Global context (Async Local Storage)

[A-Shleifman]

The context Apollo Server exposes through resolvers is very convenient when using it within the same function, however, when more layers are added, passing ctx all around becomes messy.

Let's say we have a tenantId and tenantName that we extract from headers on every request. We need to pass them on to internal APIs down the line, but we have the following structure:

resolver.ts => service.ts => internalApiRequests.ts

Can we pass ctx down to the function that consumes it? - absolutely, is it clean? - no.

I tried writing an express middleware that would wrap next() in Node's AsyncLocalStorage, but it doesn't work. This was brought up previously regarding a library that was trying to achieve the same goal.

Then I wrote a wrapper withCtx that wraps around resolvers and the context becomes available in all downstream functions, but I have to wrap every resolver manually.

Is there a way to make express middleware work? Alternatively, is there some kind of apollo middleware that would allow wrapping the rest of the request in an ALS?

[A-Shleifman]

Using localStorage.enterWith instead of localStorage.run does the trick:

app.use((req, res, next) => {
  // localStorage.run(context, next)) <-- this doesn't work
  localStorage.enterWith(context);

  next();
});

Full solution: https://codesandbox.io/s/pensive-beaver-7w88e

[ghost]

Both localStorage.enterWith and localStorage.run work for me in apollo-server-express@2.26.0.

Same code from https://codesandbox.io/s/pensive-beaver-7w88e doesnt work in 3.0.0

Edit:
Doesn't work in Node 18

[A-Shleifman]

Updated and slightly simplified example with Apollo 3 and Node 16

Open a new terminal in codesandbox and run yarn start