How to migrate from lerna to pnpm

Migrating from Lerna to pnpm involves restructuring project management, optimizing dependency management, and improving workflow efficiency. The following is a detailed and well-organized migration process, illustrated with a specific example.

Step 1: Assess the Existing Lerna Project Structure

Before initiating the migration, conduct a comprehensive assessment of the current Lerna-based project. This includes understanding dependencies between all packages, the build workflow, and the release process.

Example: Assume we have a monorepo managed by Lerna containing three packages: package-a, package-b, and package-c. Both package-a and package-b depend on package-c.

Step 2: Install and Configure pnpm

After confirming the project structure and dependencies, install pnpm. pnpm can be installed using npm:

bash
npm install -g pnpm

Next, to use pnpm within the monorepo, create a pnpm-workspace.yaml file to define workspace settings.

Example: Create pnpm-workspace.yaml in the project root with the following content:

yaml
packages:
  - 'packages/*'

Step 3: Migrate Dependency Management for Each Package

Migrate dependency management from Lerna to pnpm for each package's package.json. This involves using pnpm commands to install dependencies and ensuring all internal dependencies are correctly configured using pnpm's workspace linking.

Example: For package-a, if it depends on package-c, specify the dependency in package-a's package.json using pnpm syntax:

json
"dependencies": {
  "package-c": "workspace:^1.0.0"
}

Step 4: Adjust CI/CD Scripts

During migration, update CI/CD scripts to use pnpm commands and configurations. This may involve modifying build scripts, test scripts, and deployment scripts.

Example: In the CI configuration file, replace npm or yarn commands with pnpm commands:

yaml
build:
  script:
    - pnpm install
    - pnpm run build

Step 5: Validate and Test the Migration

After completing the above steps, conduct comprehensive testing to ensure all packages can correctly install dependencies, build, and run. This may include unit tests, integration tests, and end-to-end tests.

Example: Run pnpm commands to verify successful installation and build:

bash
pnpm install
pnpm run build

Step 6: Cleanup and Optimization After Migration

After migration, perform cleanup tasks such as removing unnecessary Lerna configuration files and optimizing new pnpm configurations.

By following these steps, you can successfully migrate from Lerna to pnpm, enhancing dependency management efficiency and optimizing the entire project's build and release process. This example should help you understand the specific steps and considerations involved in the migration.

Lerna is a tool used to manage JavaScript projects with multiple packages, which can optimize workflows that are difficult to handle using git and npm. However, LeRNA does not directly handle package dependencies, but rather needs to be used in conjunction with package managers such as NPM or Yarn.

Pnpm is a space saving package manager. It saves disk space through hard linking and symbolic linking, and can provide native support for multi package (monorepo) projects. This means that we can use only pnpm to achieve the same effect when using Lenna in combination with npm or yarn.

The migration from Lerna to pnpm can be roughly divided into the following steps:

1. Evaluate project requirements

Firstly, we should evaluate the existing LeRNA project structure and dependencies to determine if all functions can be found to be equivalently implemented in pnpm. This includes:

-Multi package version synchronization -Handling dependencies between packages -Release process -Custom Script

2. Install PNPM

Next, we need to install pnpm in the development environment, which can usually be done through the following command:

sh
npm install -g pnpm

3. Initialize PNPM workspace

Create a 'pnpm workspace. yaml' file using the following command, which will define the settings for the workspace:

sh
pnpm init

Then edit this file and add a configuration similar to the following, specifying the location of the package:

yaml
packages:
- 'packages/*'

4. Adjust the 'package. json' file

Add the workspace configuration for 'pnpm' to the 'package. json' file in the root directory of the project:

json
{
"private": true,
"workspaces": [
"packages/*"
]
}

5. Remove Lerna configuration

You can remove the configuration file 'lerna. json' for Lerna and ensure that the relevant Lerna commands are removed from the script section of 'package. json'.

6. Migration scripts and commands

If there are scripts that use Lenna for package management (such as Lenna bootstrap), these scripts need to be modified to the corresponding command of pnpm. For example, 'lerna bootstrap' can be replaced by 'pnpm install' because pnpm automatically links packages in the workspace.

7. test

After completing the configuration, it is necessary to thoroughly test the entire project to ensure that all dependencies are installed correctly, the script can run normally, and the CI/CD process is not affected.

8. Update documentation and continuous integration configuration

Don't forget to update the project documentation to reflect new build steps and commands, while ensuring that the CI/CD system uses pnpm to install dependencies and execute tasks.

Example

Suppose we have a project managed by LeRNA that includes two packages: 'package-a' and 'package-b', where 'package-b' depends on 'package-a'.

In Lenna, we may have a 'lerna. json' file in the root directory of the project, which contains the following content:

json
{
"packages": ["packages/*"],
"version": "independent"
}

We will also see similar 'scripts' in the' package. json 'file:

json
{
"scripts": {
"bootstrap": "lerna bootstrap",
"publish": "lerna publish"
}
}

After migrating to PNPM, we no longer need this' lerna. json 'file, but instead add workspace configuration in the' package. json 'root directory and update the script:

json
{
"private": true,
"workspaces": ["packages/*"],
"scripts": {
"install": "pnpm install",
"publish": "pnpm publish --filter ./packages/*"
}
}

In this way, we have completed the basic migration process from Lerna to pnpm. Of course, the migration of specific projects may be more complex, requiring gradual completion and ensuring that each step is executed correctly.