namespace is used in later steps. If you use a different project name, remember to change the name in the subsequent commands.

4. To display the Helm chart in the Developer Catalog, add the Red Hat Helm chart as a Helm chart repository by clicking Helm Chart repositories > Create Helm Chart Repository to . Set the URL, to point to https://redhat-developer.github.io/redhat-helm-charts.

   
   
   
   
   

5. In Developer Catalog, click +Add and Helm Charts. Search for, then click IBM Mongodb Enterprise Helm > Install Helm Chart. Before you continue, edit the yaml file and replace the entire content with this yaml file:

   affinity: {}
   autoscaling:
     enabled: false
     maxReplicas: 100
     minReplicas: 1
     targetCPUUtilizationPercentage: 80
   database:
     adminpassword: admin123
     adminuser: adminuser
     name_database: testdb
   fullnameOverride: ''
   global:
     license: true
     persistence:
       claims:
         accessMode: ReadWriteMany
         capacity: 10
         capacityUnit: Gi
         mountPath: /data/db/
         name: mongodb-pvc-0001
         storageClassName: mongo-storage-class
       securityContext:
         fsGroup: 0
         supplementalGroup: 0
   image:
     pullPolicy: Always
     repository: quay.io/ibm/ibmz-mongodb-enterprise-database
     tag: "v4.4-rh7-s390x"
   imagePullSecrets: []
   ingress:
     annotations: {}
     controller: nginx
     host: mongotest.apps.ocp0.sa.boe
     tls: []
   nameOverride: ''
   nodeSelector: {}
   podAnnotations: {}
   podSecurityContext: {}
   replicaCount: 1
   resources: {}
   securityContext:
     runAsNonRoot: true
     # Must be in a certain range:
     runAsUser: 1000740005
   service:
     port: 27017
     type: ClusterIP
   serviceAccount:
     annotations: {}
     create: true
     name: mongod
   tolerations: []

6. Verify your installation.

   1. Go to the terminal of the spawned Pod, then run this command:

      mongo -u myUserAdmin -p password --authenticationDatabase admin

The installation of MongoDB spawns a single instance of mongod and is not in a replica set. The MongoDB connector that is used later in the Kafka setup expects a replica set and does not work without it.

In this section, the public image is slightly modified to make the mongod instance part of a replica set. This replica set has just a single instance which thinks that the other instances are currently down and promotes itself to be the primary.

Related resources:

• Convert a Standalone to a Replica Set

• "The $changeStream stage is only supported on replica sets" error while using mongodb-source-connect

This procedure edits the init script that sets up mongodb to change the behaviour. You can also modify /etc/mongod.conf instead.

The following commands require that podman is installed on the bastion.

1. Download and run the mongodb docker image with an interactive shell:

   podman run -it quay.io/ibm/ibmz-mongodb-enterprise-database:v4.4-rh7-s390x bash

2. Copy the mongo_init.sh to the local file system:

   podman cp CONTAINER:/var/log/mongodb/mongo_init.sh ./mongo_init.sh

3. Edit the mongo_init.sh script:

   1. Change the line that starts the mongod daemon to: mongod --replSet "rs0" -bind_ip_all.

   Note: --auth was removed because it also caused issues.

4. Make the mongo_init.sh script executable and readable by anyone:

   chmod 777 mongo_init.sh

5. Create a Dockerfile that uses the original image and replaces the mongo_init.sh script:

   FROM quay.io/ibm/ibmz-mongodb-enterprise-database:v4.4-rh7-s390x
   
   COPY mongo_init.sh /var/log/mongodb/mongo_init.sh

6. Build and tag the docker image:

   # cd into the dir with the Dockerfile
   podman build . -t custom-mongodb-1:latest

7. Push the image to the internal OpenShift image registry. When the oc get route command is not working check out: How to expose the registry.

   # Get the route to the internal OpenShift image registry
   HOST=$(oc get route default-route -n openshift-image-registry --template='{{ .spec.host }}')
   
   # Login to the internal docker image registry
   podman login -u admin -p $(oc whoami -t) ${HOST}
   
   NAMESPACE="mongodb-test-1"
   IMAGE_NAME="custom-mongodb-1:latest"
   LOCAL_IMAGE_NAME="localhost/${IMAGE_NAME}"
   REMOTE_IMAGE_NAME="${IMAGE_NAME}"
   podman push ${LOCAL_IMAGE_NAME} ${HOST}/${NAMESPACE}/${REMOTE_IMAGE_NAME}

8. Give the mongod service account permission to pull the image from the internal image registry mongodb-test-1 namespace:

   oc policy add-role-to-user \
     system:image-puller system:serviceaccount:mongodb-test-1:mongod \
     --namespace=mongodb-test-1

9. Deploy the Helm chart that now uses the custom image you pushed to the internal image registry:

   affinity: {}
   autoscaling:
     enabled: false
     maxReplicas: 100
     minReplicas: 1
     targetCPUUtilizationPercentage: 80
   database:
     adminpassword: admin123
     adminuser: adminuser
     name_database: testdb
   fullnameOverride: ''
   global:
     license: true
     persistence:
       claims:
         accessMode: ReadWriteMany
         capacity: 10
         capacityUnit: Gi
         mountPath: /data/db/
         name: mongodb-pvc-0001
         storageClassName: mongo-storage-class
       securityContext:
         fsGroup: 0
         supplementalGroup: 0
   image:
     pullPolicy: Always
     # CUSTOM IMAGE (WITH REPLICA SET ENABLED):
     repository: default-route-openshift-image-registry.apps.ocp0.sa.boe/mongodb-test-1/custom-mongodb-1
     tag: "latest"
   imagePullSecrets: []
   ingress:
     annotations: {}
     controller: nginx
     host: mongotest.apps.ocp0.sa.boe
     tls: []
   nameOverride: ''
   nodeSelector: {}
   podAnnotations: {}
   podSecurityContext: {}
   replicaCount: 1
   resources: {}
   securityContext:
     runAsNonRoot: true
     # Bust be in a certain range:
     runAsUser: 1000740005
   service:
     port: 27017
     type: ClusterIP
   serviceAccount:
     annotations: {}
     create: true
     name: mongod
   tolerations: []

   Note: If you get an image pull error, delete the pod. OpenShift automatically creates a new pod and tries the pull process again.

10. Open a terminal for the mongodb pod. Log in and then initiate the replica set:

    mongo -u myUserAdmin -p password --authenticationDatabase admin
    rs.initiate()

    Note: Make sure you wait until the mongodb transitioned from secondary to primary.

Follow the official documentation to Install MongoDB Enterprise Edition on Red Hat or CentOS. You can try it with a higher version than 4.4 but as this use-case uses version 4.4 on the OpenShift-side, version 4.4 is used on the LPAR-side for consistency.