Last 3.4-beta.14 Release, Faster Builds, Smaller Bundles and Modern Setups with the Rspack integration ⚡

schlaegerz · October 28, 2025, 3:02pm

How so? Do you mean that any file inside the client or server folders, at any level in the file system, should automatically run only on the client or server? I haven’t used this pattern much and I’m not sure if it ever worked, but please share more details.

So in existing meteor if I run
meteor test --driver-package meteortesting:mocha --port 3050
Then it segregates the tests into client and server. Client being ones that require the browser to be able to run.
I believe it does this just by deciding that if a test is under any /client/ folder it is a client unit test, and if it is not it is a server unit test.

I don’t get this, what do you mean?

For our existing app we have two ways to run test, the above for unit tests and

meteor test --full-app --port 3005 --settings test.settings.json --driver-package meteortesting:mocha --exclude-archs web.browser.legacy

for functional tests.

In existing meteor the .spec files are only loaded for the functional tests, not the unit tests. Loading the specs for my unit tests was causing my meteor to crash with a memory error. Not exactly sure why, but there was too much being loaded in any case.

The other thing that is broken in my repo in my last message is that if you run the functional tests. It should run a mostly normal server instance along with a client instance. In old meteor on the server Meteor.isAppTest would be set to true, in the RSPack Meteor.isAppTest is being set to false, which breaks tests.

The dummy app in this package does the same thing

nachocodoner · October 28, 2025, 4:55pm

I followed the docs here:

What I understand is that for unit tests, meteor test eagerly loads both .spec[s] and .test[s] files, and that’s what I implemented.

Then for full app / functional tests, the pattern is *.app-test[s].* and *.app-spec[s].*. Isn’t this what you’re getting? Or is your result different from what the official docs describe? You stated that “In existing meteor .spec files are only loaded for the functional tests” but that seems only be achieved via unit testing according to docs.

About client/server specifics, you’re right, I didn’t cover all those edge cases when using eager loaded tests (testModule at package.json achieve it). I’ll look into solutions for that using the repositories you shared for eager tests.

Also, do you know if server/client tests only apply to the conventional server/client folders, or if they also affect files within imports or any other root folders with client or server folders within? Do you have tests described outside client/server folders?

schlaegerz · October 28, 2025, 8:58pm

Ah you are right about the spec, the problem was more about not loading anything that was outside of client/server folders.

For my unit tests it does seem that if it is not inside of a client or server folder it won’t load the test at all.
I tried today to find where this is specified anywhere in the meteor docs and I believe it is based on this behavior Application Structure | Meteor Guide

Now I agree this kind weird and probably not what we want the expected behavior to be, but I bet there are going to be a lot of apps that are structured like my mine and this should be either the default behavior or very easy to switch to.

The Meteor.isAppTest not being true is definitely a bug and should be resolved.

vikr00001 · October 28, 2025, 9:53pm

I’m trying to turn off rspack hot reloading for testing purposes. Here is my relevant rspack.config.js. I have temporarily removed Meteor package hot-module-replacement as well. But, the client console logs show HMR is still being loaded. What am I missing?

rspack.config.js

        devServer: {
            allowedHosts: 'all',

            hot: false,
            liveReload: false,
            webSocketServer: false,

            client: {
                overlay: false,
            },
        },
        devtool: Meteor.isDevelopment ? 'eval-source-map' : false,
    };

My client console logs show HMR is still being loaded:

Client Console log

[webpack-dev-server] Server started: Hot Module Replacement enabled, Live Reloading enabled, Progress disabled, Overlay disabled.
log.js:39 [HMR] Waiting for update signal from WDS...

vikr00001 · October 29, 2025, 1:05am

@nachocodoner , please ignore my post about disabling HMR. It’s accurate but the only reason I was trying it was to rule out a variable involved in connecting rspack HMR to Cloudflare. I’m pretty sure now that HMR is part of an anomaly I’m encountering, and I do want it, so I’m turning it back on.

nachocodoner · October 30, 2025, 3:47pm

Rspack 1.6.0 is now available. If you’re using Meteor 3.4-beta.12, you can already upgrade Rspack to version 1.6.0.

The Meteor-Rspack integration is loosely coupled, so you no longer need to wait for Meteor updates to use newer Rspack versions. Meteor only defines a minimum verified version, meaning it’s the version we’ve tested and confirmed to work reliably with Meteor. You’re free to upgrade to newer versions at your app’s package.json on your own responsibility, without waiting for Meteor to bump that minimum. Rspack’s minor versions rarely introduce breaking changes, so you can safely benefit from newer releases whenever you decide.

