Disable _service field in Apollo Server for @apollo/subgraph

[smyrick]

The _service field allows for runtime introspection of the full schema with Federated directives. It is helpful for Rover to fetch the schema if needed. However, if I have a schema file I can use to publish and share the schema the _service field is a security risk to potentially over expose the schema information. Just like how we recommend turning off introspection in production we should also have the option to turn off _service in production.

This is part an Apollo Server issue as well, but the library that adds the field is here. I will leave it up to the team to decide the best place to accept configuration options

Option 1

Disable adding the field in the first place

const options = {
  disableFederationServiceField: true
};

// New options param
const schema = buildSubgraphSchema({ typeDefs, resolvers, options });

Option 2

Infer from introspection config

const server = new ApolloServer({
  typeDefs,
  resolvers,
  introspection: false // Infer from here to hide the `_service` field ??
});