Yarn 2 support

[arcanis]

Hello! We plan to release Yarn 2 by the end of the month, so I want to open this thread to discuss how you'd see the upgrade path for the users of the Node image.

The 2.x releases will contain some breaking changes, so while our users will always be able to use the 1.x thanks to the yarnPath strategy, maybe you'll want to hold on until the next major (do Docker images have majors?). Or maybe a simpler strategy would be to just add "How to use Yarn 1 if I need to?" in the README?

[SimenB]

We currently see node majors as possibilities to make breaking changes to the images. Not sure what to do here, probably document how to install the version of yarn you want and bump for node 14 when it comes in april.

Is there a list of breaking changes?

[SimenB]

/cc @nodejs/docker

[arcanis]

The current changelog is slightly outdated as I'm working on it, but is here: https://github.com/yarnpkg/berry/blob/master/CHANGELOG.md

Overall the breaking changes are:

• The npm configuration isn't read anymore (everything in .yarnrc.yml)
• The bundleDependencies field is deprecated
• The package sources are kept in read-only stores by default
• Package boundaries must be respected
• Node scripts must be executed through yarn node ... instead of node ...

[SimenB]

Now that v2 is out what are our thoughts on this @nodejs/docker?

Personally I think going v2 by default from Node 14 (next major) makes sense. Maybe some doc updates for current versions? V12 is here until April 2022, so I think we need a plan or at least some docs

[nschonni]

I commented over on the other Yarn thread #777 (comment) that I think it might be better that Yarn has a separate Official Image.
They could probably take a bunch of what is in this repo, but only support a subset of the images

[SimenB]

Answered over there, off topic in this issue (although this issue would be redundant if we remove yarn, no-one is suggesting changing anything (beyond docs, maybe) at least until 14 is released in late April)

[eloytoro]

I'd like to add that by the looks of it there's a big chance that upgrading yarn to v2 in the node 14 image will introduce several breaking changes for projects that would result in the project not being able to execute because of changes unrelated to node itself

[arcanis]

Yes, I think it's perfectly fine if docker-node remains on 1.x after all.

Fwiw we're pivoting to a "trampoline model" where we only need a Yarn to be in the $PATH - just enough to bootstrap the per-project Yarn version by looking at the yarnPath setting (similar to gulp vs gulp-cli in the past, if you remember).

[Starefossen]

I agree! We should provide the yarn2 binary, but not replace yarn until the next major version of docker-node

[SimenB]

@arcanis do you think we should just ship that small script instead of the full yarn binary along with setting a default yarn policy? Would that mean people need a network connection to run yarn at all? Or just keep yarn v1 as-is and document how to use version policy for v2 (and future majors)?

[arcanis]

Would that mean people need a network connection to run yarn at all?

No; the binary will be checked into the repositories, so running any yarn command inside the project folder will use that without installing things from the network (it's handy; containers don't have to be rebuilt when upgrading Yarn).

do you think we should just ship that small script instead of the full yarn binary? Or just keep yarn v1 as-is and document how to use version policy for v2 (and future majors)?

I think for now keeping Yarn 1.x as-is and document the version policy is the most efficient way to move forward. Shipping just a small script is probably a bit too drastic at the moment, and assuming we will only get one shot to do this right I'd like to consider a few options first.

[SimenB]

That sounds good @arcanis, thanks!

[omeid]

I think this is perhaps a little off topic, but can someone please explain the rationale for the plethora of changes and features in a big drop without much beta/field testing?

If Yarn2 (which in all honestly should have been called something else) is going to replace Yarn in Node 14, I would expect a solid why rather than what we should change.

I think any decision regarding changing yarn without cost-benefits and rationale for change is far from prudent.