That said, in the upcoming 3.4-beta.13, we’ll raise the minimum verified Rspack version to 1.6.0, ensuring it works smoothly.

Highlights of Rspack 1.6.0:

Improved tree-shaking for dynamic imports, allowing more cases to benefit from reduced bundle sizes.
Support for import defer. I was following this proposal closely and it’s great to see it supported in Rspack already. For context, import defer works similarly to Meteor’s old “nested imports”, deferring module evaluation (and its dependency subtree) until the module is actually used. This helps reduce initialization costs and improve performance. I’ll update the docs to cover this.
Fix for a persistent cache issue reported by the Meteor community. Those who experienced caching problems should see improvements in this release. Please keep sharing your issues with the wider open-source communities, even those outside Meteor, they seem to listen.
- Related issue: rspack#11804

Let me know your experience with Rspack 1.6.0 if you test it early.

harry97 · October 31, 2025, 9:07am

The Meteor-Rspack integration is loosely coupled, so you no longer need to wait for Meteor updates to use newer Rspack versions.

Looks like someone learned their lesson from Cordova design.

Meteor only defines a minimum verified version, meaning it’s the version we’ve tested and confirmed to work reliably with Meteor. You’re free to upgrade to newer versions at your app’s package.json on your own responsibility, without waiting for Meteor to bump that minimum. Rspack’s major versions rarely introduce breaking changes, so you can safely benefit from newer releases whenever you decide.

awatson1978 · October 31, 2025, 3:16pm

@nachocodoner

Hoss, you are the GOAT.

Your RSPack upgrade got the Cornerstone3D viewer working; the GPU optimizations working; the webworkers working; the WASM modules working.

DUDE. Phenomenal work. Maybe the most significant upgrade to the stack since Meteor 0.6.4. I mean, this is easily a 4.0 release, as far as I’m concerned.

And that’s not even talking about it being like 2x faster to compile.

There were some hiccups that are typical of a beta release… hot-module loading hiccups that need the occasional meteor reset; Material UI styling broke; behavior of React hooks in the Atmosphere packages changed; and no more static linking from packages/* into the parent app. But Claude and I were able to pass hooks and schemas and other objects through the Meteor object into the Atmosphere packages, and once we settled on that pattern, everything fell into place.

Phenomenal work. Can’t thank you enough for this upgrade.

awatson1978 · November 1, 2025, 5:18pm

Womp, womp.

Different project, hitting a file size error again. RSPack is allowing us to use the most-modern libraries and web features (web workers, GPU optimization, WASM, etc.), and I think there’s a tendency for some of them to have larger binary dependencies for some of the advanced browser features. For whatever reason, IPFS and Cornerstone both maxed out the hosting limits.

Which is a little frustrating, in so far as Galaxy does let us choose the option of container size; yet the uploader seems to be capped at a tiny size.

Any possibility of a meteor deploy --size medium command? My dream deployment/dev-ops scenario would be running something like:

meteor deploy --size medium --settings packages/nifty-workflow/configs/settings.json --extra-packages 'myorg:nifty-workflow' nifty-workflow.meteorapp.com

harry97 · November 2, 2025, 8:33am

@philippeoliveira Galaxy folks?

ceigey · November 2, 2025, 9:27am

Oh, I didn’t know about @swc/helpers… To be honest, reading the description in their docs, I’m not 100% sure what it does (maybe I need a second look when less tired). But I do recall at one point having similar issues to what you described before the 3.4 beta, which went away, but maybe I should look into this now.

This is what I’m using on the Vite side:

import { meteor } from 'meteor-vite/plugin'
import vue from '@vitejs/plugin-vue'
import { vuetify } from 'vite-plugin-vuetify'
import UnpluginFonts from 'unplugin-fonts/vite'
// ^ for some reason, they use unplugin, but don't support Webpack, apparently?
import swc from 'unplugin-swc'
import { analyser } from 'vite-bundle-analyzer'
// ^ this one's new, probably irrelevant

My own thoughts so far:

I think I could possibly replace UnpluginFonts with @fontsource-variable/* packages (see here for an exmaple installation: Roboto | Install | Fontsource).
I think I can also use the Vuetify Webpack plugin.
Vue as an SPA should be trivial with SWC.

To be honest, I’ve got a foot in the Meteor world, a foot in the Nuxt/Nitro world, and both hands in the Python world (it’s a mental game of Twister for me), so I don’t know if I will be doubling down on Meteor, following Vite to the Nitro world (I’m a big fan of Nitro + H3, and Nuxt UI), or expanding the role of Python in our stack.

