Feature: Adds Federation 2 Support

api/generate.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"fmt"
+	"regexp"
 	"syscall"
 
 	"github.com/99designs/gqlgen/codegen"
@@ -24,7 +25,20 @@ func Generate(cfg *config.Config, option ...Option) error {
 	}
 	plugins = append(plugins, resolvergen.New())
 	if cfg.Federation.IsDefined() {
-		plugins = append([]plugin.Plugin{federation.New()}, plugins...)
+		if cfg.Federation.Version == 0 { // default to using the user's choice of version, but if unset, try to sort out which federation version to use
+			urlRegex := regexp.MustCompile(`(?s)@link.*\(.*url:.*?"(.*?)"[^)]+\)`) // regex to grab the url of a link directive, should it exist
+
+			// check the sources, and if one is marked as federation v2, we mark the entirety to be generated using that format
+			for _, v := range cfg.Sources {
+				cfg.Federation.Version = 1
+				urlString := urlRegex.FindStringSubmatch(v.Input)
+				if urlString != nil && urlString[1] == "https://specs.apollo.dev/federation/v2.0" {
+					cfg.Federation.Version = 2
+					break
+				}
+			}
+		}
+		plugins = append([]plugin.Plugin{federation.New(cfg.Federation.Version)}, plugins...)
 	}
 
 	for _, o := range option {

api/generate_test.go

@@ -34,6 +34,13 @@ func TestGenerate(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "federation2",
+			args: args{
+				workDir: path.Join(wd, "testdata", "federation2"),
+			},
+			wantErr: false,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

api/option_test.go

@@ -26,29 +26,29 @@ func (t *testPlugin) MutateConfig(_ *config.Config) error {
 func TestReplacePlugin(t *testing.T) {
 	t.Run("replace plugin if exists", func(t *testing.T) {
 		pg := []plugin.Plugin{
-			federation.New(),
+			federation.New(1),
 			modelgen.New(),
 			resolvergen.New(),
 		}
 
 		expectedPlugin := &testPlugin{}
 		ReplacePlugin(expectedPlugin)(config.DefaultConfig(), &pg)
 
-		require.EqualValues(t, federation.New(), pg[0])
+		require.EqualValues(t, federation.New(1), pg[0])
 		require.EqualValues(t, expectedPlugin, pg[1])
 		require.EqualValues(t, resolvergen.New(), pg[2])
 	})
 
 	t.Run("add plugin if doesn't exist", func(t *testing.T) {
 		pg := []plugin.Plugin{
-			federation.New(),
+			federation.New(1),
 			resolvergen.New(),
 		}
 
 		expectedPlugin := &testPlugin{}
 		ReplacePlugin(expectedPlugin)(config.DefaultConfig(), &pg)
 
-		require.EqualValues(t, federation.New(), pg[0])
+		require.EqualValues(t, federation.New(1), pg[0])
 		require.EqualValues(t, resolvergen.New(), pg[1])
 		require.EqualValues(t, expectedPlugin, pg[2])
 	})

api/testdata/federation2/gqlgen.yml

@@ -0,0 +1,56 @@
+# Where are all the schema files located? globs are supported eg  src/**/*.graphqls
+schema:
+  - graph/*.graphqls
+
+# Where should the generated server code go?
+exec:
+  filename: graph/generated/generated.go
+  package: generated
+
+# Uncomment to enable federation
+federation:
+  filename: graph/generated/federation.go
+  package: generated
+
+# Where should any generated models go?
+model:
+  filename: graph/model/models_gen.go
+  package: model
+
+# Where should the resolver implementations go?
+resolver:
+  layout: follow-schema
+  dir: graph
+  package: graph
+
+# Optional: turn on use `gqlgen:"fieldName"` tags in your models
+# struct_tag: json
+
+# Optional: turn on to use []Thing instead of []*Thing
+# omit_slice_element_pointers: false
+
+# Optional: set to speed up generation time by not performing a final validation pass.
+# skip_validation: true
+
+# gqlgen will search for any type names in the schema in these go packages
+# if they match it will use them, otherwise it will generate them.
+autobind:
+  - "github.com/99designs/gqlgen/api/testdata/default/graph/model"
+
+# This section declares type mapping between the GraphQL and go type systems
+#
+# The first line in each type will be used as defaults for resolver arguments and
+# modelgen, the others will be allowed when binding to fields. Configure them to
+# your liking
+models:
+  ID:
+    model:
+      - github.com/99designs/gqlgen/graphql.ID
+      - github.com/99designs/gqlgen/graphql.Int
+      - github.com/99designs/gqlgen/graphql.Int64
+      - github.com/99designs/gqlgen/graphql.Int32
+  Int:
+    model:
+      - github.com/99designs/gqlgen/graphql.Int
+      - github.com/99designs/gqlgen/graphql.Int64
+      - github.com/99designs/gqlgen/graphql.Int32

api/testdata/federation2/graph/model/doc.go

@@ -0,0 +1 @@
+package model

api/testdata/federation2/graph/schema.graphqls

@@ -0,0 +1,31 @@
+# GraphQL schema example
+#
+# https://gqlgen.com/getting-started/
+extend schema
+  @link(url: "https://specs.apollo.dev/federation/v2.0",
+        import: ["@key", "@shareable", "@provides", "@external", "@tag", "@extends", "@override", "@inaccessible"])
+
+type Todo {
+  id: ID!
+  text: String!
+  done: Boolean!
+  user: User!
+}
+
+type User {
+  id: ID!
+  name: String!
+}
+
+type Query {
+  todos: [Todo!]!
+}
+
+input NewTodo {
+  text: String!
+  userId: String!
+}
+
+type Mutation {
+  createTodo(input: NewTodo!): Todo!
+}

