feat(@rspack-cli): make @rspack/dev-server and webpack-bundle-analyzer peer dependencies by Kocal · Pull Request #12682 · web-infra-dev/rspack

Kocal · 2026-01-08T13:44:42Z

Summary

Hi! 👋
This is my first PR here, do not hesitate to tell me if I didn't something wrong, thanks!

We are considering possibly replacing webpack by rspack in Webpack Encore
(a wrapper for webpack to make it easier to use in Symfony projects, existing for ~10 years now).

In Webpack Encore, we recently made webpack-dev-server an optional dependency (symfony/webpack-encore#1336), getting inspiration from e18e initiative. It allowed us to remove a tons of sub-dependencies and reduce the package size when not using some features.

But, when looking at @rspack/cli's npmgraph, I see it force to install ~225 dependencies (that's a lot!):

@rspack/dev-server is only useful when running rspack serve, and not all projects need it. Based on @rspack/dev-server's npmgraph, it brings ~207 dependencies,
webpack-bundle-analyzer is only useful when running rspack analyze, and not all projects need it. Based on webpack-bundle-analyzer's npmgraph, it brings ~16 dependencies

By making these two dependencies optional, we could reduce the number of dependencies to 2 (@discoveryjs/json-ext and webpack-bundle-analyzer).

It may be considered a breaking change, but it will only impact local development (not production builds), and only for people using rspack serve or rspack analyze.

WDYT? Thanks!

Checklist

~~[ ] Tests updated (or not required).~~
Documentation updated (or not required).

…r peer dependencies

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Kocal · 2026-01-08T13:46:29Z

packages/rspack-cli/package.json

+    "@rspack/core": {
+      "optional": false
+    },


@rspack/core was already a peerDependency but it was not explicitly configured as non-optional.

Copilot

Pull request overview

This PR converts @rspack/dev-server and webpack-bundle-analyzer from required dependencies to optional peer dependencies in @rspack/cli, reducing the default dependency count from ~225 to ~2. The change adds runtime checks in the serve and preview commands to verify @rspack/dev-server is installed before use, providing clear error messages when missing.

Key Changes

Moved @rspack/dev-server and webpack-bundle-analyzer from dependencies to optional peer dependencies
Added package availability checks with helpful error messages in serve and preview commands
Updated lockfile to reflect dependency changes

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 4 comments.

File	Description
packages/rspack-cli/package.json	Moved two packages to optional peer dependencies, added peerDependenciesMeta configuration
pnpm-lock.yaml	Updated to reflect packages moved from dependencies to devDependencies
packages/rspack-cli/src/commands/serve.ts	Added check for @rspack/dev-server availability before use
packages/rspack-cli/src/commands/preview.ts	Added check for @rspack/dev-server availability before use

Files not reviewed (1)

pnpm-lock.yaml: Language not supported

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Copilot · 2026-01-08T13:48:34Z

packages/rspack-cli/package.json

-    "@rspack/core": "^1.0.0-alpha || ^1.x"
+    "@rspack/core": "^1.0.0-alpha || ^1.x",
+    "@rspack/dev-server": "~1.1.5",
+    "webpack-bundle-analyzer": "4.10.2"


The version constraint for webpack-bundle-analyzer in peerDependencies uses an exact version (4.10.2) which is overly restrictive. Consider using a more flexible version range like "^4.10.2" to allow users to use newer compatible versions without peer dependency warnings. This follows the pattern used for @rspack/core which uses "^1.0.0-alpha || ^1.x".

Suggested change

"webpack-bundle-analyzer": "4.10.2"

"webpack-bundle-analyzer": "^4.10.2"

The previous contraint was fixed to 4.10.2, IMHO there is nothing to change here.

Copilot · 2026-01-08T13:48:34Z

packages/rspack-cli/src/commands/serve.ts

+        require.resolve(packageName);
+      } catch {
+        const logger = cli.getLogger();
+        logger.warn(


The error message uses logger.warn but then exits with code 2, which indicates an error. Consider using logger.error instead of logger.warn for consistency, since this is a fatal error that prevents the command from running.

Suggested change

logger.warn(

logger.error(

Copilot · 2026-01-08T13:48:35Z

packages/rspack-cli/src/commands/preview.ts

+        require.resolve(packageName);
+      } catch {
+        const logger = cli.getLogger();
+        logger.warn(


The error message uses logger.warn but then exits with code 2, which indicates an error. Consider using logger.error instead of logger.warn for consistency, since this is a fatal error that prevents the command from running.