My ideal world where Meteor – as a runtime framework with an accounts system – is just a WinterTC compatible app I can hook into something like Nitro, and voila, Meteor deployed on AWS Lambda (or maybe a hypothetical Galaxy Functions ~~running on Deno/Bun~~, if I may plant the seeds of chaos…). But the specific subset of Meteor I currently use is narrow enough for that to make sense, I know that there’s a lot of people who rely on Meteor as a full stack framework + build system.

(But maybe with time the coupling will be loose enough that it’ll all just fall into place)

awatson1978 · November 2, 2025, 4:02pm

Also…. lower priority, but a biggish enough item to separate v3.4 from version 4.0:

Repack doesn’t completely handle the Atmosphere build pipeline for packages/*

I tried to install Cornerstone3D in packages/dicom, so it could be enabled as an optional module, but that did not work. Web workers weren’t registered, codexes couldn’t be accessed, etc. Eventually had to install Cornerstone in the main app, and implement ad-hoc tree-shaking if DICOM support isn’t needed.

nachocodoner · November 3, 2025, 10:33am

Thank you very much. I’m glad to hear the upgrade meets the goals behind the work: improving build times, reducing bundle size, and staying flexible enough to support any modern setup and configuration.

It’s a relief to see this effort paying off for each of you. I appreciate the support and feedback, and especially the patience and trust. This kind of upgrade has many edges to consider, and the commitment is to keep iterating and make sure it serves everyone well.

But Claude and I were able to pass hooks and schemas and other objects through the Meteor object into the Atmosphere packages, and once we settled on that pattern, everything fell into place.

Repack doesn’t completely handle the Atmosphere build pipeline for packages/*

I tried to install Cornerstone3D in packages/dicom, so it could be enabled as an optional module, but that did not work. Web workers weren’t registered, codexes couldn’t be accessed, etc. Eventually had to install Cornerstone in the main app, and implement ad-hoc tree-shaking if DICOM support isn’t needed.

Mainly, the reason is that Meteor packages use their own pipeline to keep the Rspack integration simple and reliable. While deeper Rspack integration in Meteor packages would be nice, I recommend moving to npm packages to gain the benefits of today’s standard, feature-ready Node/Web packaging.

I think part of the positive experience with the Rspack upgrade comes from delegating to a modern, faster bundler in Meteor 3.4. That shift follows a modern-first mindset, embracing established workflows. The same applies to moving app Atmosphere packages to npm to unlock these benefits.

With npm packages, it’s easy to bring them into the Rspack pipeline and ensure everything is registered and configured as expected, just like at app level. You also get npm ecosystem gains like caching and local management tools (linking, workspaces, lerna, pnpm, etc.). Every meteor/* import in your npm packages will still resolve externally, and Meteor will inject them properly. Besides, you avoid passing anything to the Meteor property for cross-package communication as you suggested to do before, everything is managed from the same common NPM ecosystem.

In my apps, I use a lerna setup with npm packages under ./packages. My Rspack config forces those packages to be compiled by Rspack because they use modern syntax, so that I don’t need to create distributable versions myself (see Meteor.compileWithRspack, where you can pass a package name or a regex for all your branded packages). It’s like keeping packages at the Atmosphere level, but with the extra features the npm ecosystem offers.

With this, your Meteor app moves to a more standardized and portable setup. Atmosphere packages remain for Meteor core needs, existing community packages, or cases that must hook into the Meteor bundler (addFiles, assets management, and other specifics).

So, regarding your suggestion: it’s worth considering and we will do, but I prefer to prioritize on modern-first solutions, and keep backward-compatibility paths simple. We can explore improvements for Atmosphere packages, but that tends to add complexity (I’ve tried before hardly) and keeps the community tied to older paths instead of adopting newer ones across the framework and JS standards. We’ve been living with Meteor-specifics for a long time, even promoting their expansion in previous directions, which kept us distant from the wider ecosystem. I hope by embracing the new, it can change that, as we’re already seeing with the latest upgrades.

nachocodoner · November 3, 2025, 10:59am

I’ll pass a note to the Galaxy team about your suggestions.

From the OSS side, what I can say is that the upcoming Meteor 3.4-beta.13 will include long-requested optimizations in the Meteor bundler and in how Atmosphere packages and their attached npm dependencies are added to production bundles.

For a long time, we’ve had related issues reported on GitHub and the forums, remaining idle for quite some time. As part of Meteor 3.4, we’re not only focusing on the new Rspack tool, but also revisiting the Meteor bundler to ensure we deliver quick improvements to the experience we all know and optimize it further. So even though Rspack already provides smaller bundles, Meteor’s Atmosphere packages will now contribute to reducing the final bundle size as well.

