Building a TypeScript Monorepo with Lerna
A monorepo is a single repository that contains multiple projects. This approach has gained popularity in recent years due to its numerous benefits, including simplified release processes, improved collaboration, and better discoverability. In this article, we will explore how to build a TypeScript monorepo using Lerna, a popular tool for managing multi-package repositories.
What is a TypeScript Monorepo?
A TypeScript monorepo is a codebase that contains multiple TypeScript projects, all managed within a single Git repository. Each project can have its own dependencies, build processes, and tests, while also being able to share common code and dependencies with other packages.
Benefits of a Monorepo
The monorepo approach offers several advantages, including:
- Code Reusability and Sharing: By keeping related projects in a single repository, it is easier to share code and improve code consistency across multiple projects.
- Simplified Release Process: Using a monorepo makes it possible to streamline the release process for all projects with a single build and deployment pipeline.
- Better Collaboration and Discoverability: With all projects in a single repository, it is easier for developers to communicate and collaborate on changes and issues.
What is Lerna?
Lerna is a popular tool written in JavaScript for setting and managing multi-package repositories for Node.js projects with npm and Git. Lerna has two modes: fixed and independent. The fixed mode keeps all versions of packages at the same level, while the independent mode allows different versions per package.
Setting up a TypeScript Monorepo with Lerna
To set up a TypeScript monorepo with Lerna, follow these steps:
- Install Lerna: Install Lerna as a global dependency using npm.
- Create a new repository: Create a new repository for your monorepo.
- Initialize Lerna: Initialize Lerna inside the repository using the
lerna initcommand. - Configure Lerna: Configure Lerna by creating a
lerna.jsonfile and specifying the packages and dependencies.
Configuring TypeScript
To configure TypeScript, create a tsconfig.json file in the root of the repository. This file will contain the configuration settings for the TypeScript compiler.
Building Packages with Lerna
To build packages with Lerna, use the lerna create command. This command will guide you through the creation of a new package.
Linking Packages with Lerna
To link packages with Lerna, use the lerna add command. This command will install the necessary dependencies and link the packages.
Publishing to npm
To publish the packages to npm, use the lerna publish command. This command will guide you through the publishing process.
Semantic Versioning and Conventional Commits
Lerna supports semantic versioning and conventional commits. Semantic versioning is a convention used for software versioning, while conventional commits is a formatting convention for commit messages.
Alternatives to Lerna
If you are looking for alternatives to Lerna, consider the following options:
- Nx: A popular tool for building, testing, and deploying code.
- Turborepo: A high-performance tool for managing monorepos.
- Rush: A tool for handling large groups of npm packages and dependencies.
By following these steps and using Lerna, you can build a TypeScript monorepo that simplifies the release process, improves collaboration, and increases discoverability.