[Chore]: investigate caching in platform build steps

[jsjoeio]

What is your suggestion?

to utilize caching in the platform build steps

Why do you want this feature?

speed up CI

Are there any workarounds to get this functionality today?

no

Are you interested in submitting a PR for this?

i will if no one else beats me to it

[ChiatzenW]

I am interested in helping, however I'm still relatively new so I prob need a few pointers. Where should I start looking for places for potential caching?

[jsjoeio]

@ChiatzenW thanks for offering to help! I would start here. This is a successful run of Build and it took 32m.

If you look through each job, you can see the total time for each. The ones over 5m are probably the ones that have areas where we can do some caching, specifically the macOS and Linux ones.

Let me know if you want more pointers!

[ChiatzenW]

I'm guessing we cannot skip the tests? As of current I see that various tests take up majority of the time and looks like aside from that we have the build process that seems to take up some time. Shall I work on eliminating building unnessecary parts where we can just use the last version?

[jsjoeio]

I'm guessing we cannot skip the tests? As of current I see that various tests take up majority of the time and looks like aside from that we have the build process that seems to take up some time.

Yes, we cannot skip the tests. However...we could only run the unit tests when there are changes to *.ts files. That's one small improvement. The e2e tests should only be run if there are changes to *.ts or lib/vscode or patches/*.

Shall I work on eliminating building unnessecary parts where we can just use the last version?

That sounds like a great idea! Before you do any work, can you share what you plan to do for this so we can make sure we're aligned?

[ChiatzenW]

hmm for tests I'm thinking maybe keep a variable somewhere and modify it every time tsc -w compiles? Or just calculate a SHA256 for all *.ts file and check them before we run the e2e tests.

As for building I'm thinking check if the package is already present and up-to-date and only install them when they are not?
I'm also curious if we can implement kind of like a Make-like system as I believe tsc -w --extendedDiagnostics can show files that triggered the recompilation fot the typescript part of the project and reduce the number of release artifacts we need to upload. I think the other parts like Code itself should be fairly well separated? So maybe we can keep them as is if only other things are modified. As of current building VScode and extensions takes 7m56s.

[jsjoeio]

That could work! We do something similar in coder/coder using a GitHub Action which might be a simpler approach: https://github.com/coder/coder/blob/main/.github/workflows/coder.yaml#L59-L76

I believe tsc -w --extendedDiagnostics can show files that triggered the recompilation fot the typescript part of the project and reduce the number of release artifacts we need to upload

That's an interesting idea! I wonder though if we still want to upload artifacts every time? Maybe going the cache build dependencies approach might be a better first step. Thoughts?

cc @code-asher in case you have any thoughts?

[ChiatzenW]

I looked into caching dependencies and it seems that it is already documented in the github actions documentation. Should I try following the steps here?

[jsjoeio]

@ChiatzenW great find! Yes, I'd say that seems like a good first step. Look at ci.yaml and see which steps could benefit from caching 👍🏼