You can use an AWS AppSync API as a subgraph in a federated graph with the following steps:
For a complete tutorial on integrating AppSync as part of an Apollo Federation architecture, see this AWS blog post.
Expose your AppSync API's schema to the gateway
A GraphQL service is aggregated by an Apollo federation gateway by providing its subgraph schema definition, with third party servers, a query called
_service, returning an extended GraphQL Schema Definition Language (SDL) response is required.
Define and extend entities
If any of your AppSync schema's object types are entities, you need to apply the
@key directive to them (as with any other subgraph library). Learn More.
Publish the subgraph schema with the Rover CLI
After you modify and deploy your AppSync schema, you can publish that schema to Apollo Studio with the Rover CLI tool
Click for a complete list of subgraph compatible server libraries
For a complete list of subgraph-compatible server libraries, see this article.