Set CORS headers

[glasser]

Because the handler exposed by this package is not a modular piece of middleware, it probably makes sense for it to function like startStandaloneServer and have the default behavior of setting access-control-allow-origin: * and friends. (Then potentially layer some mechanism for CORS configuration on top of that, or just tell people who need more configuration to do something like #38.)

[glasser]

Or is the theory that if you're using API Gateway you would just enable CORS via API Gateway rather than in the function?

[poad]

We suspect that this issue is caused by the fact that Apollo Server v4 no longer has an interface to directly link express middleware.

Currently, the cheapest solution is to wrap startServerAndCreateLambdaHandler(server) with Access-Control-Allow-Origin header instead of directly with the Lambda Handler, as shown below. header?

async function handler(event: GatewayEvent, context: Context, callback: Callback<APIGatewayProxyStructuredResultV2 | APIGatewayProxyResult>) {
  const apolloHandler = startServerAndCreateLambdaHandler(server);
  const resp = await apolloHandler(event, context, callback);
  return {
    ...resp,
    headers: {
      ...resp?.headers,
      'Access-Control-Allow-Origin': '*',
    },
  };
}

export default handler;

If possible, it would be great if startServerAndCreateLambdaHandler() could specify a callback function to customize the response.

[glasser]

Yes, though if you enjoyed that interface, you can see #38 for an alternate approach that doesn't use this package (and which is powered by the same package that powered apollo-server-lambda in AS3).

[poad]

@glasser Thx!
I suggested a different approach from #38 because the response tends to be slower with #38's approach and I wanted to support CORS with the Lambda Handler using less description.

[BlenderDude]

You can now use middleware to mutate headers on the way out with v2.0.0! See README for more info!

[BlenderDude]

We suspect that this issue is caused by the fact that Apollo Server v4 no longer has an interface to directly link express middleware.

Currently, the cheapest solution is to wrap startServerAndCreateLambdaHandler(server) with Access-Control-Allow-Origin header instead of directly with the Lambda Handler, as shown below. header?

async function handler(event: GatewayEvent, context: Context, callback: Callback<APIGatewayProxyStructuredResultV2 | APIGatewayProxyResult>) {
  const apolloHandler = startServerAndCreateLambdaHandler(server);
  const resp = await apolloHandler(event, context, callback);
  return {
    ...resp,
    headers: {
      ...resp?.headers,
      'Access-Control-Allow-Origin': '*',
    },
  };
}

export default handler;

If possible, it would be great if startServerAndCreateLambdaHandler() could specify a callback function to customize the response.

@poad

This "callback function" is now implemented as middlware in the new version!