A Kubernetes Mutating Admission Webhook example, using Go. This is a companion repository for the Article Building a Kubernetes Mutating Admission Webhook: A “magic” way to inject a file into Pod Containers

This is proof of concept code, make sure to review carefully before using in a production system.

$ make test 

Define shell env:

# define env vars $ export CONTAINER_REPO=quay.io/my-user/my-repo $ export CONTAINER_VERSION=x.y.z 

Build/Push Webhook

$ make docker-build $ make docker-push 

• for this example you'll need to make the container repository public unless you'll be specifying ImagePullSecrets on the Pod

Deploy to K8s cluster

$ make k8s-deploy 

$ k run busybox-1 --image=busybox --restart=Never -l=hello=true -- sleep 3600 $ k exec busybox-1 -it -- ls /etc/config/hello.txt # The output should be: /etc/config/hello.txt $ k exec busybox-1 -it -- sh -c "cat /etc/config/hello.txt" # The output should be: Hello from the admission controller ! 

We successfully mutated our pod spec and added an arbitary volume/file in there, yay !

Delete all k8s resources

$ make k8s-delete-all