Should @babel presets need to be normal dependencies in order for assets:precompile to work?

[jennysharps]

We are working on moving to shakapacker from [email protected] and noticed that the installation instructions advise us to install the @babel/preset-env package--among others--as normal dependency instead of as a dev dependency.

In addition to @babel/preset-env, we also use @babel/preset-react & @babel/preset-typescript. Usually, all of these presets are installed as devDependencies as per https://babeljs.io/docs/en/babel-preset-env#install, for example. When we moved them to devDependencies, the assets:precompile step began to fail with the following in our CI pipeline:

[0mI, [2023-02-01T17:26:51.505750 <redacted>]  INFO -- : Compiling...
E, [2023-02-01T17:26:54.871106 <redacted>] ERROR -- : 
COMPILATION FAILED:
EXIT STATUS: pid 262 exit 1
OUTPUTS:
node:internal/process/promises:279
            triggerUncaughtException(err, true /* fromPromise */);
            ^

Error [ERR_MODULE_NOT_FOUND]: Cannot find package '@babel/preset-react' imported from /app/babel-virtual-resolve-base.js
    at new NodeError (/app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:2240:5)
    at packageResolve (/app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:2776:9)
    at moduleResolve (/app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:2804:18)
    at defaultResolve (/app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:2835:13)
    at /app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:2855:14
    at Generator.next (<anonymous>)
    at asyncGeneratorStep (/app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:45:103)
    at _next (/app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:46:194)
    at /app/node_modules/@babel/core/lib/vendor/import-meta-resolve.js:46:364
    at new Promise (<anonymous>) {
  code: 'ERR_MODULE_NOT_FOUND'
}

The command '/bin/sh -c CI=*****
Service 'rails-app' failed to build : Build failed

It works fine if we promote them to dependencies. Is this expected? Can anybody shed some light on this behavior?

[jennysharps]

I believe this was happening because we were running RAILS_ENV=production bundle exec rake assets:precompile. After moving the presets back to devDependencies and not setting RAILS_ENV at all when precompiling assets, the precompile step succeeds.

What is the intended way to precompile assets for production? Even when RAILS_ENV is set to production, I would've though a full install would still be required since dev dependencies are needed to build the bundle. An example is compiling typescript -- the @types packages are dev dependencies, but we need them in order to do type-checking when building the production bundle; we just don't need them to end up in the production bundle.

[jennysharps]

I believe the problem was multiple yarn installs happening during precompilation (still not sure why they installed production packages only 🤷‍♀️), and this seems to have fixed it https://forum.shakacode.com/t/how-to-skip-automatically-running-yarn-install-when-you-precompile/2417

[justin808]

@jennysharps I think the latest versions don't do the yarn installs at all. It's important to have your build process call yarn install to install the npm dependencies, just like the gems get installed.

Regarding production packages, many build environments run with the flag to skip the devDependencies. For example, that is the default behavior of Heroku's buildpacks.