Supports all Federation versions prior to v2.4.0. Drop-in replacement for @apollo/composition.

🚧 Work in progress, so please check TODOs.

• Open Source (MIT License)
• identical API
• same set of validation rules and exact same error messages
• produces Supergraph SDL (can be used with Apollo Router and every tool that supports Supergraph SDL)
• does not support Hints
• a lot faster! 5x faster when composing and validating simple schemas, but 28x faster at big scale.

# NPM
npm install @theguild/federation-composition
# PNPM
pnpm add @theguild/federation-composition
# Yarn
yarn add @theguild/federation-composition

import { parse } from 'graphql'
import { composeServices, compositionHasErrors } from '@theguild/federation-composition'

const result = composeServices([
  {
    name: 'users',
    typeDefs: parse(/* GraphQL */ `
      extend schema @link(url: "https://specs.apollo.dev/federation/v2.3", import: ["@key"])

      type User @key(fields: "id") {
        id: ID!
        name: String!
      }

      type Query {
        users: [User]
      }
    `)
  },
  {
    name: 'comments',
    typeDefs: parse(/* GraphQL */ `
      extend schema
        @link(url: "https://specs.apollo.dev/federation/v2.3", import: ["@key", "@external"])

      extend type User @key(fields: "id") {
        id: ID! @external
        comments: [Comment]
      }

      type Comment {
        id: ID!
        text: String!
        author: User!
      }
    `)
  }
])

if (compositionHasErrors(result)) {
  console.error(result.errors)
} else {
  console.log(result.supergraphSdl)
}

Install the dependencies:

pnpm install

Run the tests:

pnpm test

• Grab one of the failing tests and fix it.
• Add new tests to cover more cases.
• Add missing rules.
• Look for // TODO: comments in the code and fix/implement them.
• Todos with // TODO: T[NUMBER] are on Notion.
• Look for skipIf or skip in the tests.
• Refactor code (piece by piece) if you feel like it.

✅ Done

🚧 Work in progress

• ✅ NO_QUERIES
• ✅ TYPE_KIND_MISMATCH
• ✅ EXTENSION_WITH_NO_BASE
• ✅ FIELD_TYPE_MISMATCH
• ✅ FIELD_ARGUMENT_TYPE_MISMATCH
• ✅ EXTERNAL_TYPE_MISMATCH
• ✅ ENUM_VALUE_MISMATCH
• ✅ EMPTY_MERGED_ENUM_TYPE
• ✅ EMPTY_MERGED_INPUT_TYPE
• ✅ OVERRIDE_SOURCE_HAS_OVERRIDE
• ✅ EXTERNAL_MISSING_ON_BASE
• ✅ REQUIRED_ARGUMENT_MISSING_IN_SOME_SUBGRAPH
• ✅ REQUIRED_INPUT_FIELD_MISSING_IN_SOME_SUBGRAPH
• ✅ EXTERNAL_ARGUMENT_MISSING
• ✅ INPUT_FIELD_DEFAULT_MISMATCH
• ✅ FIELD_ARGUMENT_DEFAULT_MISMATCH
• ✅ DEFAULT_VALUE_USES_INACCESSIBLE
• ✅ ONLY_INACCESSIBLE_CHILDREN
• ✅ REFERENCED_INACCESSIBLE
• ✅ INTERFACE_KEY_MISSING_IMPLEMENTATION_TYPE
• ✅ INVALID_FIELD_SHARING
• ✅ PROVIDES_INVALID_FIELDS_TYPE
• ✅ INVALID_GRAPHQL
• ✅ OVERRIDE_ON_INTERFACE
• ✅ OVERRIDE_FROM_SELF_ERROR
• ✅ QUERY_ROOT_TYPE_INACCESSIBLE
• ✅ PROVIDES_UNSUPPORTED_ON_INTERFACE
• ✅ REQUIRES_UNSUPPORTED_ON_INTERFACE
• ✅ KEY_UNSUPPORTED_ON_INTERFACE
• ✅ KEY_INVALID_FIELDS_TYPE
• ✅ KEY_FIELDS_HAS_ARGS
• ✅ KEY_FIELDS_SELECT_INVALID_TYPE
• ✅ KEY_INVALID_FIELDS
• ✅ REQUIRES_INVALID_FIELDS
• ✅ REQUIRES_INVALID_FIELDS_TYPE
• ✅ MERGED_DIRECTIVE_APPLICATION_ON_EXTERNAL
• ✅ INTERFACE_KEY_NOT_ON_IMPLEMENTATION
• ✅ PROVIDES_FIELDS_MISSING_EXTERNAL
• ✅ REQUIRES_FIELDS_MISSING_EXTERNAL
• ✅ PROVIDES_ON_NON_OBJECT_FIELD
• ✅ INVALID_SUBGRAPH_NAME
• ✅ PROVIDES_FIELDS_HAS_ARGS
• ✅ PROVIDES_INVALID_FIELDS
• ✅ EXTERNAL_UNUSED
• ✅ DIRECTIVE_COMPOSITION_ERROR
• ✅ ROOT_QUERY_USED
• ✅ ROOT_MUTATION_USED
• ✅ ROOT_SUBSCRIPTION_USED
• ✅ INVALID_SHAREABLE_USAGE
• ✅ DIRECTIVE_DEFINITION_INVALID
• ✅ KEY_DIRECTIVE_IN_FIELDS_ARG
• ✅ PROVIDES_DIRECTIVE_IN_FIELDS_ARG
• ✅ REQUIRES_DIRECTIVE_IN_FIELDS_ARG
• ✅ TYPE_DEFINITION_INVALID
• ✅ OVERRIDE_COLLISION_WITH_ANOTHER_DIRECTIVE

• INTERFACE_OBJECT_USAGE_ERROR
• INTERFACE_FIELD_NO_IMPLEM
• SATISFIABILITY_ERROR
• DISALLOWED_INACCESSIBLE
• DOWNSTREAM_SERVICE_ERROR
• EXTERNAL_ARGUMENT_DEFAULT_MISMATCH
• EXTERNAL_ARGUMENT_TYPE_MISMATCH
• EXTERNAL_COLLISION_WITH_ANOTHER_DIRECTIVE
• IMPLEMENTED_BY_INACCESSIBLE
• INVALID_FEDERATION_SUPERGRAPH
• LINK_IMPORT_NAME_MISMATCH
• REQUIRED_INACCESSIBLE
• SHAREABLE_HAS_MISMATCHED_RUNTIME_TYPES
• UNSUPPORTED_FEATURE
• UNSUPPORTED_LINKED_FEATURE
• SATISFIABILITY_ERROR - deeply nested key fields
• SATISFIABILITY_ERROR - fragments in keys
• SATISFIABILITY_ERROR - support interfaces... (kill me)
• SATISFIABILITY_ERROR - @require - check if fields defined by @require can be resolved by current subgraph or by moving to other subgraphs.
• SATISFIABILITY_ERROR - @provides?
• more accurate key fields comparison (I did string ≠ string but we need to make it better)
• support @interfaceObject
• support [String!]! and [String!] comparison, not only String! vs String