Drizzle Postgres on Fly

Run Drizzle in a Fly.Service, with Fly Managed Postgres on the same organization’s private network. Start with Fly setup, the Service tutorial, and a src/schema.ts exporting Users from the Postgres client guide.

Install the database dependencies

pnpm add drizzle-orm@1.0.0-rc.5-ab785fc @effect/sql-pg pg
pnpm add -D drizzle-kit@1.0.0-rc.5-ab785fc

The Drizzle versions match the repository’s Effect integration.

Configure migration generation

drizzle.config.ts

import { defineConfig } from "drizzle-kit";

export default defineConfig({
  dialect: "postgresql",
  schema: "./src/schema.ts",
  out: "./drizzle",
  dbCredentials: { url: process.env.DATABASE_URL! },
});

DATABASE_URL is the direct Postgres URL used by the migration runner, not the pooled runtime URL.

Generate after changing the schema

pnpm exec drizzle-kit generate

Review the generated SQL and snapshots, including any rename decisions, before applying them.

Commit the migration

git add src/schema.ts drizzle.config.ts drizzle
git diff --cached

git commit -m "Add users migration"

Commit the schema, SQL, and snapshots together; CI deploys this reviewed history rather than generating it.

Declare the cluster

src/db.ts

import * as Fly from "alchemy/Fly";

export const Db = Fly.Postgres("Db", { region: "iad" });

This provisions a billed Managed Postgres cluster, not an unmanaged Postgres Machine.

Keep the driver outside the bundle

// src/api.ts — the Service from the tutorial
{
  app: Site,
  main: import.meta.url,
  region: "iad",
  build: { install: ["pg"] },
}

pg must be installed in the Service image because bundling its CommonJS exports breaks the driver’s interop.

Bind the cluster

import { Db } from "./db.ts";

Effect.gen(function* () {
  const conn = yield* Fly.ConnectPostgres(Db);
  return {
    fetch: Effect.succeed(HttpServerResponse.text("Hello from Fly!")),
  };
}),
}).pipe(Effect.provide(Fly.ConnectPostgresHttp)),

The binding attaches the cluster to the Service’s App and supplies pooled and direct connection Effects. These excerpts use the tutorial’s minimal text handler until the database is migrated.

Provision before the first migration

pnpm alchemy deploy

Keep the tutorial’s yield* Api and public IP in the Stack, using Fly.providers(). This first deployment creates the database and a handler that does not yet query application tables.

Apply the committed SQL

pnpm exec drizzle-kit migrate

Supply the cluster’s connectionUri as the migration runner’s secret DATABASE_URL, and run where the direct hostname resolves and is reachable on the Fly organization network, such as a correctly configured WireGuard peer or a Machine on 6PN. A pooled URI is not the migration endpoint.

Open the runtime client

import * as Drizzle from "alchemy/Drizzle/Postgres";

const conn = yield* Fly.ConnectPostgres(Db);
const db = yield* Drizzle.Postgres(conn.connectionString);

The pooled connection opens lazily when a request first queries the database.

Query from the Service

import { Users } from "./schema.ts";

return {
  fetch: Effect.succeed(HttpServerResponse.text("Hello from Fly!")),
  fetch: Effect.gen(function* () {
    const users = yield* db.select().from(Users).pipe(Effect.orDie);
    return yield* HttpServerResponse.json({ users });
  }),
};

Queries run inside the request scope, rather than during infrastructure construction.

Deploy the application

pnpm alchemy deploy

For subsequent schema changes, generate, review, and commit first, then apply the committed migrations before deploying compatible application code. alchemy deploy does not replace drizzle-kit migrate in this guide.

Choose one migration owner

Fly.Postgres also supports a migrations directory, but this guide deliberately leaves it unset and keeps Drizzle as the migration owner. Switching an existing database to Alchemy’s migration history is a separate migration adoption decision, not a command substitution.

Continue

See the Managed Postgres guide, portable Postgres queries, and migration workflow. The fly-postgres example demonstrates the Service binding, but its test-only HTTP migration endpoint is not used here.