db.server.ts

import { PrismaClient } from "@prisma/client";
import invariant from "tiny-invariant";

import { singleton } from "./singleton.server";

// Hard-code a unique key, so we can look up the client when this module gets re-imported
const prisma = singleton("prisma", getPrismaClient);

function getPrismaClient() {
  const { DATABASE_URL } = process.env;
  invariant(typeof DATABASE_URL === "string", "DATABASE_URL env var not set");

  const databaseUrl = new URL(DATABASE_URL);

  const isLocalHost = databaseUrl.hostname === "localhost";

  const PRIMARY_REGION = isLocalHost ? null : process.env.PRIMARY_REGION;
  const FLY_REGION = isLocalHost ? null : process.env.FLY_REGION;

  const isReadReplicaRegion = !PRIMARY_REGION || PRIMARY_REGION === FLY_REGION;

  if (!isLocalHost) {
    if (databaseUrl.host.endsWith(".internal")) {
      databaseUrl.host = `${FLY_REGION}.${databaseUrl.host}`;
    }

    if (!isReadReplicaRegion) {
      // 5433 is the read-replica port
      databaseUrl.port = "5433";
    }
  }

  console.log(`🔌 setting up prisma client to ${databaseUrl.host}`);
  // NOTE: during development if you change anything in this function, remember
  // that this only runs once per server restart and won't automatically be
  // re-run per request like everything else is. So if you need to change
  // something in this file, you'll need to manually restart the server.
  const client = new PrismaClient({
    datasources: {
      db: {
        url: databaseUrl.toString(),
      },
    },
  });
  // connect eagerly
  client.$connect();

  return client;
}

export { prisma };