feat(next/build): add prebuild and postbuild hooks

[ctjlewis]

Describe the feature you'd like to request

A user on StackOverflow wants to generate some code from his source files before the dev build begins. This is a request to add a feature for providing next/build with prebuild and postbuild hooks.

It is pretty common for other build tools to offer prebuild/postbuild hooks, and I imagine it would be relatively easy to plug into the underlying Webpack logic. In effect this is really just two await calls sandwiched around the existing build and should be relatively high benefit-to-cost ratio to implement.

Describe the solution you'd like

The simplest solution is just to add config options:

// next.config.js
{
  buildHooks: {
    preBuild: async () => { /* ... */ },
    postBuild: async () => { /* ... */ },
  },
}

And in next/build/index.ts:

export default async function build(
  dir: string,
  conf = null,
  reactProductionProfiling = false,
  debugOutput = false,
  runLint = true
): Promise<void> {
  try {
    /* ... */
    const buildResult = await nextBuildSpan.traceAsyncFn(async () => {
      /* Existing dotenv, config, etc. setup */

      await config.buildHooks.preBuild();
      /* Existing build logic */
      await config.buildHooks.postBuild();
    });
  } catch { /* ... */ }
}

Describe alternatives you've considered

Very limited semi-workaround:

You can use nodemon or something similar to listen to .next/server/pages/** and do something after the build script, or listen to src/pages/** and do something at the same time as the dev rebuild, but you cannot get in front of it.

[CalebBarnes]

This would be amazing.

[tatethurston]

I'd love this for https://github.com/tatethurston/nextjs-routes

[Nexuist]

This would be very useful for building next plugins, i.e. custom linting and AST transforming.

[theoephraim]

I'd recommend taking a look at astro for an example of a very flexible plugin system - see https://docs.astro.build/en/reference/integrations-reference/

The lack of flexibility with next makes it very difficult to build extensions that enhance the next.js core.

[usulpro]

Hey everyone! Would love to have this feature, what is the status now?

[staticshock]

This would also be useful for firebase deployments (at least in their current state.) firebase-tools is their [fairly inflexible] CLI that calls next build under the hood when deploying Next.js via Firebase Hosting. The tooling has a number of limitations, and Next.js build hooks, if they existed, would have allowed me to counter some of those limitations.

[techdragon]

Its kind of crazy this isnt already built in... I found it extremely surprising.

[ValentinGurkov]

Would love to see that as well