Monorepo tooling

Last week I found this open issue from telescope that peeked my interest. The issue is about improving the monorepo tooling that is used.

Telescope is considered a monorepo because it holds many different projects (in this case "microservices") inside one single repository.

Each microservice has its own package.json file with dependencies that need to be installed and when we install them all, we end up with many duplicates that take up unnecessary space on disk. We can see a list of all of telescope's dependencies here.

Looking for solutions

There are different tools to help solve this problem and in this blog post I am going to look at two:

• npm Workspaces
• pnpm

NPM Workspaces

npm v7 introduced Workspaces: a way to manage multiple packages in a monorepo all from the root directory.

To set it up we need to add this to the package.json file in the root of our project:

  "workspaces": [
    "workspace-1",
    "workspace-2"
  ]

Now when we run npm install, NPM is going to look inside each specified workspace and install the required dependencies.
If possible, the dependencies will be installed in the root node_modules folder and then symlinked to the workspace node_modules folder to avoid duplicates.

PNPM

pnpm stands for performant npm and it is in many ways faster than the regular npm. After installing all the dependencies it also uses less space on the disk.

The docs have a great explanation on how pnpm accomplishes this:

1. If you depend on different versions of the dependency, only the files that differ are added to the store. For instance, if it has 100 files, and a new version has a change in only one of those files, pnpm update will only add 1 new file to the store, instead of cloning the entire dependency just for the singular change.

2. All the files are saved in a single place on the disk. When packages are installed, their files are hard-linked from that single place, consuming no additional disk space. This allows you to share dependencies of the same version across projects.

pnpm can be installed with:

npm install -g pnpm

Of course it also supports monorepos. To specify workspaces we can create a pnpm-workspace_yaml file with inside:

packages:
  - 'workspace-1'
  - 'workspace-2'

Pros and Cons

✅ pnpm is faster and uses less disk space once all dependencies have been installed.

❌ The negative aspect is that it is a new package manager for the user to install and learn how to use.

✅ npm has the advantage of coming bundled with Node, so it is the predominant package manager.

❌ npm, even with its Workspaces improvements, is slower and takes more disk space than pnpm.

I have started looking at how to move the Telescope project from using npm to pnpm. I think that if pnpm is not a viable option, npm Workspaces is a good alternative to improve the current way we are doing things.

I will post updates with following blog posts on how this project unfolds!