[Bug?]: the 'postinstall' script is not executed when running 'yarn install'

[YaoHuiJi]

Self-service

• I'd be willing to implement a fix

Describe the bug

The 'postinstall' script is not automatically executed when running 'yarn install', but 'yarn run postinstall' works

package.json

"scripts": {
		"postinstall": "echo '@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@'",
	},

.yarnrc.yml

nodeLinker: node-modules
enableScripts: true
yarnPath: .yarn/releases/yarn-4.4.1.cjs

yarn install

➤ YN0000: · Yarn 4.4.1
➤ YN0000: ┌ Resolution step
➤ YN0000: └ Completed in 0s 494ms
➤ YN0000: ┌ Post-resolution validation
➤ YN0060: │ eslint is listed by your project with version 9.10.0 (pc6ea3), which doesn't satisfy what eslint-plugin-import and other dependencies request (but they have non-overlapping ranges!).
➤ YN0086: │ Some peer dependencies are incorrectly met by your project; run yarn explain peer-requirements <hash> for details, where <hash> is the six-letter p-prefixed code.
➤ YN0086: │ Some peer dependencies are incorrectly met by dependencies; run yarn explain peer-requirements for details.
➤ YN0000: └ Completed
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed in 4s 987ms
➤ YN0000: ┌ Link step
➤ YN0000: └ Completed in 1s 410ms
➤ YN0000: · Done with warnings in 7s 66ms

yarn run postinstall

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

To reproduce

run 'yarn install'

Environment

System:
OS: macOS 13.6.1
CPU: (4) x64 Intel(R) Core(TM) i5-4308U CPU @ 2.80GHz
Binaries:
Node: 20.10.0 - /private/var/folders/4w/69gblgzx3111pg1w3t6whsgm0000gn/T/xfs-c44d8ae0/node
Yarn: 4.4.1 - /private/var/folders/4w/69gblgzx3111pg1w3t6whsgm0000gn/T/xfs-c44d8ae0/yarn
npm: 10.2.3 - /usr/local/bin/npm
npmPackages:
jest: ^29.6.3 => 29.7.0

Additional context

No response

[clemyan]

Output of build scripts are hidden unless it failed or enableInlineBuilds is set.

Also, build scripts are not run on every install. A package's build script is only run if:

• it was just added to the project
• one of its dependencies (direct or transitive) changed, or
• the script failed the last time it ran

[Nantris]

What about when I define a postinstall in my own project though? That doesn't seem to run reliably either. Is there some way to get it to run rather than to rely on a workspace package in the monorepo to run this postinstall?

[clemyan]

The conditions I wrote above still apply. A postinstall script of a workspace runs only if the workspace itself satisfies one of three.

[ClementValot]

Note: It appears like the behavior is different on Windows and MacOS, just tested on two machines with the same config:

yarn 
rm -rf node_modules/some-package
yarn 

On the second yarn, postinstall is triggered on Windows, but not on MacOS.

@clemyan what do you think?