Does bun support Nest now? Last I knew (which admittedly was a while ago), bun had some issues running Nest applications

It does! Our Node.js compatibility has come a long way in recent months, and more and more frameworks are working out of the box. Our recent support for Nest is the reason for my creating this PR.

Note that the command printed afternest new isbun run start which does not actually use Bun to run Nest. That's because Nest has a#!/usr/bin/env node shebang innest.ts, which Bun respects.

If you want to see Nestjs working with the Bun runtime, create a new project withnest new, then runbunx nest start.

$ bunx nest start[Nest] 9357  - 08/07/2023, 3:07:55 PM     LOG [NestFactory] Starting Nest application...[Nest] 9357  - 08/07/2023, 3:07:55 PM     LOG [InstanceLoader] AppModule dependencies initialized +5ms[Nest] 9357  - 08/07/2023, 3:07:55 PM     LOG [RoutesResolver] AppController {/}: +5ms[Nest] 9357  - 08/07/2023, 3:07:55 PM     LOG [RouterExplorer] Mapped {/, GET} route +1ms[Nest] 9357  - 08/07/2023, 3:07:55 PM     LOG [NestApplication] Nest application successfully started +1ms

Question, am I supposed to be able to see the output of the CI run? The test suite is passing for me locally.

I did give it a quick test with creating anest new project, building to js, and thenbun dist/main which indeed worked as expected, which is great! I'm working on testing it with a bit of a larger, more complex project to see if it's capable of working there, and if soI'd be happy to approve this 😄

As it turns out,my project uses a few packages that bun does not support yet (node's crypto package), but otherwise itseemed like everythingwould have worked

Awesome thanks Jay!

Those incompatibilities are called out in Bun's Node.js compat page:https://bun.sh/docs/runtime/nodejs-apis. By and large, Bun users aware of the fact they're using a pre-stable runtime. Needless to say, feel free to close any issues that are mistakenly opened in the Nest.js repo, but anecdotally Bun users usually know to blame Bun when they encounter Node.js compatibility issues. Happy to revert this if it increases your maintenance burden.

anecdotally Bun users usually know to blame Bun when they encounter Node.js compatibility issues when using Bun

I hope that this remains true. Speaking from my experience, we get a lot of issues aboutlibrary issues that Nest just wraps with small modules where the issue should be reported to the underlying module, so I'd be expecting to see issues show up either in GitHub or Discord, but we'll definitely direct them to the correct place 😄

@jmcdo29 Oops I made a mistake -bunxalso respects the shebang, sobunx nest start will still be using Node.js. You need to use the--bun flag to override the shebang there. There's some module resolution bug currently (looking into it now) but as you found, runningnest build first then runningdist/main.js directly seems to be working.

Fixed CI - forgot togit add files 🤦‍♂️

With#2228 landed this andnestjs/docs.nestjs.com#2820 should be good to merge

We're hoping to announce Nest.js support in an upcoming release blog post as well 👍

Excellent work! Thank you very much for these advances! This is great !

We had to revert#2228 due to#2247 (pnpm users)

@kamilmysliwiec Sorry about that. I could put in another PR to handle absolute paths there but we've since fixed this on the Bun side as well:oven-sh/bun#4113

Reverting that change does not affect Bun compatibility (for Bun v0.8+) and this PR remains mergeable.

So excited for this combination

Hey, just tried out bun v1.0 in one of my microservices but got an error.

Other problem ofBun is withConsole constructor. NestJs use it forLogger

@v1d3rm3 Nest doesn't use theConsole constructor, justprocess.stdout andprocess.stderr

fair enough!

so I guess we should merge this only after they resolve this issue on their side:oven-sh/bun#1641

Bun now supportsemitDecoratorMetadata as of1.0.3. I've tested this with the following:

nest new bun-test --skip-install -p npmcd bun-testbun installbun run src/main.ts<navigate to http://localhost:3000 in browser>

It now seems that the emitted metadata is indeed correctly there and working to allow Bun to be bother a package manager and a runtime environment for Nest.

