local composition with CLI

[n1ru4l]

Sometimes when you want to develop locally it makes sense that you want to use the latest valid schema version on CDN, but replace some of the services locally because you develop locally.

The command should allow you to generate the supergraph and/or SDL locally (aka artifacts you would pass to a graphql gateway you run locally).

E.g. the following example would watch/poll htttp://localhost:3000/graphql, use the Hive GraphQL API for doing composition then write it to the supergraph.sdl file. If there was already a users service within the registry on GraphQL Hive it would be completely replaced by the local service.

hive dev --watch --service users --url http://localhost:3000/graphql  --out supergraph.sdl

If you want to replace multiple services locally you could just pass more parameters:

hive dev --watch \
  --service users --url http://localhost:3000/graphql \
  --service posts --url http://localhost:3001/graphql \
  --out supergraph.sdl

After each successful composition we could send a system push notification and/or display the changes on the CLI. 🤔

Note: We cannot do the composition locally as users could configure a wide range of custom external composition services. because of that we always need to do the composition through the API. In order to reduce the amount of network calls we can always check whether our local schemas have changed before doing the call.

Note: We cannot serve a gateway ourselves, as we don't know what composition type is used. We can only generate the artifact and write it to a file. Users are then advised to use their gateway of choice for consuming/watching that file.

[kamilkisiela]

https://the-guild.dev/graphql/hive/product-updates/2024-04-04-hive-dev-command