[rush] installing "to" a workspace project still installs all packages for all projects (using pnpm v8)

[joelrbrandt]

Summary

With rush v5.102.0 and pnpm v8.6.12, using the --to or -t flag with rush install seems to have no effect.

Dependencies for all projects are still installed.

Repro steps

1. rush purge
2. rush install -t @myscope/myproject where @myscope/myproject is a workspace project

Expected result: only @myscope/myproject and its rush project dependencies have a complete node_modules folder

Actual result: all rush projects have a complete node_modules folder

Details

I found the (very old) issue #1669 and thought that perhaps this feature wasn't implemented.

However, I ran rush --debug install -t [my packge] and saw output that indicated rush is passing a --filter option to pnpm.

So, I think this is intended to work?

Specifically, this is the pnpm install command that prints out when I add --debug

$ rush --debug install -t @myscope/myproject

...

Invoking package manager: /Users/jbrandt/.rush/node-v18.16.0/pnpm-8.6.12/node_modules/pnpm/bin/pnpm.cjs install --store /Users/jbrandt/.pnpmcache --config.cacheDir=/Users/jbrandt/.pnpmcache --config.stateDir=/Users/jbrandt/.pnpmcache --no-prefer-frozen-lockfile --strict-peer-dependencies --config.ignoreCompatibilityDb --recursive --link-workspace-packages false --filter @myscope/myproject...

The main reason I want this feature to work is to speed up dependency installation in our CI/CD build steps that only build a portion of our monorepo.

Thank you for all the great work you do on rush! It is a delight to use!

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@microsoft/rush globally installed version?	5.101.1
rushVersion from rush.json?	5.102.0
pnpmVersion from rush.json?	8.6.12
useWorkspaces from rush.json?	true
Operating system?	reproed on Mac and Linux
Would you consider contributing a PR?	Yes, but not for this bug (no idea how to fix!)
Node.js version (node -v)?	18.16.0

[dmichon-msft]

This is a bug in pnpm@8. Our command to pnpm is correctly formatted and results in, e.g:

/workspaces/rushstack/common/temp (pnpm-latest) $ rush install --to @rushstack/heft
Running "pnpm install" in /workspaces/rushstack/common/temp

Scope: 14 of 130 workspace projects

However, pnpm itself then installs the dependencies in all projects.

See pnpm/pnpm#6300

Edit: looks like we may be able to work around this by passing --config.dedupe-peer-dependents=false when installing with --frozen-lockfile.