How to install package with local path by Yarn? It couldn't find package

In my package.json I'm pointing local package my-custom-i18n by its relative path:

package.json

"dependencies": {
 "core-js": "^2.4.1",
 "my-custom-i18n": "./../MyProject.Shared/myproject-i18n",
 "rxjs": "5.0.0-beta.12",
 ...
}

npm install installs packages correctly, but yarn has problem with it and simply cannot find this package:

yarn output

$ yarn
yarn install v0.15.1
info No lockfile found.
[1/4] Resolving packages...
error Couldn't find package "myproject-i18n" on the "npm" registry.
info Visit http://yarnpkg.com/en/docs/cli/install for documentation about this command.

I see that it looks it on the npm registry, where this package doesn't live.

Question

Is there any change to use yarn with local packages? By local packages I mean packages pointed by relative path as my-custom-i18n.

For yarn version < 2.x

Yarn requires prefix file: for local packages.

For relative path:

yarn add file:./../your-project

For absolute path

yarn add file:/dev/your-project

For your example, dependency in package.json would be declared as follows:

 "my-custom-i18n": "file:./../MyProject.Shared/myproject-i18n",

This works both for Yarn and NPM as well.

It is incompatibility with NPM client, Yarn team is aware and declared to support this behavior - reference on GitHub issue.

Update:

Since v0.21.0 release, file: prefix is not needed. See pull-request with fix and changelog.

If you want to simply link to the local package (so changes in the local package are picked up without reinstalling):

yarn add link:./../your-project

See more on yarn docs