Suggested change

logger.warn(

logger.error(

Copilot · 2026-01-08T13:48:35Z

packages/rspack-cli/package.json

+    "@rspack/core": {
+      "optional": false
+    },


Setting "optional": false for @rspack/core in peerDependenciesMeta is redundant, as peer dependencies are required by default. You can remove this entry and only keep the entries for optional peer dependencies (@rspack/dev-server and webpack-bundle-analyzer).

Suggested change

"@rspack/core": {

"optional": false

},

Kocal · 2026-01-08T14:00:36Z

I will apply Copilot comments after my work day

chenjiahan

Thanks for your contribution! It's great to hear that Webpack Encore is considering replacing webpack with Rspack.

For this PR, it introduces a breaking change for existing users, so we're unable to merge it into the main branch.

We plan to remove the webpack-bundle-analyzer in the v2 branch, see: #9270 (comment).

As for @rspack/dev-server, making it a peer dependency is something we could consider. However, the vast majority of users rely on the dev server, and turning it into a peer dependency would likely increase the burden of dependency management for users. That said, this is something we could revisit in the v2 timeframe.

codspeed-hq · 2026-01-08T14:38:43Z

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing Kocal:rspack-cli-peer-dependencies (7e42d29) with main (29642b2)}

Summary

✅ 16 untouched benchmarks
⏩ 1 skipped benchmark¹

1 benchmark was skipped, so the baseline result was used instead. If it was deleted from the codebase, click here and archive it to remove it from the performance reports. ↩

Kocal · 2026-01-08T15:19:50Z

Hi, and thanks for your response.

For this PR, it introduces a breaking change for existing users, so we're unable to merge it into the main branch.

That's fully understandable, no problem.

We plan to remove the webpack-bundle-analyzer in the v2 branch, see: #9270 (comment).

Good news! 🤩

As for @rspack/dev-server, making it a peer dependency is something we could consider. However, the vast majority of users rely on the dev server, and turning it into a peer dependency would likely increase the burden of dependency management for users. That said, this is something we could revisit in the v2 timeframe.

Yeah the dev-server is actually super useful, but only during developpment.

Depending on the project, assets are built during application deployment (git push and a service like Heroku, Netlify, Coolify, ... will pull and build your app).
At this point, only the rspack build command is useful and used. All dependencies installed via the installation of @rspack/dev-server have only increased deployment time and are taking up unnecessary disk space.

the vast majority of users rely on the dev server, and turning it into a peer dependency would likely increase the burden of dependency management for users

That's true, if the dev-server become a peerDependency, people will have to install it manually through:

pnpm add @rspack/core @rspack/cli @rspack/dev-server -D

# or if you plan to run `pnpm install --prod` for deployment
pnpm add @rspack/core @rspack/cli 
pnpm add @rspack/dev-server -D

I will add a new message on #9270.

Should we close this PR for the moment?

Kocal · 2026-01-08T15:26:11Z

Posted #9270 (comment)

I didn't try, but a workaround would be to configure packages resolutions and force @rspack/dev-server to be not installed in production.

This is easily doable with PNPM, if you are able to create this file before running pnpm install when deploying your app:

# pnpm-workspace.yaml
overrides:
  '@rspack/cli>@rspack/dev-server': link:node_modules/.ignored

chenjiahan · 2026-01-09T02:19:58Z

Posted #9270 (comment)

Thanks! I will discuss with the team to determine whether to make @rspack/dev-server a peer dependency.

Should we close this PR for the moment?

I will close this PR now. Thank you again for your contribution. ❤️

chenjiahan · 2026-01-16T03:36:22Z

Update:

webpack-bundle-analyzer has been removed in feat(cli)!: remove the built-in webpack-bundler-analyzer #12699
we plan to make @rspack/dev-server an optional peer dependency, see: feat!: make @rspack/dev-server an optional peer dependency #12750

Kocal · 2026-01-16T06:45:42Z

Oooh what a good news, thanks you @chenjiahan and @harpsealjs 😍

feat(@rspack-cli): make @rspack/dev-server and webpack-bundle-analyze…

7e42d29

…r peer dependencies

Copilot AI review requested due to automatic review settings January 8, 2026 13:44

Kocal requested a review from hardfist as a code owner January 8, 2026 13:44

github-actions bot added the release: feature release: feature related release(mr only) label Jan 8, 2026

Copilot started reviewing on behalf of Kocal January 8, 2026 13:45 View session

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Add support for Rspack symfony/webpack-encore#1389

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Kocal deleted the rspack-cli-peer-dependencies branch January 16, 2026 06:44

	"webpack-bundle-analyzer": "4.10.2"
	"webpack-bundle-analyzer": "^4.10.2"

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