feat(doc): create fly.io and ppg guide (#7338)

Co-authored-by: Arthur Gamby <arthurgamby@MacBook-Pro-de-Arthur.local>

Author: ArthurGamby

content/250-postgres/350-integrations/500-flyio.mdx

@@ -0,0 +1,146 @@
+---
+title: 'Fly.io'
+metaTitle: 'Deploy Prisma Postgres apps to Fly.io'
+metaDescription: 'Learn how to deploy applications using Prisma Postgres to Fly.io.'
+tocDepth: 3
+toc: true
+---
+
+[Fly.io](https://fly.io/) is a cloud application platform that lets you deploy full-stack applications globally. This guide shows you how to deploy a Node.js application using Prisma Postgres to Fly.io.
+
+## Prerequisites
+
+- A [Fly.io account](https://fly.io/docs/getting-started/launch/)
+- The [Fly CLI](https://fly.io/docs/flyctl/install/) installed
+- An existing application using [Prisma Postgres](/postgres) (see [Quickstart](/getting-started/prisma-postgres/quickstart/prisma-orm))
+
+## Deploy your application
+
+### 1. Generate Prisma Client in `postinstall`
+
+Ensure your `package.json` includes a `postinstall` script to generate Prisma Client during deployment:
+
+```json file=package.json
+{
+  // ...
+  "scripts": {
+    // ...
+    // add-next-line
+    "postinstall": "prisma generate"
+  }
+}
+```
+
+### 2. Launch your app with Fly.io
+
+From your project directory, run:
+
+```terminal
+fly launch
+```
+
+Follow the prompts to configure your application. Fly.io will auto-detect your Node.js application and create the necessary configuration.
+
+### 3. Set your database connection string
+
+Add your Prisma Postgres `DATABASE_URL` as a secret in Fly.io:
+
+```terminal
+fly secrets set DATABASE_URL="your-prisma-postgres-connection-string"
+```
+
+:::tip
+You can find your `DATABASE_URL` in your `.env` file or in the [Prisma Console](https://console.prisma.io).
+:::
+
+### 4. Deploy
+
+If not already deployed during `fly launch`, deploy your application:
+
+```terminal
+fly deploy
+```
+
+Once the deployment completes, you'll see a success message with your app's URL:
+
+```
+🎉  SUCCESS! Your app is live and ready to use!  🎉
+
+Visit: https://your-app-name.fly.dev/
+```
+
+:::note
+In the Fly.io dashboard, your app's status may show as "Pending" initially. It typically transitions to "Deployed" within a few minutes.
+:::
+
+## Additional considerations
+
+### Ensure your project uses the correct environment variable
+
+Ensure that the data source in your `prisma.config.ts` file is configured to use the `DATABASE_URL` environment variable:
+
+```ts file=prisma.config.ts
+import 'dotenv/config';
+import { defineConfig, env } from 'prisma/config';
+
+export default defineConfig({
+  datasource: {
+    url: env('DATABASE_URL'),
+  },
+  schema: './prisma/schema.prisma',
+});
+```
+
+### Running migrations in production
+
+To run migrations on your deployed Fly.io app, you can use:
+
+```terminal
+fly ssh console -C "npx prisma migrate deploy"
+```
+
+Or add a release command to your `fly.toml`:
+
+```toml file=fly.toml
+[deploy]
+  release_command = "npx prisma migrate deploy"
+```
+
+### Scaling and regions
+
+Fly.io lets you scale and place your application in [multiple regions](https://fly.io/docs/reference/regions/). For optimal performance, deploy your app in a region close to your Prisma Postgres database region.
+
+```terminal
+fly scale count 2 --region iad
+```
+
+## Troubleshooting
+
+### Prisma schema not found or Client not generated correctly
+
+If you're using a custom Dockerfile and your build fails because the Prisma Client cannot be found, it's likely due to one of two reasons:
+
+1. **Order of operations**: `npm install` (which runs `postinstall`) runs before the schema is copied.
+2. **Incorrect copy path**: The schema is copied to the root instead of the `prisma` folder.
+
+**Solution:** In your Dockerfile, copy the `prisma/` directory to `./prisma` **before** running `npm install`:
+
+```dockerfile
+# ❌ Wrong order or path
+COPY package*.json ./
+COPY prisma .                   # Copies contents to root (wrong structure)
+RUN npm install                 # postinstall runs but might fail or generate in wrong place
+
+# ✅ Correct order and path
+COPY package*.json ./
+COPY prisma ./prisma            # Copies to ./prisma folder (preserves structure)
+RUN npm install                 # postinstall finds schema in expected location
+COPY . .
+```
+
+## More information
+
+- [Fly.io Node.js documentation](https://fly.io/docs/languages-and-frameworks/node/)
+- [Fly.io Prisma documentation](https://fly.io/docs/js/prisma/)
+- [Prisma Postgres documentation](/postgres)
+