Lerna commands

Lerna commands #

I have been experimenting with Lerna to manage mono repositories in javascript projects.

Lerna provides a mechanism to run a command on each package in our mono repository with one cli. Here, I write down some of the commands I have been using:

• lerna boostrap: this commands links internal depencies between projects, similar to what yarn link, but for all packages of our mono repository. That way, when change happens in a package, all packages depending on it will have the use changes;
• lerna clean: it will clean the node_modules folder for all packages in our mono repository;
• lerna add a-dependency --scope=@scoped/package: will install a-dependency at our internal package which name (at package.json) is @scoped/package. A more realistic example, could be:
  • lerna add lodash --scope=utils;
• lerna add a-dependency --scope=@scoped/package --dev: same as the previous one, but a-dependency is installed as devDependencies (package.json);
• lerna run a-package-command: it will execute a-package-command for all packages at the mono repository. This a-package-command is expected to be defined on scripts property of package.json for each package existing at the mono repository. This is very useful, because lerna, besides, executing it for all packages, execute it in the correct order, for example, if we have package-a which depends from package-b, the command will be executed for package-b. If we think on package builds, it is very useful because package-b needs to be built before package-a. Some more realistic examples, could be:
  • lerna run build;
  • lerna run test;
  • lerna run lint;
• lerna run a-package-command --scope=@scoped/package: same as the previous one, but execute the command only for @scoped/package;
• lerna exec a-bash-command: same as run, but now the command does not to be defined at package.json, but it is expected to be executable;
• lerna publish from-package: publish packages on a defined registry. We could define the registry explicity using:
  • yarn lerna publish from-package --yes --registry http://localhost:4873;
• lerna changed: show which packages have changed since last publish;

Published 03 Jan 2021