`volta install corepack` doesn't provide corepack's `yarn`

[gamoutatsumi]

I installed https://github.com/nodejs/corepack.
Normally corepack provide yarn binary, but using volta, yarn is linked to volta-shim.
Volta has not compatibility for corepack?

[charlespierce]

Hi @gamoutatsumi, unfortunately, I think it's true that Volta isn't compatible with globally installing corepack. Ultimately, both Volta and corepack are looking to solve the same problem: Making a package manager available to you without relying on a specific version being installed.

Volta's has special-case handling for the package managers, so when you run yarn it uses Volta's logic for detecting the package manager, as opposed to delegating to Corepack.

[ljharb]

Given that node is planning to integrate corepack by default, you may want to consider supporting it.

[charlespierce]

Yeah, I think we'll need to evaluate how to do a partial passthrough for when Node starts shipping Corepack. We need to do it in a way that won't break down on older Node versions that don't include Corepack. I don't know that we can reasonably support the 3rd-party package version without a significant refactor, however, and once it's included by default the value-add is quite a bit lower.

[eugene1g]

corepack is now bundled with Node as of 16.9.0 (https://github.com/nodejs/node/blob/master/doc/changelogs/CHANGELOG_V16.md#corepack) but not yet enabled by default.

Today we use Volta to control versions for both Node and Yarn, but we now plan to use Volta for Node (in dev / prod), and corepack for Yarn (in dev). Does Volta plan to support this dual proxying, or is that getting too complex?

[cspotcode]

I was able to make this work as follows:

npm install -g corepack

# Specifying an explicit install-directory makes corepack overwrite volta's yarn shims, which is what we want
corepack enable --install-directory ~/.volta/bin

# Now yarn should be controlled by corepack
yarn set version berry

[charlespierce]

Looking at how we handle the passthrough behavior, I think that we can make Volta interop with Corepack nicely with a minimal change. It should work as it currently does for Node without Corepack (showing a nice error about missing Yarn), while with Corepack it will delegate to that behavior if you run yarn.

[sirreal]

Corepack is bundled with recent node versions. The documentation suggests it's available as an executable just like node:

… run corepack enable
… run corepack prepare

It's experimental at the moment, but given Corepack is expected to be core functionality, when installing a compatible version of node should volta shim corepack to the bundled version as well?

[charlespierce]

@sirreal Yeah, once we have support for calling the Corepack version of yarn (Started in #1024, got blocked on showing a proper error message so will need some design work), I think we'll also need to add a shim for corepack itself. That should be relatively straightforward, and use the same logic as the npx executable, showing a helpful error message if you're on an older version of Node that doesn't include corepack.

[brandonchinn178]

IIUC, the only benefit of using corepack's yarn is because corepack looks at the packageManager key in package.json and automatically uses the right version of yarn (instead of checking in the yarn binary). In lieu of getting some sort of compatibility between volta and corepack, wouldn't it be sufficient to update volta to support looking at packageManager and using the same logic?

[charlespierce]

@brandonchinn178 Yeah, that definitely would be an intermediate approach to help improve compatibility. There's a bit of design that would need to happen there (we'd definitely love a small RFC!) around how we handle volta pin when the version is pulled from packageManager instead of volta.

Somewhat related to #282, which tracks the potential for pulling version information from different sources.