Introduce connectors support to response caching

.gitleaks.toml

@@ -23,6 +23,8 @@
             "77700b93798ce98eaf75c3b02b70198e7b730ddb",
             # not a key: https://github.com/apollographql/router/pull/8326#issuecomment-3325655427
             "58bca0271d5a2046dfa7705a5418781bc456c787",
+            # Cache keys, not secret keys
+            "165156910be987f1d28b0c0013fe45ce2ccd23c6"
         ]
 
         paths = [
@@ -129,6 +131,7 @@
     [ rules.allowlist ]
         paths = [
             '''^docs/source/routing/performance/caching/response-caching/invalidation.mdx$''',
+            '''^docs/source/routing/performance/caching/response-caching/customization.mdx$''',
         ]
 
 [[ rules ]]

apollo-federation/src/connectors/expand/tests/mod.rs

@@ -7,6 +7,8 @@ use insta::glob;
 use crate::ApiSchemaOptions;
 use crate::connectors::expand::ExpansionResult;
 use crate::connectors::expand::expand_connectors;
+use crate::schema::FederationSchema;
+use crate::supergraph::extract_subgraphs_from_supergraph;
 
 #[test]
 fn it_expand_supergraph() {
@@ -29,6 +31,32 @@ fn it_expand_supergraph() {
     });
 }
 
+/// @cacheTag: The expanded supergraph's @join__directive `graphs`
+/// list includes all synthetic connector subgraphs, but only one owns the
+/// field — `extract_subgraphs_from_supergraph` must tolerate this.
+#[test]
+fn cache_tag_on_connector_field_does_not_crash_extraction() {
+    let to_expand = read_to_string(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/src/connectors/expand/tests/schemas/expand/cache_tag_on_connector.graphql"
+    ))
+    .unwrap();
+
+    let ExpansionResult::Expanded { raw_sdl, .. } =
+        expand_connectors(&to_expand, &ApiSchemaOptions::default()).unwrap()
+    else {
+        panic!("expected expansion");
+    };
+
+    let schema = apollo_compiler::Schema::parse_and_validate(&raw_sdl, "expanded.graphql")
+        .expect("expanded supergraph should be valid GraphQL");
+    let fed_schema =
+        FederationSchema::new(schema.into_inner()).expect("should create FederationSchema");
+
+    extract_subgraphs_from_supergraph(&fed_schema, Some(true))
+        .expect("extract_subgraphs_from_supergraph should succeed");
+}
+
 #[test]
 fn it_ignores_supergraph() {
     insta::with_settings!({prepend_module_to_snapshot => false}, {

apollo-federation/src/connectors/expand/tests/schemas/expand/cache_tag_on_connector.graphql

@@ -0,0 +1,78 @@
+schema
+  @link(url: "https://specs.apollo.dev/link/v1.0")
+  @link(url: "https://specs.apollo.dev/join/v0.5", for: EXECUTION)
+  @link(url: "https://specs.apollo.dev/connect/v0.1", for: EXECUTION)
+  @link(url: "https://specs.apollo.dev/cacheTag/v0.1", for: EXECUTION)
+  @join__directive(graphs: [CONNECTORS], name: "link", args: {url: "https://specs.apollo.dev/connect/v0.1", import: ["@connect", "@source"]})
+  @join__directive(graphs: [CONNECTORS], name: "source", args: {name: "example", http: {baseURL: "http://example"}})
+{
+  query: Query
+}
+
+directive @join__directive(graphs: [join__Graph!], name: String!, args: join__DirectiveArguments) repeatable on SCHEMA | OBJECT | INTERFACE | FIELD_DEFINITION
+
+directive @join__enumValue(graph: join__Graph!) repeatable on ENUM_VALUE
+
+directive @join__field(graph: join__Graph, requires: join__FieldSet, provides: join__FieldSet, type: String, external: Boolean, override: String, usedOverridden: Boolean, overrideLabel: String, contextArguments: [join__ContextArgument!]) 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, resolvable: Boolean! = true, isInterfaceObject: Boolean! = false) repeatable on OBJECT | INTERFACE | UNION | ENUM | INPUT_OBJECT | SCALAR
+
+directive @join__unionMember(graph: join__Graph!, member: String!) repeatable on UNION
+
+directive @link(url: String, as: String, for: link__Purpose, import: [link__Import]) repeatable on SCHEMA
+
+input join__ContextArgument {
+  name: String!
+  type: String!
+  context: String!
+  selection: join__FieldValue!
+}
+
+scalar join__DirectiveArguments
+
+scalar join__FieldSet
+
+scalar join__FieldValue
+
+enum join__Graph {
+  CONNECTORS @join__graph(name: "connectors", url: "none")
+}
+
+scalar link__Import
+
+enum link__Purpose {
+  """
+  `SECURITY` features provide metadata necessary to securely resolve fields.
+  """
+  SECURITY
+
+  """
+  `EXECUTION` features provide metadata necessary for operation execution.
+  """
+  EXECUTION
+}
+
+type Product
+  @join__type(graph: CONNECTORS, key: "id")
+{
+  id: ID!
+  title: String @join__field(graph: CONNECTORS)
+}
+
+type Query
+  @join__type(graph: CONNECTORS)
+{
+  users: [User] @join__field(graph: CONNECTORS) @join__directive(graphs: [CONNECTORS], name: "federation__cacheTag", args: {format: "users"}) @join__directive(graphs: [CONNECTORS], name: "connect", args: {source: "example", http: {GET: "/users"}, selection: "id name"})
+  products: [Product] @join__field(graph: CONNECTORS) @join__directive(graphs: [CONNECTORS], name: "connect", args: {source: "example", http: {GET: "/products"}, selection: "id title"})
+}
+
+type User
+  @join__type(graph: CONNECTORS, key: "id")
+{
+  id: ID!
+  name: String @join__field(graph: CONNECTORS)
+}

apollo-federation/src/connectors/expand/tests/schemas/expand/cache_tag_on_connector.yaml

@@ -0,0 +1,27 @@
+subgraphs:
+  connectors:
+    routing_url: none
+    schema:
+      sdl: |
+        extend schema
+          @link(
+            url: "https://specs.apollo.dev/federation/v2.12"
+            import: ["@key", "@cacheTag"]
+          )
+          @link(url: "https://specs.apollo.dev/connect/v0.1", import: ["@connect", "@source"])
+          @source(name: "example", http: { baseURL: "http://example" })
+
+        type Query {
+          users: [User] @cacheTag(format: "users") @connect(source: "example", http: { GET: "/users" }, selection: "id name")
+          products: [Product] @connect(source: "example", http: { GET: "/products" }, selection: "id title")
+        }
+
+        type User @key(fields: "id") {
+          id: ID!
+          name: String
+        }
+
+        type Product @key(fields: "id") {
+          id: ID!
+          title: String
+        }

apollo-federation/src/connectors/expand/tests/snapshots/api@cache_tag_on_connector.graphql.snap

@@ -0,0 +1,21 @@
+---
+source: apollo-federation/src/connectors/expand/tests/mod.rs
+expression: api_schema
+input_file: apollo-federation/src/connectors/expand/tests/schemas/expand/cache_tag_on_connector.graphql
+---
+directive @defer(label: String, if: Boolean! = true) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+
+type Product {
+  id: ID!
+  title: String
+}
+
+type Query {
+  users: [User]
+  products: [Product]
+}
+
+type User {
+  id: ID!
+  name: String
+}