monorepo-setup-and-lerna

Monorepo Setup and Lerna with TypeScript:

• Understanding Monorepos:

  A monorepo is a single repository that can contain multiple packages or projects. It's beneficial for sharing code and resources across projects while maintaining separate deployment lifecycles.

• Lerna Introduction:

  Lerna is a tool that optimizes the workflow around managing multi-package repositories with git and npm. It helps with versioning, publishing, and managing dependencies of many packages within a single repository.

• Bootstrapping with Lerna:

  Use Lerna's bootstrap command to link dependencies between packages in the monorepo. This symlinks any cross-dependencies and installs all other dependencies.

• Yarn Workspaces:

  Lerna can be combined with Yarn workspaces to manage node_modules more efficiently, deduplicating the installation of shared dependencies.

• Hoisting:

  Lerna allows for hoisting, which means it can move dependencies up to the root node_modules to reduce install times and disk space usage.

• Single Version Policy:

  Enforce a single version policy where possible to ensure consistency and reduce the risk of dependency version conflicts across packages.

• Scoped Packages:

  Use scoped packages for internal libraries. For example, @yourcompany/button for a button component. Scopes help organize and clearly denote internal packages.

• TypeScript Project References:

  Utilize TypeScript's project references feature to manage dependencies and build order within a monorepo.

• Centralized TypeScript Configuration:

  Maintain a base tsconfig.json at the root, and extend it in individual packages for easier management of shared TypeScript configurations.

• Build Optimization:

  Use Lerna's ability to run scripts in parallel to optimize build times. For TypeScript, incremental builds and project references can also speed up the compilation process.

• Release Management:

  Lerna can automate the release process of packages, managing version bumping, changelog generation, git tagging, and npm publishing.

• Independent vs. Fixed Mode:

  Lerna can operate in two modes: fixed (where all packages get the same version number) or independent (where each package is versioned on its own). Choose based on how closely related and co-dependent the packages are.

• Testing in Monorepos:

  Configure your test runners to recognize the monorepo structure. Make sure tests for each package can be run in isolation and as part of a whole.

• Linting and Formatting:

  Set up ESLint, Prettier, or other code quality tools at the root level with the ability to run across all packages to ensure consistent coding styles.

• Import Paths:

  Use TypeScript path aliases to simplify imports and make them more readable, especially when importing across packages within the monorepo.

• Continuous Integration (CI):

  Configure your CI pipeline to handle the monorepo structure efficiently, potentially leveraging caching and selective builds to only build/test affected packages.