Introduction

Monorepos are fantastic. They let you maintain all your projects in a single repository. I use one at my workplace and I see its advantages everyday. If you know anything about monorepos, setting them up can be tricky sometimes. Recently, I've been following the developments over at Turborepo, which attempts to make setting up the tooling for monorepose simpler. The more I look through their docs, the more I get exited about using it. So, I gave it a shot and I have to say, the experience has been fantastic.

Why this article?

If you're wondering you can just go to their docs and set it up yourself, yes, you absolutely can. They have a cli which can help you setup a new project and they have a solid set of examples for most scenarios. But, it is super fun setting things up from scratch, and I wanted to see how much of work it is with Turborepo.

The setup

I'll setting up a new monorepo with a couple of simple apps and a UI library which would be shared by the apps. The goal is not the design and functionalities of these apps, but the tooling and features Turborepo provides. There will be two apps admin and products, both of them will be bundled using Vite. Vite is blazing fast and you should definitely give it a try just for its speed. The UI library, which will contain just a button component, which is written in TypeScript, will be bundled using tsup. tsup uses esbuild underneath, so we can expect blazing fast build times. I'll be using yarn for package management. We will also be using a common eslint configuration which will be shared across all three codebases.

Let's get started!

Turborepo stuff

Let's first create a folder for our project and start initialising our monorepo.
As with any JS project, we start with a package.json.

package.json

This is the initial config I'm using. It has turbo and eslint installed as a devDependency. If you are familiar with monorepos, the workspaces array should make sense. All the projects in your monorepo should be listed as a workspace. Here, we have two directories, apps contain admin and products, and packages, which contains the UI library and the eslint configuration. Anything that can be shared across multiple projects can live in the packages folder.

Next is our turbo.json. This is Turborepo's config file. I browsed through their examples and found the simplest config to get started.

turbo.json

We'll be covering this in a later section.

Setting up apps

Vite has a cli which makes it easier for us to bootstrap a React app.
In our apps folder, run

yarn create vite admin --template react

This will create a new react app named admin. Similarly, we can create products app as well.

yarn create vite products --template react

Now we have two apps named admin and products in our apps directory.

Setting up the library

I've added all the dependencies needed for a TS library with types and eslint packages. Also added are the scripts for build, dev, lint.

packages/ui/package.json

Now, lets simply add a Button component and export it.

packages/ui/Button.tsx

packages/ui/index.tsx

Now, our project looks like this

Now that we have setup our apps and library, we can setup the tooling to link(turbocharge) them.

Add library as a dependency

The next step is to add the library as a dependency to our apps. It is as simple as adding it to devDependecies in both apps/admin/package.json and apps/products/package.json.

Turborepo will use the name field in the library's package.json to resolve it in the apps.

We can now use this Button component in admin and products.

In apps/admin/src/App.jsx

We can do the same thing in apps/products/src/App.jsx as well.

Adding scripts

The final step before we test this is to add scripts for build, lint and dev. In our root package.json, we can add

These commands are directly tied to the pipeline configurations in turbo.json. For example, if we look at the build command, with the "dependsOn": ["^build"], option, we are letting Turborepo know that build commands should only be run after all its dependencies are built. Turborepo is smart enough to realise admin has a dependency ui, which needs to be built before building admin. So, it builds ui first and then bundle admin. Pipelines are a powerful feature in Turborepo and you can read about it here.

Now, there is nothing left but to run our two apps. First, we would need to install our dependencies by running,

yarn install

Then, we start the dev server using

yarn dev

If we inspect the terminal messages, we can see that admin is running in localhost:3000 and products is running in localhost:3001.

(Look at the insane 2.914s start times! Vite FTW!)

Now if we navigate to localhost:3000, we see

We can see our button component is rendering as expected.

Setting up shared lint config

Similar to how we shared a library across apps, we can share config files across apps as well. We'll be using a single eslint config in all our apps and library. For that we shall create a folder called config in our packages directory.
Inside it, we'll create a file eslint-preset.js,

And a package.json.

packages/config/package.json

The package.json contains all the eslint packages we'll be needing, and notice the files property includes the lint config file.

Now, we add config as a dev dependency in admin, products and ui. In each of their package.json, add it as a devDependency

apps/admin/package.json

Also, we would need a .eslintrc.js which simply exports the lint config from config.

apps/admin/.eslintrc.js

Now, we we run yarn lint on our root folder, Turborepo will run the lint command on all of our projects.

Notice that we did not need to install eslint(except in the root) or its corresponding packages anywhere else other than the config folder.

Awesome! We have setup our own monorepo with two apps, a library and a shared eslint config.

Conclusion

This idea of monorepos can be extended and even backend code can be added to the same repo. One awesome use-case I can think of is sharing types between frontend and backend apps using a shared package. We have barely scratched the surface of Turborepo and its features. Remote Caching
is one such feature I'm exited to try out. Meanwhile, this exercise was a great starting point.

The source code for this can be found here

Cheers!