custom-deployment

README

Kubernetes Custom Deployment Controller

Why?

This repo is an example of how you can write a custom controller for Kubernetes using the client-go package. This is rather educational code than something you should use as it is.

How to run?

You can start by creating a Pod:

In Kubernetes:

$ kubectl run custom-deployment --image=docker.io/mfojtik/custom-deployment:latest

In OpenShift you need to grant the service account rights to access deployments and replica sets cluster-wide. Be careful as this is horribly unsecure I feel bad for doing this:

$ oadm policy add-cluster-role-to-user admin system:serviceaccount:test:default --as=system:admin
$ kubectl run custom-deployment --image=docker.io/mfojtik/custom-deployment:latest

(the project name is 'test' in this case).

Once deployed and the Pod is running, it will observe any new/updated/deleted deployments and replica sets in the cluster (including itself ;):

[@dev] ~ # oc logs custom-deployment-3932074005-ttm95 -f
2016/11/09 16:28:49 Starting custom deployment controller
2016/11/09 16:28:49 Listing all ReplicaSets in cluster
2016/11/09 16:28:49 Listing all Deployment in cluster
2016/11/09 16:28:49 Watching all Deployments in cluster
2016/11/09 16:28:49 Adding deployment custom-deployment
2016/11/09 16:28:49 Watching all ReplicaSets in cluster
2016/11/09 16:28:49 Handling deployment test/custom-deployment
2016/11/09 16:28:49 Finished syncing deployment "test/custom-deployment" (546.3µs)
2016/11/09 16:28:50 Updating deployment custom-deployment
2016/11/09 16:28:50 Handling deployment test/custom-deployment
2016/11/09 16:28:50 Finished syncing deployment "test/custom-deployment" (29.73µs)

How to hack?

Just clone this repository and run make image. This should compile the latest binary and produce docker.io/mfojtik/custom-deployment:latest image you can use with commands described above.

To make sure you're using the local image append --image-pull-policy=Never to the kubectl run commands above.

TODO

• Get rid of pkg/util (needs to be included in k8s client-go or importable from main k8s without flags compilation errors
• Do something useful with Deployments (like add hooks)
• Add special annotation to k8s Deployments to ignore the Deployment managed by 3th party controller