An attempt at setting up a federated GraphQL server, containing a local gateway router and two subgraphs

Directories are:

• router/: (NodeJS) Contains the router gateway and supergraph
• authors/: (NodeJS) Contains subgraph A (Authors, extension of Book)
• publishers/: (NodeJS) Contains subgraph B (Publisher, extension of Author)
• books/: (Elixir/Absinthe) Contains subgraph B (Book, extension of Author)

Installation:

• Bun
• Elixir
• Apollo Rover CLI tool https://www.apollographql.com/docs/rover
• bun install in each directory

The node APIs just have hardcoded GraphQL SDL since this is the easiest path with Apollo Server.

In the Elixir API (books), use the custom mix task mix sdl. This uses the Absinthe Federation wrapper to generate the federation version of the SDL.

Composing the supergraph:

From within the router/ directory, run bun run supergraph:compose. The supergraph will output to router/src/supergraph.graphql

Running (development)

• Gateway:
  • From within router/, run bun start
• Authors subgraph:
  • From within authors/, run bun start
• Publishers subgraph:
  • From within publishers/, run bun start
• Books subgraph:
  • From within books, run mix phx.server