Yarn Workspaces has a bug that does not respect the location precedence of .npmrc / .yarnrc files to configure registry settings if you run a yarn command in a selected workspace. Consider the following situation:

• A .npmrc file located at home folder specifies a registry entry to use a private npm registry.
• A .npmrc file located at a project root specifies a registry entry to target a public npm registry like this registry=https://registry.npmjs.org.

In my current project, I have such a situation. The default situation is that projects need a registry setup to use the internal Artifactory. One project requires a setup to target the public npm registry. The problem of this project is that adding a dependency to a specific yarn workspaces package with the following command uses the wrong registry setup (the setup of ~/.npmrc instead of .npmrc file located at project root):

$ yarn workspace package-a add @rooks/use-previous

The problem is that wrong URLs are put into the yarn.lock file (targeting the private registry).

However, if you add a dependency globally with the -W flag, then the .npmrc precedence is honored:

$ yarn add @rooks/use-previous -W

This bug seems to exist for a very long time.

The following workarounds are possible:

• Use the --registry flag

$ yarn workspace package-a add @rooks/use-previous --registry 'https://registry.yarnpkg.com'

• Manually add the dependency to the package.json of package-a and run yarn install from the root folder of the project.
• Copy ~/.npmrc to every project root folder that need this registry setup and delete ~/.npmrc. If you have private settings (e.g., your user credentials) in the file, pay attention that you do not push the file to VCS (add it to .gitignore).
• Don't use yarn workspaces. E.g., use Lerna with npm.