Do be aware that there are somequirks with fastify, and pino, so it'stechnically only a partial support.

Hello@jmcdo29
Were you able to compare memory consumption?

With node a small project: ±150 mb
With bun the same project: ±420 mb

Didn't check for memory consumption, was more concerned if it worked in the first place

Hello@jmcdo29 Were you able to compare memory consumption?

With node a small project: ±150 mb With bun the same project: ±420 mb

You guys most probably saw thiscomment made by Jarred on the Bun project but in case you didn't...

Has anyone compared memory consumption? I see that the memory consumption is 3x more with bun
nestjs/nest-cli#2223 (comment)

We will prioritize reducing memory usage in a month or two. Our focus right now is fixing bugs that make stuff not work at all (like the above "uninitialized constant" issue)

Hi, what is this currently waiting for?@jmcdo29 It's not clear to me if this is waiting for someone/something to be done or it's ready to be merged now?

I tried to run smallest microservice on bun, but it gives errors, one of them I posted earlier.

@vnenkpet Bun as a package manager does indeed work with Nest. Bun as a runtimemostly works, but there are still quirks with pino and fastify,as I've already mentioned.If we are to merge this in right now,I would want to be incredibly clear in the prompt that this is for Bunthe package manager and not Bunthe runtime.

While (probably) most people who use Bun know to report errors to the Bun runtime repo, I have no doubt in my mind that we'd still get a good number of Bun related bugs that having nothing explicitly to do with Nest which would end up generating a lot of noise for us.

So for right now, I want to wait for Bun to stabilize a bit more. I want to know that we won't be getting issues for the Bun runtime in our repos, I want to know that we won't end up having an uptick in our Discord server for Bun support, and I want to know that Bun supports Nest with both Express and Fastify,and whatever logger people end up choosing to use (winston, bunyan, pino, ogma, etc).

If anyone wants to use Bun with Nest and see how it goes, great! Please do and support the ecosystem and the Bun community, but be aware that any bugs are not inherently on Nest to fix, and should be properly reported to the correct place.

It's worth noting that Bun currently has issues withnpm packages that require post-install scripts, such assharp. There's adraft PR to fix this, but this is just to warn that Bun as a package manager isn't necessarily smooth sailing quite yet.

It's worth noting that Bun currently has issues withnpm packages that require post-install scripts, such assharp. There's adraft PR to fix this, but this is just to warn that Bun as a package manager isn't necessarily smooth sailing quite yet.

This has partially been fixed herehttps://bun.sh/blog/bun-v1.0.17
The list of scripts that will run (includingsharp):https://github.com/oven-sh/bun/blob/main/src/install/default-trusted-dependencies.txt

@kamilmysliwiec what's blocking this PR from being merged?

I am using bun as a package manager (not as a runtime) for over a year now within all my projects and never had a single issue. Even the hosting providers I use (Vercel, Cloudflare, Render) all support Bun as a package manager. The PR is nearly a year old and is pretty straight forward. Can it be merged?@kamilmysliwiec

@MickL as soon as they'll be full Node - Bun parity and using Bun as a runtime is going to be fully safe, we'll merge this PR

Why is there a need to wait for the runtime? This PR is just about replacing the package manager, not the runtime.

Because it's quite likely that some people may think they can use Bun as a runtime too, if it's one of the suggested options in the CLI.

I dont think this will be the case. The CLI adds scripts that clearly use Nodenode dist/.... If someone would replace this withbun run dist/..., Bun would actually still run with the Node runtime if the scripts are marked with a shebang:

https://bun.sh/docs/cli/run#bun

Please merge it

Will it ever be merged?

We still waiting@Jarred-Sumner

If the requirement is for Bun to work with Nest.js as a runtime as well, is there a tracking issue on what specific problems there are with using Bun for Nest.js? I feel there's a lack of clarity here that makes it hard to understand what's actually missing or broken.

As I understand, NestJS doesn’t support ES6, so Bun is also not a viable option, is that correct?

#2223 (review)