Environment Variable interpolation in mesh compose

[sarathkcm]

Hello,

I wanted to know if it's possible to use environment variables in the mesh config (v1) for endpoints, so that the schema gets generated for one URL (local or a dev url) but the queries get executed for another URL provided when running the application in production.

I tried configuring endpoint and source both as per the docs, but it seems like source URL should point to a schema file itself and not introspection URL.

Is this possible?

[ardatan]

Mesh Compose fetches source once on the composition then you don't have anything to do with that while running in the production because all the data needed is available inside the supergraph.
So you can basically use process.env as any other Nodejs application; source: process.env['MY_SOURCE_URL']
endpoint can be dynamic, so you can use endpoint: "{env.MY_SOURCE_URL}"
https://the-guild.dev/graphql/mesh/v1/source-handlers#from-environment-variables

[sarathkcm]

Thank you for your reply.

This is actually what I have been trying to make work.

export const composeConfig = defineConfig({
  subgraphs: [
    {
         sourceHandler: loadGraphQLHTTPSubgraph('Users', {
            endpoint: '{env.MY_SOURCE_URL}',
            source: process.env.MY_SOURCE_URL
      })
    }
  ]

However, this doesn't work and gives error when fetching the schema.
(The source URL is same as the endpoint URL which is a graphql endpoint. I don't have a URL to the schema file and was hoping it would work similar to the endpoint field and fetch schema through introspection)

If I provide only endpoint: '{env.MY_SOURCE_URL}' - then it shows error " cannot fetch {env.MY_SOURCE_URL}, invalid protocol". Is this the expectation or is it a bug? I checked the source code and I don't see usage of string interpolation anywhere in the compose-cli code.

If I replace the endpoint directly in the generated supergraph.graphl with "{env.MY_SOURCE_URL}", the hive gateway is able to interpolate it and able to federate the queries correctly. It's only the mesh generation part I am facing problems with.

[ardatan]

It should be fixed in;
@graphql-mesh/[email protected]

[sarathkcm]

I will give it a try and report back.

Thanks a lot. I just saw that you published this version a minute ago and I am in awe. Thanks a lot for your contributions to the community.

[sarathkcm]

It worked for mesh-compose. Thank you again.

Somehow running the hive gateway now doesn't interpolate the endpoints (took the latest of all packages). I'm wondering if I made the wrong assumption that it was working earlier (probably overwrote the changes in supergraph.graphql by running compose again)

[sarathkcm]

Had to solve it by using the following code in Hive gateway config, leaving it here for anyone else facing the same issue.

Not sure if it's a bug in hive gateway or I'm doing somehting wrong.

import * as FetchAPI from '@whatwg-node/fetch'
import { stringInterpolation } from '@graphql-mesh/string-interpolation;

import fetch from 'node-fetch'
import { defineConfig } from '@graphql-hive/gateway'
 
export const gatewayConfig = createGatewayRuntime({
  fetchAPI: {
    ...FetchAPI,
    fetch: (url, options) => FetchAPI.fetch(stringInterpolation.parse(url, { env: process.env }), options)
  }
})