Debugging Astro and Yarn Berry + nodeLinker pnpm

Published at October 19, 2023, 13:47 GMT+0
An image containing the text, "Debugging Astro and Yarn Berry with nodeLinker pnpm".
An image containing the text, "Debugging Astro and Yarn Berry with nodeLinker pnpm".

Hey, everyone! Hope you are all doing well, in this post, I’m going to do a quick share about my experiences in debugging stuff when I was building something with Astro and Yarn Berry (with `nodeLinker: pnpm`).

What, I thought pnpm is a similar tool to npm and Yarn?

Yes, that is true, from a perspective. However, Yarn happens to have this thing called nodeLinker. There are 3 values available for this config:

  1. `node-modules`, which is the default one (used in Yarn Classic and npm).
  2. `pnp`, which is a mode where we don’t use `node_modules`. Instead, there are two files called `.pnp.cjs` and `.pnp.loader.mjs`. An example can be seen in this astro-yarn-berry-pnp repository. To have the best development experience, we are required to set up Editor SDKs.
  3. `pnpm`, which is a somewhat middle ground between `node-modules` and `pnp`. While `pnp` completely “flattens” the dependency structure and `node-modules` mode has a chance for hoisting issues, `pnpm` can be seen as the best of both worlds. It still creates a `node_modules` folder, but it uses symlinks so that the packages and dependencies can find each other.

The issue: using Astro with React Integration

I have prepared this sandbox here, containing a setup of a broken Astro with React integration. The error is as follows:

error Cannot find package 'vite' imported from /workspaces/workspace/node_modules/.store/@vitejs-plugin-react-virtual-8d8f5dfd7e/node_modules/@vitejs/plugin-react/dist/index.mjs
Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'vite' imported from /workspaces/workspace/node_modules/.store/@vitejs-plugin-react-virtual-8d8f5dfd7e/node_modules/@vitejs/plugin-react/dist/index.mjs
at new NodeError (node:internal/errors:405:5)
at packageResolve (node:internal/modules/esm/resolve:782:9)
at moduleResolve (node:internal/modules/esm/resolve:831:20)
at defaultResolve (node:internal/modules/esm/resolve:1036:11)
at DefaultModuleLoader.resolve (node:internal/modules/esm/loader:251:12)
at DefaultModuleLoader.getModuleJob (node:internal/modules/esm/loader:140:32)

This happened right after I did `yarn astro add react`, which is exactly the command from the guide in the @astrojs/react documentation.

So, what exactly happens here?

From the error, we could see that somewhat the package `@vitejs/plugin-react` can’t find `vite`. Curious, right? Now let’s inspect the `package.json` of `@vitejs/plugin-react` deeper. Is the `vite` dependency not included in the `package.json`?

// ...
"dependencies": {
"@babel/core": "^7.22.20",
"@babel/plugin-transform-react-jsx-self": "^7.22.5",
"@babel/plugin-transform-react-jsx-source": "^7.22.5",
"@types/babel__core": "^7.20.2",
"react-refresh": "^0.14.0"
"peerDependencies": {
"vite": "^4.2.0"

OK, it seems like `vite` is defined in the `package.json`, but as `peerDependencies`. Now, what is `peerDependencies`? According to the npm documentation of peerDependencies, it is a field in `package.json` that specifies the list of dependencies that the “host project” should include.

Alright, with that in mind, we will ask, “Who installs this `@vitejs/plugin-react`?” Since this error only started happening after we installed `@astrojs/react`, we can be sure that it’s the culprit. So, let’s inspect the `package.json` of `@astrojs/react`.

// ...
"dependencies": {
"@vitejs/plugin-react": "^4.0.4",
"ultrahtml": "^1.3.0"
"devDependencies": {
"@types/react": "^18.2.21",
"@types/react-dom": "^18.2.7",
"chai": "^4.3.7",
"cheerio": "1.0.0-rc.12",
"react": "^18.1.0",
"react-dom": "^18.1.0",
"vite": "^4.4.9",
"astro": "3.2.3",
"astro-scripts": "0.0.14"

Okay, so it defines `@vitejs/plugin-react` as `dependencies` and `vite` as `devDependencies`. What does this mean? This means that, when we’re installing from the package registry (e.g. npm registry), it will install `@vitejs/plugin-react` and `ultrahtml`, but not others that are defined in `devDependencies`. This is because `dependencies` are “transitive” dependencies, which are installed at all times, whereas `devDependencies` will only be installed when we’re developing the package on our local machine.

So, that’s the answer to why `vite` is not defined, because we don’t install it.

So, is the solution simply just to install vite in our host project?

Yes, installing `vite` on the host project seems to do the trick, as could be seen in this sandbox, the Vite-related error doesn’t show up anymore. However, this seems to be fixed only if we’re working on a single-repo setup. What if we are using monorepo?

For monorepo, it’s more tricky. I have created a sandbox that reproduced the monorepo example. Here, we have a structure like the following:

├── astro
│ ├── ...
│ └── package.json
├── ...
└── yarnrc.yml

Now, the difference between the monorepo structure and single project structure is that, I think in monorepo there are some kind of hoisting issues that caused `@astrojs/react` to not be able to find `vite`, despite that we have installed `vite` inside the `astro` monorepo package. So now, what do we do? I found out that we might need to play around a configuration in `yarnrc.yml` called packageExtensions. Here’s what we’re adding:

vite: '*'

What do the above additions do? So, we have learned that `@astrojs/react` doesn’t have `vite` transitive dependency in it, right? And in this case, we have also installed `vite` in our `astro` monorepo package. So, what’s missing is that, the “bridge” between `@astrojs/react` and our `astro` monorepo package. We can implement that “bridging” by “patching” the `peerDependencies` of `@astrojs/react`. By adding `vite` into its `peerDependencies`, we tell `@astrojs/react` that, “Hey, the `vite` package is installed, but not here. It’s installed in the host project.”

And, voila! Now you will be able to run Astro without any errors, because `@vitejs/plugin-react` will ask `@astrojs/react` for `vite`, and `@astrojs/react` will ask the monorepo package `astro` for `vite`, which we have installed already as a `devDependencies`. This sandbox demonstrated the fix.


So, what do you do when you face dependency-related errors? Say, dependency A is missing.

  1. First, check if dependency A exists in the `package.json` of the dependency that requires it (say, dependency B).
  2. If dependency A exists in dependency B’s `package.json` and somehow it’s missing from `node_modules`, maybe it’s a good time to re-`yarn`.
  3. If dependency A exists in dependency B’s `package.json` but only as `peerDependencies`, ensure that our project has dependency A installed.
  4. If we have installed dependency A in our project but somehow we can’t still resolve the dependency, then we might need to “link” (or “patch”) dependency B’s `package.json` using `packageExtensions`.

Hopefully, that’s useful. Until next time and stay safe!