codegen/config/package.go

@@ -12,6 +12,7 @@ import (
 type PackageConfig struct {
 	Filename string `yaml:"filename,omitempty"`
 	Package  string `yaml:"package,omitempty"`
+	Version  int    `yaml:"version,omitempty"`
 }
 
 func (c *PackageConfig) ImportPath() string {

docs/content/recipes/federation.md

@@ -19,6 +19,16 @@ federation:
   package: generated
 ```
 
+### Federation 2
+
+If you are using Apollo's Federation 2 standard, your schema should automatically be upgraded so long as you include the required `@link` directive within your schema. If you want to force Federation 2 composition, the `federation` configuration supports a `version` flag to override that. For example:
+
+```yml
+federation:
+  filename: graph/generated/federation.go
+  package: generated
+```
+
 ## Create the federated servers
 
 For each server to be federated we will create a new gqlgen project.

plugin/federation/federation.go

@@ -16,12 +16,17 @@ import (
 
 type federation struct {
 	Entities []*Entity
+	Version  int
 }
 
 // New returns a federation plugin that injects
 // federated directives and types into the schema
-func New() plugin.Plugin {
-	return &federation{}
+func New(version int) plugin.Plugin {
+	if version == 0 {
+		version = 1
+	}
+
+	return &federation{Version: version}
 }
 
 // Name returns the plugin name
@@ -51,6 +56,7 @@ func (f *federation) MutateConfig(cfg *config.Config) error {
 			Model: config.StringList{"github.com/99designs/gqlgen/graphql.Map"},
 		},
 	}
+
 	for typeName, entry := range builtins {
 		if cfg.Models.Exists(typeName) {
 			return fmt.Errorf("%v already exists which must be reserved when Federation is enabled", typeName)
@@ -63,22 +69,46 @@ func (f *federation) MutateConfig(cfg *config.Config) error {
 	cfg.Directives["key"] = config.DirectiveConfig{SkipRuntime: true}
 	cfg.Directives["extends"] = config.DirectiveConfig{SkipRuntime: true}
 
+	// Federation 2 specific directives
+	if f.Version == 2 {
+		cfg.Directives["shareable"] = config.DirectiveConfig{SkipRuntime: true}
+		cfg.Directives["link"] = config.DirectiveConfig{SkipRuntime: true}
+		cfg.Directives["tag"] = config.DirectiveConfig{SkipRuntime: true}
+		cfg.Directives["override"] = config.DirectiveConfig{SkipRuntime: true}
+		cfg.Directives["inaccessible"] = config.DirectiveConfig{SkipRuntime: true}
+	}
+
 	return nil
 }
 
 func (f *federation) InjectSourceEarly() *ast.Source {
+	input := `
+	scalar _Any
+	scalar _FieldSet
+
+	directive @external on FIELD_DEFINITION
+	directive @requires(fields: _FieldSet!) on FIELD_DEFINITION
+	directive @provides(fields: _FieldSet!) on FIELD_DEFINITION
+	directive @extends on OBJECT | INTERFACE
+`
+	// add version-specific changes on key directive, as well as adding the new directives for federation 2
+	if f.Version == 1 {
+		input += `
+	directive @key(fields: _FieldSet!) repeatable on OBJECT | INTERFACE
+`
+	} else if f.Version == 2 {
+		input += `
+	directive @key(fields: _FieldSet!, resolvable: Boolean) repeatable on OBJECT | INTERFACE
+	directive @link(import: [String!], url: String!) repeatable on SCHEMA
+	directive @shareable on OBJECT | FIELD_DEFINITION
+	directive @tag repeatable on OBJECT | FIELD_DEFINITION | INTERFACE | UNION
+	directive @override(from: String!) on FIELD_DEFINITION
+	directive @inaccessible on SCALAR | OBJECT | FIELD_DEFINITION | ARGUMENT_DEFINITION | INTERFACE | UNION | ENUM | ENUM_VALUE | INPUT_OBJECT | INPUT_FIELD_DEFINITION
+`
+	}
 	return &ast.Source{
-		Name: "federation/directives.graphql",
-		Input: `
-scalar _Any
-scalar _FieldSet
-
-directive @external on FIELD_DEFINITION
-directive @requires(fields: _FieldSet!) on FIELD_DEFINITION
-directive @provides(fields: _FieldSet!) on FIELD_DEFINITION
-directive @key(fields: _FieldSet!) repeatable on OBJECT | INTERFACE
-directive @extends on OBJECT | INTERFACE
-`,
+		Name:    "federation/directives.graphql",
+		Input:   input,
 		BuiltIn: true,
 	}
 }
@@ -290,10 +320,21 @@ func (f *federation) setEntities(schema *ast.Schema) {
 		//    }
 		if !e.allFieldsAreExternal() {
 			for _, dir := range keys {
-				if len(dir.Arguments) != 1 || dir.Arguments[0].Name != "fields" {
-					panic("Exactly one `fields` argument needed for @key declaration.")
+				if len(dir.Arguments) > 2 {
+					panic("More than two arguments provided for @key declaration.")
 				}
-				arg := dir.Arguments[0]
+				var arg *ast.Argument
+
+				// since keys are able to now have multiple arguments, we need to check both possible for a possible @key(fields="" fields="")
+				for _, a := range dir.Arguments {
+					if a.Name == "fields" {
+						if arg != nil {
+							panic("More than one `fields` provided for @key declaration.")
+						}
+						arg = a
+					}
+				}
+
 				keyFieldSet := fieldset.New(arg.Value.Raw, nil)
 
 				keyFields := make([]*KeyField, len(keyFieldSet))