SSHing a running container

[fagiani]

I'm running pack built containers on AWS's ECS with Fargate and therefore I cannot access the host machine. I'm facing a issue that only happens in production and therefore I need to be able to log into the running task to debug.

If I use a EC2 provider as a host for the containers, I am able to log into with docker exec -it <container-id> /bin/bash and all ENVs will be there and I can leverage the use of console for instance and get rails console running (I'm using standard heroku's ruby buldpack).

As Fargate allows me to use a public IP, I've created a buildpack that will install sshd and create a private key so I can log into it. I am able to log in using ssh -i <my-rsa-id>.key heorku@<container-ip> and I will get a bash as well, but nothing is on the path and all ENVs from the Task Definition are not loaded at all...

Any clues on how to leverage whatever is done in the ENTRYPOINT or CMD of the docker run triggered by ECS and be able to get a behavior just like the docker exec -it ... command?

Any clues are highly appreciated!

[jkutner]

@fagiani Hello. You may need to set ForceCommand bash -c "HOME=/workspace /cnb/lifecycle/launcher $your_command" in your sshd_config. But in any case, you'll need to run /cnb/lifecycle/launcher at some point in the process, because that's what loads the buildpack environment.

I also created an ssh buildpack, in case you want to share code :)

Here's an example, where I've hard code this into a buildpacks (you might also find the web-tty buildpack helpful):
https://github.com/jkutner/web-tty-buildpack/blob/05c0221a34dc30068bdf825ccf9d32a41ff9e199/wetty/bin/build#L50

I hope this helps.