| [che-dev] Debugging in Che 7 |
Hey all,I'd like to open a discussion on how debugging in Che works, and how we ideally want it to work in general. As I've been working through our current devfiles for the 7.0.0 release, I've been figuring out debugging setups and found some configuration to be confusing from the perspective of a non-Che developer.
I've attached a diagram of the three modes of debugging currently used in Che + Theia:
- The first section represents the only local debugging possible: running the application being developed directly in the Theia container. This is typically impossible, due to either missing dependences or the tight memory limit on Theia. As a result, most debugging on Che is *remote*. I've opened an issue [1] to try and prevent Theia from offering this option by default as it can be misleading.
- The second section shows what I believe to be the ideal setup. Remote debugging works by connecting to the running application in the normally configured development container. This seems best, as the container should have enough memory allocated and normal user tasks operate there. As an example, this is how we currently support Java debugging. This mode is also (when it works) the easiest to configure, as the user is expected to interact with the main container only.
- The third section shows how debugging currently works for some languages. In this case, Theia has to launch another instance of the application in that language plugin's sidecar container, and connect the debugger there. While this works for our sample projects, it does have some drawbacks and poor UX: - the application *has* to fit in the sidecar's memory limit or it will get killed. In a general case it means the memory required for the application has to be duplicated (e.g. 1024Mi for both main and sidecar container) inflating workspace memory requirements - there can be e.g. port conflicts if the user has run the typical "run" task. In some debug configurations you have to look through a stack trace to figure out the problem
Devfiles operating this way are e.g. Golang, Python, and .NETThe third mode can also be the most confusing to configure (especially if you don't know the Che workspace structure already), as it's not immediately clear where your application is running (`ps aux` in the main container does not show it).
I think that following the 7.0 release, we should look into setting up workspaces so that the second option is used whenever possible, and we should try to set up Theia to lead users in this direction through the launch.json autocompletions. In general, I don't think a user should have to consider how many sidecars they are running, and what ends up being run in which sidecar. It would be very confusing if e.g. debugging kept crashing (due to memory limit) but regular "start" tasks worked without issue.
Does anyone have any thoughts or other options in mind? Cheers, Angel [1] - https://github.com/eclipse/che/issues/14091 (looking at it now, this needs to be rewritten to be more clear)
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