Meteor 3.4 introduces two new features for Atmosphere packages:

The ability to mark packages as devOnly, so they’re completely removed from production builds.
A new Npm.devDepends field to define dev dependencies, ensuring only the necessary node modules for development are included during dev time and excluded from production (meteor build).

We’ve marked several core packages as dev-only (babel-compiler, typescript, minifiers, and others), which previously added unnecessary size (noted further after the new SWC integration). This also opens the door to fixing bundle size issues in packages that should use dev dependencies, such as reywood:publish-composite and eslint, once their authors update them for Meteor 3.4 and adopt Npm.devDepends, along with any other upcoming revisions in both core and community packages.

As you can see in the picture below, the final bundle size produced by meteor build will be smaller, meaning your Galaxy deployment will take up less space. For example:

This is about Atmosphere package size, but it’s also an important note and a useful tip:

If any NPM dependency you’ve added in your app’s package.json is used only for development (for example, loaders and similar tools you may have added after adopting Rspack, or tools like eslint or monorepo), make sure they are listed under devDependencies. Review everything under dependencies and move any dev-only packages to devDependencies, this can significantly reduce your production bundle size. Of course, if some are part of your app’s runtime functionality, leave them there, but it’s worth double-checking. I’ve seen this often in real projects, where production bundles end up unnecessarily heavier because of this.

awatson1978 · November 4, 2025, 12:37am

I get the reasoning for unwinding dependency on Atmosphere, and was around for the original angst and community arguments when NPM pulled the rug out from under Atmosphere’s value proposition. Since then, I’ve found Atmosphere packages to retain some value for workflow modularization. But I’m not wedded to Atmosphere, could be convinced to migrate to NPM. I think the bigger question at this time is the NPM build pipeline and package publishing.

A ‘meteor rollup’ command would go a long way to paving the way to migrating off of Atmosphere.

nachocodoner · November 5, 2025, 8:22am

This does happen (Meteor.isAppTest === true), but only when running meteor test --full-app, which is the only context where it’s expected according to docs. Are you running in that mode?

Ah you are right about the spec, the problem was more about not loading anything that was outside of client/server folders.

I agree that eager testing based on the client and server folders is missing. I’ll try to implement it.

Edit: Ok, I am checking your repository deeply, and I see the scenarios where it doesn’t, not sure why. But, is a confirmation that those tests you added there is what Meteor 3 bundler would do, right?

Update: Good progress so far. I’ll treat this as the final effort to ensure backward compatibility for eager tests in Meteor 3.4. We’re close to the official release, and I prefer not to add more changes now. Any additional updates (non-critical) will be handled in the Meteor 3.4.x series.

schlaegerz · November 5, 2025, 5:42pm

Ok yeah I updated my repo to something that was absolutely passing tests in Meteor 3 bundler.

Looks like you got the isAppTest thing working, but my understanding is there are 2 maybe 3 contexts, and isAppTest was only being set in one (the client) and needed to also be set in the server.

The unit test split I can work around if there is a new standard, but definitely need some way to separate client from server unit tests, and to me the simplest is to just mimic meteor 3 and base it on the folder they are under.

My understanding is there should only be one set of APP tests running, its unit tests that have both.

nachocodoner · November 6, 2025, 12:59pm

I think I have the fix for both scenarios: unit tests and full-app functional tests, with all the missing behaviors discussed. I need to add your tests to the modern suite so we can track coverage in Meteor core. I’ll also verify nothing else broke while adding the eager-testing specifics.

Thank you for the reproductions. They make it easier to move fast, and you always share repos with clear paths to the issues.

Only issue I found was with mySpec.spec.ts at the project root. It tries to import something that doesn’t exist at that level. I assume this was a mistake, so I ignored the file. Please confirm it wasn’t meant to do something else.

filipenevola · November 6, 2025, 1:23pm

Hey, sharing some news here.

In a simple project, I’m able to use rspack locally and also build it with Docker. But I’m still facing issues with the public assets - they seem to be missing in the final bundle. You can see the logo not loading here https://binge-staging-2-codeftw.svc-us5.zcloud.ws/ (with rspack) but ok here https://binge.quave.dev (no rspack).

I didn’t have time to investigate the root cause to be honest, but @nachocodoner has access to the private repo.

