Kubernetes Continous Deployment via a CRD Controller
We want to keep all our k8s manifests under version control and have our git system be the only interaction point for our deployments in production.
People should just git push and review PR
Then the question comes, how do you deploy.
kkcd
kkcd is a simple CRD based controller written in Python, just for rapid prototyping.
Once you create an App using a custom App object kind, the controller creates a CronJob with a gitRepo volume. The manifests repository is cloned by the git-repo volume and the CronJob runs kubecfg update. kubecfg is an improved kubectl apply.
That's it. See the original blog post
Every time you git push, kubecfg will apply the updates in a declarative way follwing the CronJob schedule.
The CRD is just a controller to use kubectl to manage your apps
Installation
kubectl create -f https://raw.githubusercontent.com/sebgoa/kkcd/master/kkcd.yaml
This will create a CRD and launch a controller
Write an App
apiVersion: bitnami.com/v1
kind: App
metadata:
name: cookie
spec:
repo: https://github.com/sebgoa/opencompose-jsonnet
We can extend the spec and add the CronJob schedule in there.
Create this app and watch the CronJob being created and soon your app will be running
kubectl create -f example.yaml
kubectl get apps
kubectl get cronjobs
kubectl get pods
Build
Using Bazel, build the controller image
bazel build :controller
push controller image to Docker hub
bazel run :push_controller
Note
Code is largely inspired by warm-image