Cloudflare Workers environment variables and context

Cloudflare Workers does not set environment variables a global object like Node.js does with process.env. Workers binds environment variables to the worker's special fetch event handler thought a specific env argument.

This means accessing environment variables within Inngest function handlers isn't possible without explicitly passing them through from the worker event handler to the Inngest function handler.

We can accomplish this by use the middleware feature for Workers or when using Hono.

Creating middleware

You can create middleware which extracts the env argument from the Workers fetch event handler arguments for either Workers or Hono:

1. Use wrapRequest to capture the raw request arguments via requestArgs and store them as instance state.
2. Return the env object via transformFunctionInput to inject it into the function handler's context.

The requestArgs property in wrapRequest provides the raw arguments passed to the serve handler. For Workers, these are [request, env, ctx]. For Hono, this is [honoContext].

import { Inngest, Middleware } from 'inngest';

class WorkersBindingsMiddleware extends Middleware.BaseMiddleware {
  private env!: Env;

  async wrapRequest({ next, requestArgs }: Middleware.WrapRequestArgs) {
    // requestArgs contains the raw arguments passed to the Workers fetch handler
    // For Workers, these are [request, env, ctx]
    this.env = requestArgs[1] as Env;
    return await next();
  }

  transformFunctionInput(args: Middleware.TransformFunctionInputArgs) {
    return {
      ...args,
      ctx: {
        ...args.ctx,
        // Return the env object to the function handler's input args
        env: this.env,
      },
    };
  }
}

// Include the middleware when creating the Inngest client
export const inngest = new Inngest({
  id: 'my-workers-app',
  middleware: [WorkersBindingsMiddleware],
});

Within your functions, you can now access the environment variables via the env object argument that you returned in transformFunctionInput above. Here's an example function:

const myFn = inngest.createFunction(
  { id: 'my-fn', triggers: { event: 'demo/event.sent' } },
  // The "env" argument returned in transformFunctionInput is passed through:
  async ({ event, step, env }) => {

    // The env object will be typed as well:
    console.log(env.MY_VAR);
  }
);