nesze/coco-mongodb repository overview

⁠MongoDB wrapper

MongoDB wrapper that runs in a 3 node replicaset.

For keeping the persistent data it uses 3 k8s Persistent Volumes, one for each replicaset. The PVs (EBS volumes) are managed manually.

⁠Mongo configurator

On the first start with empty data, MongoDB needs configuration to run in a replica set. On a Kubernetes cluster this is achieved automatically by a mongo configurator job⁠ that runs only on the first helm install in a cluster.

⁠Troubleshooting

⁠Access to the data

You can have access to the data by entering the pod and looking into /data/db

kubectl exec -it mongodb-x-...... /bin/bash
#inside the pod
cd /data/db

⁠Access to the data without mongodb running

If, for some reason (like restore debug) you need access to the data, but without the instance running you can use a temporary pod to mount mongo's persistent volume.

Here are the steps for it:

1. Stop the mongo instance

   kc scale deployment mongodb-x --replicas 0
   

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2. Create a file mongo-debug-x.yaml with the following contents:

   apiVersion: v1
   kind: Pod
   metadata:
     name: mongo-x-debug
   spec:
     tolerations:
     - key: "dedicated"
       operator: "Equal"
       value: "mongo"
       effect: "NoSchedule"
     affinity:
       nodeAffinity:
         requiredDuringSchedulingIgnoredDuringExecution:
           nodeSelectorTerms:
           - matchExpressions:
             - key: kube-aws.coreos.com/role
               operator: In
               values:
               - mongo-worker
     containers:
     - name: debug
       image: alpine
       # Just spin & wait forever
       command: [ "/bin/sh", "-c", "--" ]
       args: [ "while true; do sleep 30; done;" ]
       volumeMounts:
       - name: mongo-x-data
         mountPath: /data/db
     volumes:
      - name: mongo-x-data
        persistentVolumeClaim:
          claimName: "mongodb-pvc-x"
   

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3. Deploy the pod:

   kubectl apply -f mongo-debug-x.yaml
   

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4. Enter the pod and find the volume mounted in /data/db

   kubectl exec -it mongo-x-debug /bin/bash
   #inside the pod
   cd /data/db
   

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