kubectl-debug plugin

This plugin demonstrates how to use ephemeral containers to debug running pods. The kubectl debug command will add an ephemeral container using an arbitrary container image to the specified pod which can then be attached and used as a shell.

Note: This is proof-of-concept code and not an officially supported Google product. The functionality of this plugin should eventually be included in kubectl proper.

Running

# assumes you have a working KUBECONFIG
$ GO111MODULE="on" go build cmd/kubectl-debug.go
# place the built binary somewhere in your PATH
$ cp ./kubectl-debug /usr/local/bin

# Create a pod to debug
$ cat example.yaml
apiVersion: v1
kind: Pod
metadata:
  name: debugtest
spec:
  shareProcessNamespace: true
  restartPolicy: Always
  containers:
  - name: nginx
    image: nginx:alpine
    stdin: true
    tty: true
  - name: two
    image: gcr.io/google_containers/pause-amd64:3.0
    stdin: true
    tty: true
$ kubectl create -f example.yaml
pod/debugtest created

# Attach a debian debug image
$ kubectl debug debugtest --image alpine --attach
If you don't see a command prompt, try pressing enter.
/ # ps auxww
PID   USER     TIME  COMMAND
    1 root      0:00 /pause
    6 root      0:00 nginx: master process nginx -g daemon off;
   11 101       0:00 nginx: worker process
   12 101       0:00 nginx: worker process
   13 101       0:00 nginx: worker process
   14 101       0:00 nginx: worker process
   15 101       0:00 nginx: worker process
   16 101       0:00 nginx: worker process
   17 101       0:00 nginx: worker process
   18 101       0:00 nginx: worker process
   19 root      0:00 /pause
   24 root      0:00 /bin/sh
   29 root      0:00 ps auxww
/ #

Cleanup

You can "uninstall" this plugin from kubectl by simply removing it from your PATH:

$ rm /usr/local/bin/kubectl-debug