POC for externally triggering cleanup of lambda functions

[kelchm]

Based on previous discussions with @dl748 around #1090, I've implemented this proof of concept for how serverless-offline might allow other plugins to trigger a lambda cleanup for hot reloading.

Even without integration directly within something like serverless-webpack, this enables a custom plugin to hook the relevant event and then invoke the offline:functionsUpdated command that this PR adds (example).

Like with #1090, this still relies on useWorkerThreads: true and allowCache: true for this to actually work as expected. I'm also not really happy with the naming conventions here, please feel free to share any ideas if you have them.

[dherault]

@kelchm great work so far, I'm ready to merge. How could this be improved further?

[kelchm]

@dherault, thanks! It's a stupid hack but I think it is a good option to have available, particularly for large projects.

I unfortunately don't have much bandwidth to spare at the moment, but I'm happy to loop back on this in a week or two to get it polished up if you're onboard with the approach. Beyond adding documentation and test coverage, is there anything specific that you would like to see changed or improved?

EDIT: Sorry -- replied before I had any coffee. If you're happy with this as is, feel free to merge. I can still followup with some documentation additions in the future as my time allows.

[dl748]

This is a good first step, i think we should add the ability for the plugins to "announce" changed modules, that way only those modules can reload rather than every thing. Default (if no modules are provided) reload everything.

[dherault]

@kelchm I think it needs more polishing too, but the work done is good enough as is. If you cannot do more work in the following weeks I'll merge anyway. 😎
@dl748 Great feature proposal ✌️

[francisu]

@dherault I would love to see this go in as soon as possible. The serverless-webpack, allowCache is a very common use case as there are many lambda functions that depend on keeping globals alive (which allowCache emulates).

[dgurns]

Just bumping this. I'm using serverless-webpack 5.4.2, serverless-offline 6.9.0, and have allowCache: true to prevent the memory leak issue in #1119. Requests are back to ~50ms as opposed to ~1000ms.

However -- hot reload is not working. Is this PR still valid and a possible fix? If so would be great to get that working again.

@james-relyea tagging you in case this is related/helpful to the other thread in #1119. Thanks for getting this project moving again, very exciting to see new releases coming out.

[mitch-byb]

Bumping this, great proposal and solution - would love to see implemented.

Forked for now to allow us to cache while picking up changes in serverless-webpack compilation, but eager to move back to master.

[CorruptedHeart]

Any chance of this being merged in? Or what work is still required?

[dherault]

Ok let's go! I'm back on the project btw.

[dherault]

Published in v8.6.0 (in a few hours)