Prisma, SvelteKit and PlanetScale deployment issues on Vercel

Here’s some of the issues I faced when deploying a SvelteKit project using Prisma to Vercel.

I was following along with the awesome guide put together by Matia, on authentication with SvelteKit using cookies. By far the most comprehensive guide covering it with SvelteKit I have found. There’s also a video playlist covering it as well if you want to check that out.

If you’re just here for the “how’d you get it working on Vercel dammit??!1” then you can skip to the TL;DR. 😊

This isn’t a guide, more of a what I did along the way to getting this project deployed to Vercel. I’ll try to add as much information that I found useful along the way.

So after following Matia’s guide I wanted to deploy the finished project to test it out ‘in the wild’. So for that I needed to have a database to connect to.

Get a database to connect to

I did find a guide for how to set up a free PostgreSQL database on Heroku by Nikolas Burk in the Prisma documentation.

But I heard good things about PlanetScale so decided to give that a try. I followed along with the Prisma with PlanetScale quickstart.

The first thing I needed was the PlanetScale CLI, I’m a Windows Subsystem for Linux (WSL) user so needed to install the Linux version, this was a download from the releases page. I added to my home directory then run the command mentioned on the GitHub page:

sudo dpkg -i pscale_0.107.0_linux_amd64.deb

To get the file from my Windows downloads folder to my Linux home folder I used the explorer.exe command in WSL and dropped it in there:

cd ~
explorer.exe .

I followed the guide for setting up the database and skipped over the NextJS specific parts as I’ve already got the project in SvelteKit.

PlanetScale CLI commands

The bit’s to take away here are, create a database with the PlanetScale CLI:

pscale db create star-app --region eu-central

star-app is the name of the database and the region is the closest one to me here in the UK eu-central.

At the time of writing the available --region’s are:

AWS us-east-1 (Northern Virginia) - us-east
AWS us-west-2 (Oregon) - us-west
AWS eu-west-1 (Dublin) - eu-west
AWS ap-south-1 (Mumbai) - ap-south
AWS ap-southeast-1 (Singapore) - ap-southeast
AWS ap-northeast-1 (Tokyo) - ap-northeast
AWS eu-central-1 (Frankfurt) - eu-central
AWS ap-southeast-2 (Sydney) - aws-ap-southeast-2
AWS sa-east-1 (Sao Paulo) - aws-sa-east-1

Create a branch from the main branch to add the database changes to:

pscale branch create star-app initial-setup

Prisma schema config

As I mentioned earlier I already have an example project ready to go the one thing I needed to do was to update the Prisma schema file located in the root of the project (prisma/schema.prisma).

This can be initialized with this npx command npx prisma init, what you get is something like this:

generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

I needed to change "postgresql" to "mysql" and add in some additional items to the client and database (db):

generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["referentialIntegrity"]
}

datasource db {
  provider             = "mysql"
  url                  = env("DATABASE_URL")
  referentialIntegrity = "prisma"
}

model User {
  id           String   @id @default(uuid())
  username     String   @unique
  passwordHash String
  createdAt    DateTime @default(now())
  updatedAt    DateTime @default(now())
}

I’ve added the User model here that’s part of the SvelteKit project.

Now I’ll need add the local database connection string to a .env file:

DATABASE_URL='mysql://root@127.0.0.1:3309/star-app'

That’s local host on my machine 127.0.0.1 running on port 3309 with the database name star-app.

I can then use the PlanetScale CLI to proxy into the PlanetScale database:

pscale connect star-app initial-setup --port 3309

Now that I’ve got the database schema set up I can push these changes:

npx prisma db push

Because PlanetScale looks after all your changes there’s no need for prisma migrate.

I can add data locally with either the PlanetScale CLI or Prisma studio:

npx prisma studio

That’s it! My schema is now on PlanetScale ready to go into the main branch. I followed the guide to Create a deploy request from the PlanetScale guide.

Happy with PlanetScale

Overall I was super impressed with PlanetScale, I did spend the next couple of hours working through various issues with deployment after that though. More on that next!

Issues deploying

Ok so, this is where I spent the next few hours trying to work out why Vercel was giving me build errors.

So the first issue was because I was using bcrypt which causes a Vercel build error like this:

[vite-plugin-svelte-kit] Build failed with 3 errors:
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:43:28: ERROR: Could not resolve "mock-aws-s3"
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:76:22: ERROR: Could not resolve "aws-sdk"
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:112:23: ERROR: Could not resolve "nock"
> Build failed with 3 errors:
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:43:28: ERROR: Could not resolve "mock-aws-s3"
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:76:22: ERROR: Could not resolve "aws-sdk"
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:112:23: ERROR: Could not resolve "nock"
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:43:28: ERROR: Could not resolve "mock-aws-s3"
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:76:22: ERROR: Could not resolve "aws-sdk"
node_modules/@mapbox/node-pre-gyp/lib/util/s3_setup.js:112:23: ERROR: Could not resolve "nock"

Not much in there to tell you that it’s bcrypt but I found a StackOverflow question which mentioned it.

Switching out bcrypt with bcryptjs solved that part.

The next was a post install warning for @prisma/client the error looked like this:

.../node_modules/@prisma/client postinstall: warning In order to use "@prisma/client", please install Prisma CLI. You can install it with "npm add -D prisma".

So after digging around the Prisma examples I added a postinstall script and a prisma:generate to the package.json:

"scripts": {
  "vercel-build": "prisma generate && svelte-kit build",
  "prisma:generate": "prisma generate"
}

That built the project but looking at the preview shows that the serverless function has crashed:

This Serverless Function has crashed.

Your connection is working correctly.

Vercel is working correctly.

500: INTERNAL_SERVER_ERROR

Code: FUNCTION_INVOCATION_FAILED

So, it was at that point I sent the tweet mentioned earlier and I had @josefaidt come to the rescue with his blog post!

Scripts

So this is the secret sauce that got it working! These two scripts were what cleared it all up! This is what was in the post Josef shared.

"scripts": {
  "vercel-postbuild": "cp node_modules/@prisma/engines/*query* .vercel_build_output/functions/node/render/;cp prisma/schema.prisma .vercel_build_output/functions/node/render/",
  "vercel-build": "prisma generate && pnpm build && pnpm vercel-postbuild"
}

I replaced the vercel-build and prisma:generate scripts I was using with these two and the project built with no issues! 🥳

Massive thanks to @josefaidt for bringing this to may attention, which he in turn got from @mikenikles, sveltekit-prisma example 🙌

Massive thanks to both for this!

References

There’s been a lot of references mentioned, I’ve gathered them all up here if not mentioned already:

• https://joyofcode.xyz/sveltekit-authentication-using-cookies
• https://josef.dev/posts/svelte-kit-planetscale-and-prisma-on-vercel
• https://flaviocopes.com/prisma-fix-initialize-yet-vercel/
• https://stackoverflow.com/q/70097108/1138354
• https://vercel.com/support/articles/why-does-my-serverless-function-work-locally-but-not-when-deployed
• https://www.prisma.io/docs/guides/deployment/deployment-guides/deploying-to-vercel
• https://dev.to/prisma/how-to-setup-a-free-postgresql-database-on-heroku-1dc1
• https://docs.planetscale.com/tutorials/prisma-quickstart
• https://docs.planetscale.com/tutorials/deploy-to-vercel#deploy-to-vercel

Conclusion

I really like PlanetScale and Prisma! Two great tools to get you a database up and running super fast!

With Vercel this is the first time I have had an issue like this, and although the first set of error messages weren’t indicating that it was bcrypt I know for the future.