Remix Cloudflare Module Workers

Use Remix with Cloudflare module workers

Motivation

The official remix-cloudflare-workers adapter does not support Cloudflare Workers' new Module Worker format. Some of Workers' new features (like Durable Objects and D1) are not supported using the Service Worker syntax, making them inaccessible for use in your Remix app. This package adds compatibility with the new format.

Usage

Since the changes needed to use remix-cloudflare-module-workers are minimal, you can use the official create-remix command. When prompted where you want to deploy, choose "Cloudflare Workers"

``sh
npx create-remix@latest
`

cd into your project and install remix-cloudflare-module-workers

`sh
npm i remix-cloudflare-module-workers
`

Replace server.js with this snippet:

`typescript
import { createEventHandler } from "remix-cloudflare-module-workers";
import * as build from "@remix-run/dev/server-build";

export default {
fetch: createEventHandler({ build, mode: process.env.NODE_ENV }),
};
`

Change the serverDependenciesToBundle in remix.config.js:

`diff
- serverDependenciesToBundle: "all",
+ serverDependenciesToBundle: [/^(?!(__STATIC_CONTENT_MANIFEST)$).*$/u],
`

Run miniflare with the --modules flag in package.json:

`diff
"scripts": {
- "dev:miniflare": "cross-env NODE_ENV=development miniflare ./build/index.js --watch",
+ "dev:miniflare": "cross-env NODE_ENV=development miniflare ./build/index.js --watch --modules",
`

That's it! Run npm run dev to start the dev server.

Environment variables and bindings

Refer to the Workers docs on environment variables for more information.

With module Workers, environment variables and bindings are available on the env parameter passed to the Worker's fetch event handler. You can rewrite the fetch event handler to access them before passing the request to Remix's createEventHandler.

Rename server.js to server.ts:

`typescript
// server.ts

import { createEventHandler } from "remix-cloudflare-module-workers";
import * as build from "@remix-run/dev/server-build";

export type Environment = {
__STATIC_CONTENT: KVNamespace;
// add your env variable / bindings here
};

export default {
async fetch(request: Request, env: Environment, ctx: ExecutionContext) {
console.log(env);
return createEventHandler({
build,
mode: process.env.NODE_ENV,
})(request, env, ctx);
},
};
`

$3

To access the Worker's env throughout your Remix app, you can create a small helper service to easily set and retrieve the env.

`typescript
// services/environment.server.ts

export type Environment = {
__STATIC_CONTENT: KVNamespace; // this is required
YOUR_ENV_VARIABLE: string;
};

export function setEnvironment(e: Environment) {
env = e;
}

export let env: Environment;
`

And update server.ts as follows:

`diff
+ import { setEnvironment, type Environment } from "~/services/environment.server";

- export type Environment = {
- __STATIC_CONTENT: KVNamespace;
- };

export default {
async fetch(request: Request, env: Environment, ctx: ExecutionContext){
+ setEnvironment(env);
return createEventHandler({
build,
mode: process.env.NODE_ENV,
})(request, env, ctx);
},
};
`

Now, you can access the Worker's env anywhere (server-side) in your Remix app.

`typescript
import { env } from "~/services/environment.server";

console.log(env.YOUR_ENV_VARIABLE);
`

$3

Alternatively, you can also bind env to your loaders and actions context by using Remix's built-in getLoadContext. To get type suggestions, you'll need to override Remix's AppLoadContext type.

In server.ts

`diff
export type Environment = {
__STATIC_CONTENT: KVNamespace;
// add your env variable / bindings types here
};

+ declare module "@remix-run/server-runtime" {
+ interface AppLoadContext extends Environment {}
+ }

export default {
async fetch(request: Request, env: Environment, ctx: ExecutionContext){
+ function getLoadContext() {
+ return env;
+ }
return createEventHandler({
build,
+ getLoadContext,
mode: process.env.NODE_ENV,
})(request, env, ctx);
},
};
`

In your loaders and actions, you can use the context param now to access your environment variables and bindings.

`typescript
// app/routes/_index.tsx

export async function loader({ request, context }: LoaderArgs) {
console.log(context.YOUR_ENV_VARIABLE);

return json({
your_env: context.YOUR_ENV_VARIABLE,
});
}
`

$3

When developing your Remix app locally, create a .env file in the root of your project to define your environment variables. Remix uses Miniflare for development, read the Miniflare docs on environment variables for more information.

KV, D1 and other Workers APIs

With your Worker's env set up, you can access all bindings throughout your Remix app.

$3

Use Wrangler to create a KV namespace:

`sh
npx wrangler kv:namespace create
`

Add the generated kv_namespace to your wrangler.toml file:

`toml
kv_namespaces = [
{ binding = "", id = "" }
]
`

You can give binding any value you want. You'll be able to access this binding on the Worker's env parameter with the name you choose here.

To use this KV namespace in development mode, pass it to miniflare in your package.json:

`diff
"scripts": {
- "dev:miniflare": "cross-env NODE_ENV=development miniflare ./build/index.js --watch --modules",
+ "dev:miniflare": "cross-env NODE_ENV=development miniflare ./build/index.js --watch --kv YOUR_BINDING --kv YOUR_BINDING_2 --modules",
`

By default, KV data is stored in memory. To persist KV data between runs, add the --kv-persist flag to the miniflare command.

Add the KVNamespace to your Environment type.

`diff
export type Environment = {
__STATIC_CONTENT: KVNamespace;
+ YOUR_BINDING: KVNamespace;
};
`

Your KV database is now available on env if you are using the env helper service, or on context if you are loading env via getLoadContext.

References:

- Cloudflare Workers KV
- Miniflare KV
- Wrangler KV

$3

Workers uses better-sqlite3 to access D1:

`sh
npm i better-sqlite3
`

Use Wrangler to create a D1 database:

`sh
npx wrangler d1 create
`

Add the generated D1 namespace to your wrangler.toml file:

`toml
[[d1_databases]]
binding = ""
database_name = ""
database_id = ""
`

To develop locally, add your database to the miniflare command in your package.json:

`diff
"scripts": {
- "dev:miniflare": "cross-env NODE_ENV=development miniflare ./build/index.js --watch --modules",
+ "dev:miniflare": "cross-env NODE_ENV=development miniflare ./build/index.js --watch --d1 BINDING_NAME --modules",
`

Your D1 database is now available on the env object in your Remix app. For more info on how to bootstrap your D1 database and write queries for it, read the official Cloudflare D1 docs.

$3

With remix-cloudflare-module-workers`, all Workers features and APIs should be supported. Refer to the Cloudflare Workers docs and Miniflare docs (for local development) for the setup and usage of other Workers APIs.

Related Links

- Remix documentation on adapters
- Prior discussion on a ES modules Workers adapter