How to forward headers & request to subgraph and to another subgraph

[iSreekanth]

Hello Everyone,

We are new to GraphQL language and currently implementing a middleware layer with apollo studio.

Currently, we have two subgraphs (Cart & Product) and one supergraph (router gateway).

And the use case is,

To get the user cart, the front-end team must pass the token in the authorization header along with some request parameters (ex: locale, Currency code). So that the cart subgraph can use them to get his/her basket and then get the product entity from Product Subgraph.

in cart.graphql, we have added Product Entity

extend type Product @key(fields: "id") { id: ID! @external }

And our config.yaml file is

cors:
  origins:
    - http://localhost:3000 # Allows any locally-running client to run against your Router
    - https://studio.apollographql.com # Allows Apollo Studio to still run queries against your Router
federation_version: =2.3.2
subgraphs:
  cart:
    routing_url: http://localhost:4002
    schema:
      file: ../subgraph-cart/cart.graphql
  products:
    routing_url: http://localhost:4001
    schema:
      file: ../subgraph-products/products.graphql
headers:
  subgraphs:
    cart:
      request:
        - propagate:
            matching: ".*"

But we are facing two issues here,

• Not getting the authorization header value to the cart subgraph. We are calling cart query from the Router server (http://127.0.0.1:4000/)
• Request is not getting forwarded to Product Subgraph. This means we are not getting either the authorization header or request parameters.

Could you please suggest to us?

Thanks,
Sreekanth

[garypen]

I'm not sure why your headers aren't being propagated to the cart subgraph. It may be because you have quoted your matching pattern. I don't think that is valid syntax.

Your request may not result in a fetch from products, but if it does, then it won't receive any forwarded headers, because you have only configured forwarding to your cart subgraph. If you want all headers to be forwarded to all subgraphs, use the all syntax in your configuration.

We have a number of examples of how to configure this.

Here's how to propagate all headers to all subgraphs:

headers:
  all: # Header rules for all subgraphs
    request:
      - propagate:
          matching: .*

[iSreekanth]

Thanks for your reply.

We have even tried with all and removing the quotes from the matching pattern too. But still, the headers are not getting forwarded.

headers:
  all: # Header rules for all subgraphs
    request:
      - propagate:
          matching: .*

I mean, from router, the request is only coming to the cart subgraph but not getting forwarded to the product subgraph.

Here is our folder structure,

And we are using the below commands to start the router server

rover supergraph compose --config ./config.yaml --output supergraph.graphql
./router --dev --supergraph supergraph.graphql

And, another query, do we need to execute these two commands every time we change config.yaml file?

Thanks,
Sreekanth

[garypen]

I think you are confused about how to use rover and the router. In your first line, you appear to be passing a router configuration config.yaml to rover. I'm not sure what effect that will have, but I imagine it isn't the effect you are looking for. You can find out more information about about how to configure rover.

The second line starts your router with no configuration at all, which is a valid use case, but not the use case you are looking for.

I recommend that you read all of our documentation about using rover and the router thoroughly before proceeding. Once you've read the documentation, you'll understand that the commands you are probably looking for are something like:

rover supergraph compose --output supergraph.graphql
./router --dev --supergraph supergraph.graphql --config ./config.yaml

[iSreekanth]

Thanks for your reply.

We have followed this article to create supergraph file.
https://www.apollographql.com/docs/rover/configuring/#writing-to-a-file

Then we tried to use the supergraph.graphql to start the router server.

If we try with ./router --dev --supergraph supergraph.graphql --config ./config.yaml, getting the below exception

2023-05-31T08:08:54.659658Z  INFO Apollo Router v1.12.1 // (c) Apollo Graph, Inc. // Licensed as ELv2 (https://go.apollo.dev/elv2)
2023-05-31T08:08:54.660722Z  INFO Anonymous usage data is gathered to inform Apollo product development.  See https://go.apollo.dev/o/privacy for details.
2023-05-31T08:08:54.681332Z  INFO Running with *development* mode settings which facilitate development experience (e.g., introspection enabled)
2023-05-31T08:08:54.739401Z  WARN configuration could not be upgraded automatically as it had errors
2023-05-31T08:08:54.745127Z ERROR configuration had errors: 
1. at line 5

  cors:
    origins:
      - http://localhost:3000 # Allows any locally-running client to run against your Router
      - https://studio.apollographql.com # Allows Apollo Studio to still run queries against your Router
┌ federation_version: =2.3.2
└-----> Additional properties are not allowed ('federation_version' was unexpected)

1. at line 6

    origins:
      - http://localhost:3000 # Allows any locally-running client to run against your Router
      - https://studio.apollographql.com # Allows Apollo Studio to still run queries against your Router
  federation_version: =2.3.2
┌ subgraphs:
|   cart:
|     routing_url: http://localhost:4002
|     schema:
|       file: ../subgraph-cart/cart.graphql
|   products:
|     routing_url: http://localhost:4001
|     schema:
|       file: ../subgraph-products/products.graphql
└-----> Additional properties are not allowed ('subgraphs' was unexpected)


2023-05-31T08:08:54.745846Z  INFO stopped
2023-05-31T08:08:54.747161Z ERROR no valid configuration was supplied

Could you please assist us with what is missing in the YAML file?

[iSreekanth]

We just realized that these two yamls should be different.
After making the necessary changes, the headers are getting forwarded.

But the request values are not getting forwarded from one Subgraph to another Subgraph.

We have given the product model as an entity in the cart subgraph below

extend type Product @key(fields: "id") {
  id: ID! @external
}

And then from the cart resolver.js, we are trying to send the Product ID & extra info

ProductLineItem: {
    product(productLineItem) {
      return {
        __typename: "Product",
         id: productLineItem.productId,
         siteInfo: { siteId: "INT", locale: "en-NL", currency: "EUR" }
      };
    }
  },

But we are only getting __typename and id.

We even tried adding siteInfo property to the product entity in cart graphql like below

extend type Product @key(fields: "id") {
  id: ID! @external
  siteInfo: SiteInfo!
}

but getting the GraphQL validation error,

AggregateGraphQLError [GraphQLError]: The schema is not a valid GraphQL schema.. Caused by:
The type of "Product.siteInfo" must be Output Type but got "SiteInfo!", a NonNullType.

Here is our request body which is been triggered from supergraph - http://127.0.0.1:4000/.

query ExampleQuery($id: String!, $siteInfo: SiteInfo!) {
  getCart(id: $id, siteInfo: $siteInfo) {
    productLineItems {
      itemId
      product {
        id
        name
        categoryId
      }
    }
  }
}

{
  "id": "619d86f8acfdb406bba53e3718",
  "siteInfo": {
    "siteId": "INT",
    "locale": "en-NL",
    "currency": "EUR"
  }
}

Could you please assist in getting the SiteInfo values into the Product subgraph?

[garypen]

These are good questions, but I think that you've reached the point where there are better ways to get answers. This blog post provides more details about the Apollo GraphOS Community Discord Server and I'm sure that the people there will be able to provide good answers to this kind of question.

[iSreekanth]

I have also posted the same question there too.

Thanks for your reply.

Closing the question here.