debug should support ruby

[briandealwis]

Please thumbs up this issue if you would be interested in Ruby debugging support.

[garytaylor]

I am desperate for a solution for remote development and skaffold provides everything I need apart from debugging support for ruby.

I am also interested in contributing to this feature given a steer from someone to start me off on the right path. I am experienced in both go and ruby.

[briandealwis]

Hi @garytaylor.

That would be great! This section of the docs provides a high-level description of how debug works, and this comment in the pkg/skaffold/debug package provides a lower-level description of the mechanics.

At its essence, you need to implement a new containerTransformer which does two things:

1. IsApplicable examines a container image to determine if it contains a program that the transformer can configure for debugging
2. Apply makes changes to the container definition to enable debugging

Adding a new language can be very straightforward or complex.

• For runtimes like the JVM, where the JVM includes debugging support out-of-the box, it's just a matter of recognizing that the container is a JVM app, and then setting the JAVA_TOOL_OPTIONS environment variable to enable debugging for a specific port.
• For runtimes like Go, we also need to install helper tools like Delve, which are distributed as container images as defined in the https://github.com/GoogleContainerTools/container-debug-support/ project. NodeJS would seem to be a simple case, as it has debugging support built-in with --inspect, but developers often use node-based launchers like npm run, nodemon, or tsnode, it's hard to enable debugging just on the application instance of node. So we install a node wrapper that uses heuristics to try to enable debugging only on the application instance.

A minor wrinkle is that the debugging transforms work for both Kubernetes and Docker runtimes, and there are additional tests for Kubernetes.

My suggestion is to take a look through the current implementation and then write up a small design proposal to document what's required for Ruby debugging, and sketch out how the implementation might look.