k8s-mongo-operator

MongoDB Operator for Kubernetes.

Features

The following feature are currently available in this operator:

Create, update or delete MongoDB replica sets.
Automatically initialize the replica set configuration in the master node.
Schedule backups to Google Cloud Storage using a Google service account and mongodump.

Limitations

The current version has the limitations that shall be addressed in a later version:

The watch API from Kubernetes is currently not being used, as we want to remain responsive for creating backups in case no events are received. This means:
- We use list secret privilege to remove any admin operator secrets that are not used anymore. This is not part of the best practices.
- The solution is probably to listen to events with asyncio.
Mongo instances are not using SSL certificates yet.

Cluster interaction

Please refer to our simplified diagram to get an overview of the operator interactions with your Kubernetes cluster.

Deployment

To deploy this operator in your own cluster, you'll need to create some configuration files. An example of these configuration files can be found in kubernetes/operators/mongo-operator

As you can see there is a service account (mongo-operator-service-account) which has some specific permissions in the cluster. These permissions are registered in the cluster role and cluster role binding.

Lastly there is a deployment configuration to deploy the actual operator. Usually you'd use an image value like ultimaker/k8s-mongo-operator:master, or a specific version. All available tags can be found on Docker Hub.

Creating a Mongo object

To deploy a new replica set in your cluster using the operator, create a Kubernetes configuration file similar to this:

apiVersion: "operators.ultimaker.com/v1"
kind: Mongo
metadata:
  name: mongo-cluster
spec:
  mongodb:
    replicas: 3
  backups:
    cron: "0 * * * *" # hourly
    gcs:
      bucket: "ultimaker-mongo-backups"
      serviceAccount:
        secretKeyRef:
          name: "storage-service-account"
          key: json

Then deploy it to the cluster like any other object:

kubectl apply -f mongo.yaml

Testing locally

To run the tests in a local Kubernetes (MiniKube) cluster, we have created a simple test script.

Ensure you have the following tools installed on your system:

Docker
MiniKube v0.25.2 (please use this version specifically)

Then start a new MiniKube cluster using the following commands:

minikube start

Then you can run our test script to deploy the operator and execute some end-to-end tests.

Note that this script assumes there is a file google_credentials.json in this directory that will be uploaded to Kubernetes as the secret for the backups. You will need to download this file from Google in order to run the script.

./build-and-deploy-local.sh

You will also see the operator logs streamed to your console.

Contributing

Please make a GitHub issue or pull request to help us build this operator.

Maintainance

The repo is currently maintained by Ultimaker. Contact us via the GitHub issues for questions or suggestions.

Percona-Lab/k8s-mongo-operator