How to SSH to docker container in kubernetes cluster?

I am fairly new to the Google Cloud platform and Docker and set-up a cluster of nodes, made a Dockerfile that copies a repo and runs a Clojure REPL on a public port. I can connect to it from my IDE and play around with my code, awesome!

That REPL should however probably be tunneled through SSH, but here is where my problem starts. I can't find a suitable place to SSH into making changes to the repo that Docker runs the REPL on:

• The exposed IP just exposes the REPL service (correct kubernetes term?) and does not allow me to SSH in.
• Neither does the cluster master endpoint, it gives me a public key error even though I've followed the Adding or removing SSH keys for all of the instances in your project part here.

I'd like to modify the source files via SSH, but I'll need to access the Docker code repository. I'm not sure how to proceed.

I understand this isn't exactly a typical way to deploy applications so I am not even sure it's possible to have multiple nodes work with a modified docker codebase (do the nodes share the JVM somehow?).

Concretely my question is how do I SSH into the docker container to access the codebase?

For more recent Kubernetes versions the shell command should be separated by the --:

kubectl exec -it <POD NAME> -c <CONTAINER NAME> -- bash

Please note that bash needs to be availalble for execution inside of the container. For different OS flavours you might need to use /bin/sh, /bin/bash (or others) instead.

The command format for Kubernetes 1.5.0:

kubectl exec -it <POD NAME> -c <CONTAINER NAME> bash