Federation 2 Composition Examples

Contents

• ./examples - various examples of subgraphs with supergraph.yaml config that can be used with the rover fed2 subcommand installed. See the main README.md for rover install instructions.

Using the rover CLI with the examples

Run an example:

cd ./basic

rover fed2 supergraph compose --config ./supergraph.yaml

Verify it composes successfully:

rover fed2 supergraph compose --config ./supergraph.yaml
WARN: [InconsistentFieldType]: Field "A.v1" has mismatched, but compatible, types across subgraphs: will use type "Int" (from subgraph "a") in supergraph but "A.v1" has subtype "Int!" in subgraph "b"

CoreSchema:

schema
  @core(feature: "https://specs.apollo.dev/core/v0.2")
  @core(feature: "https://specs.apollo.dev/join/v0.2", for: EXECUTION)
{
  query: Query
}

directive @core(feature: String!, as: String, for: core__Purpose) repeatable on SCHEMA

directive @join__field(graph: join__Graph!, requires: join__FieldSet, provides: join__FieldSet) repeatable on FIELD_DEFINITION | INPUT_FIELD_DEFINITION

directive @join__graph(name: String!, url: String!) on ENUM_VALUE

directive @join__implements(graph: join__Graph!, interface: String!) repeatable on OBJECT | INTERFACE

directive @join__type(graph: join__Graph!, key: join__FieldSet, extension: Boolean! = false) repeatable on OBJECT | INTERFACE | UNION | ENUM | INPUT_OBJECT | SCALAR

type A
  @join__type(graph: A, key: "k")
  @join__type(graph: B, key: "k")
{
  k: Int
  v1: Int
  v2: String @join__field(graph: A)
  v3: Int @join__field(graph: B)
}

enum core__Purpose {
  """
  `SECURITY` features provide metadata necessary to securely resolve fields.
  """
  SECURITY

  """
  `EXECUTION` features provide metadata necessary for operation execution.
  """
  EXECUTION
}

scalar join__FieldSet

enum join__Graph {
  A @join__graph(name: "a", url: "http://a:4000/graphql")
  B @join__graph(name: "b", url: "http://b:4000/graphql")
}

type Query
  @join__type(graph: A)
  @join__type(graph: B)
{
  a: A! @join__field(graph: A)
}

Done!

Additional rover info

https://www.apollographql.com/docs/rover/