Here is the Dockerfile I’m using currently:

FROM zcloudws/meteor-build:3.4-beta.12 as builder

WORKDIR /build/source
USER root

# Ensure Node.js is available in /usr/bin for rspack builds
# Some npm scripts use #!/usr/bin/env node and need node in PATH
RUN if ! command -v node >/dev/null 2>&1 || [ ! -f /usr/bin/node ]; then \
      NODE_PATH=$(command -v node 2>/dev/null || find /usr/local /home/zcloud/.meteor -name node -type f -executable 2>/dev/null | head -1) && \
      if [ -n "$NODE_PATH" ] && [ -f "$NODE_PATH" ]; then \
        mkdir -p /usr/bin && \
        ln -sf "$NODE_PATH" /usr/bin/node; \
      fi; \
    fi && \
    if ! command -v npm >/dev/null 2>&1 || [ ! -f /usr/bin/npm ]; then \
      NPM_PATH=$(command -v npm 2>/dev/null || find /usr/local /home/zcloud/.meteor -name npm -type f -executable 2>/dev/null | head -1) && \
      if [ -n "$NPM_PATH" ] && [ -f "$NPM_PATH" ]; then \
        mkdir -p /usr/bin && \
        ln -sf "$NPM_PATH" /usr/bin/npm; \
      fi; \
    fi

RUN chown zcloud:zcloud -R /build

USER zcloud
COPY --chown=zcloud:zcloud . /build/source

ENV METEOR_DISABLE_OPTIMISTIC_CACHING=1
# Ensure PATH includes /usr/bin where we symlinked node
ENV PATH="/usr/bin:/usr/local/bin:${PATH}"

# Install dependencies with optional dependencies (needed for rspack native bindings)
# Clean install approach to avoid npm optional dependency bugs
# The issue is that npm sometimes fails to install optional dependencies for native bindings
# We'll detect the platform and explicitly install the correct binding
# Normalize architecture: x86_64 -> x64, aarch64 -> arm64
RUN rm -rf node_modules package-lock.json && \
    meteor npm --no-audit --no-fund install && \
    ARCH=$(uname -m | sed 's/x86_64/x64/; s/aarch64/arm64/') && \
    PLATFORM="linux-${ARCH}-gnu" && \
    (meteor npm --no-audit --no-fund install "@rspack/binding-${PLATFORM}" 2>/dev/null || \
     meteor npm --no-audit --no-fund install "@rspack/binding-linux-x64-gnu" 2>/dev/null || true) && \
    meteor build --platforms web.browser --directory ../app-build

FROM zcloudws/meteor-node-mongodb-runtime:3.4-beta.12-with-tools
COPY --from=builder /build/app-build/bundle /home/zcloud/app

RUN cd /home/zcloud/app/programs/server && chmod +rw npm-shrinkwrap.json && npm --no-audit install

WORKDIR /home/zcloud/app

ENTRYPOINT ["/scripts/startup.sh"]

There are probably a lot of unnecessary commands there, but I want to make it work first and then optimize it.

Also, we’ve updated our base image, so an issue with node not being recognized outside Meteor should be fixed in the base image and not need these PATH fixes anymore in this Dockerfile.

Great progress overall, Nacho and team. It seems we’re getting closer and closer to a final fully working version

Our customers at Quave Cloud and Quave Services are excited with these updates.

filipenevola · November 9, 2025, 2:25pm

Hey, good news, our assets are working fine after adding this to rspack.config.js

plugins: [
    // Copy all static assets from public folder to ensure they're included in the build
    // This is necessary for PWA files (sw.js, manifest.json), images, and other static assets
    new rspack.CopyRspackPlugin({
        patterns: [
            {
                from: 'public',
                to: '.',
                noErrorOnMissing: true,
            },
        ],
    }),
],

I think this should work by default as this is Meteor default behavior, let us see what @nachocodoner has to tell.

Our Dockerfile is also simple again, before it was missing Node.js on the PATH but now it’s fixed on our base image.

FROM zcloudws/meteor-build:3.4-beta.12 as builder

WORKDIR /build/source
USER root

RUN chown zcloud:zcloud -R /build

USER zcloud
COPY --chown=zcloud:zcloud . /build/source

RUN meteor npm i --no-audit  && meteor build --directory ../app-build

FROM zcloudws/meteor-node-mongodb-runtime:3.4-beta.12-with-tools

COPY --from=builder /build/app-build/bundle /home/zcloud/app

RUN cd /home/zcloud/app/programs/server && npm i --no-audit

WORKDIR /home/zcloud/app

ENTRYPOINT ["/scripts/startup.sh"]

Staging: https://staging-binge.quave.dev/
Prod: https://binge.quave.dev/