How to pass custom header from router to subgraph

[Gladys-LM]

I am trying to do a POC using apollo router + API-One, both deployed to k8s. API-One is a monolith graph and is expecting a custom header. I tried to use Postman to set the header for the post request to router endpoint, the traffic went from router to API-One fine but got error response because the custom header wasn't passed from router to API-One. Tried to tweak router configuration but didn't work. Any tips on how I can pass the custom header from router to API-One? Thanks.

[o0Ignition0o]

Hi, thanks for opening this discussion!

We're about to land our plugins system, which will allow you to cover this usecase. I'll get back to you on that once we merge it on main

[dakshas]

Hi, is there any update on this ?

[o0Ignition0o]

Indeed!

we know have fully fledged header propagation rules which you can configure with yml

please let me know if it covers your use case!

[andrew-kolesnikov]

Those who want to generate a custom header for subgraph inside the router, instead of forwarding from router downstream into subgraph, will need a custom plugin:

fn subgraph_service( &mut self, _name: &str, service: BoxService<SubgraphRequest, SubgraphResponse, BoxError>, ) -> BoxService<SubgraphRequest, SubgraphResponse, BoxError> { ServiceBuilder::new() .map_request(|mut req: SubgraphRequest| { req.subgraph_request.headers_mut().insert("foo", HeaderValue::from_str("bar").unwrap()); req }) .service(service) .boxed() }

[bnjjj]

Maybe I don't understand your need but it's already covered by the configuration file by using insert https://www.apollographql.com/docs/router/configuration/header-propagation/#insert

[andrew-kolesnikov]

Maybe I don't understand your need but it's already covered by the configuration file by using insert https://www.apollographql.com/docs/router/configuration/header-propagation/#insert

There are many common scenarios for which insert is not suitable, e.g. pass a JWT with custom claims generated inside the router downstream into a subgraph. The custom plugin suggested above looks like the only available option.

[bnjjj]

OK my bad, regarding your example I thought it was a static content

[garypen]

If writing a rust plugin seems like a challenge, perhaps write a rhai script to create and propagate.