Use apollo-federation to generate the API schema (#4059)

Experimental option to test API schema generation using the
apollo-federation crate

Co-authored-by: Iryna Shestak <[email protected]>

Cargo.lock

@@ -243,6 +243,22 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "apollo-federation"
+version = "0.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38d08d88375b1cb778d4b663877fa5d2ba482180283d2071f4de75e697627d60"
+dependencies = [
+ "apollo-compiler 1.0.0-beta.4",
+ "indexmap 2.0.2",
+ "lazy_static",
+ "salsa",
+ "strum",
+ "strum_macros",
+ "thiserror",
+ "url",
+]
+
 [[package]]
 name = "apollo-parser"
 version = "0.6.3"
@@ -272,6 +288,7 @@ dependencies = [
  "access-json",
  "anyhow",
  "apollo-compiler 1.0.0-beta.4",
+ "apollo-federation",
  "arc-swap",
  "askama",
  "async-compression",

apollo-router/Cargo.toml

@@ -58,6 +58,7 @@ askama = "0.12.1"
 access-json = "0.1.0"
 anyhow = "1.0.75"
 apollo-compiler = "=1.0.0-beta.4"
+apollo-federation = "0.0.1"
 arc-swap = "1.6.0"
 async-compression = { version = "0.4.4", features = [
     "tokio",

apollo-router/src/configuration/mod.rs

@@ -168,6 +168,10 @@ pub struct Configuration {
     #[serde(default)]
     pub(crate) experimental_graphql_validation_mode: GraphQLValidationMode,
 
+    /// Set the API schema generation implementation to use.
+    #[serde(default)]
+    pub(crate) experimental_api_schema_generation_mode: ApiSchemaMode,
+
     /// Plugin configuration
     #[serde(default)]
     pub(crate) plugins: UserPlugins,
@@ -210,6 +214,21 @@ pub(crate) enum GraphQLValidationMode {
     Both,
 }
 
+/// GraphQL validation modes.
+#[derive(Clone, PartialEq, Eq, Default, Derivative, Serialize, Deserialize, JsonSchema)]
+#[derivative(Debug)]
+#[serde(rename_all = "lowercase")]
+pub(crate) enum ApiSchemaMode {
+    /// Use the new Rust-based implementation.
+    New,
+    /// Use the old JavaScript-based implementation.
+    #[default]
+    Legacy,
+    /// Use Rust-based and Javascript-based implementations side by side, logging warnings if the
+    /// implementations disagree.
+    Both,
+}
+
 impl<'de> serde::Deserialize<'de> for Configuration {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -292,6 +311,7 @@ impl Configuration {
         chaos: Option<Chaos>,
         uplink: Option<UplinkConfig>,
         graphql_validation_mode: Option<GraphQLValidationMode>,
+        experimental_api_schema_generation_mode: Option<ApiSchemaMode>,
         experimental_batching: Option<Batching>,
     ) -> Result<Self, ConfigurationError> {
         #[cfg(not(test))]
@@ -319,6 +339,7 @@ impl Configuration {
             limits: operation_limits.unwrap_or_default(),
             experimental_chaos: chaos.unwrap_or_default(),
             experimental_graphql_validation_mode: graphql_validation_mode.unwrap_or_default(),
+            experimental_api_schema_generation_mode:  experimental_api_schema_generation_mode.unwrap_or_default(),
             plugins: UserPlugins {
                 plugins: Some(plugins),
             },
@@ -367,6 +388,7 @@ impl Configuration {
         uplink: Option<UplinkConfig>,
         graphql_validation_mode: Option<GraphQLValidationMode>,
         experimental_batching: Option<Batching>,
+        experimental_api_schema_generation_mode: Option<ApiSchemaMode>,
     ) -> Result<Self, ConfigurationError> {
         let configuration = Self {
             validated_yaml: Default::default(),
@@ -378,6 +400,8 @@ impl Configuration {
             limits: operation_limits.unwrap_or_default(),
             experimental_chaos: chaos.unwrap_or_default(),
             experimental_graphql_validation_mode: graphql_validation_mode.unwrap_or_default(),
+            experimental_api_schema_generation_mode: experimental_api_schema_generation_mode
+                .unwrap_or_default(),
             plugins: UserPlugins {
                 plugins: Some(plugins),
             },

apollo-router/src/configuration/snapshots/apollo_router__configuration__tests__schema_generation.snap

@@ -1061,6 +1061,33 @@ expression: "&schema"
       },
       "additionalProperties": false
     },
+    "experimental_api_schema_generation_mode": {
+      "description": "Set the API schema generation implementation to use.",
+      "default": "legacy",
+      "oneOf": [
+        {
+          "description": "Use the new Rust-based implementation.",
+          "type": "string",
+          "enum": [
+            "new"
+          ]
+        },
+        {
+          "description": "Use the old JavaScript-based implementation.",
+          "type": "string",
+          "enum": [
+            "legacy"
+          ]
+        },
+        {
+          "description": "Use Rust-based and Javascript-based implementations side by side, logging warnings if the implementations disagree.",
+          "type": "string",
+          "enum": [
+            "both"
+          ]
+        }
+      ]
+    },
     "experimental_batching": {
       "description": "Batching configuration.",
       "default": {

apollo-router/src/query_planner/bridge_query_planner.rs

@@ -2,6 +2,7 @@
 
 use std::collections::HashMap;
 use std::fmt::Debug;
+use std::fmt::Write;
 use std::sync::Arc;
 use std::time::Instant;
 
@@ -122,8 +123,62 @@ impl BridgeQueryPlanner {
 
         let planner = Arc::new(planner);
 
-        let api_schema = planner.api_schema().await?;
-        let api_schema = Schema::parse(&api_schema.schema, &configuration)?;
+        let api_schema_string = match configuration.experimental_api_schema_generation_mode {
+            crate::configuration::ApiSchemaMode::Legacy => {
+                let api_schema = planner.api_schema().await?;
+                api_schema.schema
+            }
+            crate::configuration::ApiSchemaMode::New => schema.create_api_schema(),
+
+            crate::configuration::ApiSchemaMode::Both => {
+                let api_schema = planner.api_schema().await?;
+                let new_api_schema = schema.create_api_schema();
+
+                if api_schema.schema != new_api_schema {
+                    tracing::warn!(
+                        monotonic_counter.apollo.router.api_schema = 1u64,
+                        generation.result = "failed",
+                        "API schema generation mismatch: apollo-federation and router-bridge write different schema"
+                    );
+
+                    let differences = diff::lines(&api_schema.schema, &new_api_schema);
+                    let mut output = String::new();
+                    for diff_line in differences {
+                        match diff_line {
+                            diff::Result::Left(l) => {
+                                let trimmed = l.trim();
+                                if !trimmed.starts_with('#') && !trimmed.is_empty() {
+                                    writeln!(&mut output, "-{l}").expect("write will never fail");
+                                } else {
+                                    writeln!(&mut output, " {l}").expect("write will never fail");
+                                }
+                            }
+                            diff::Result::Both(l, _) => {
+                                writeln!(&mut output, " {l}").expect("write will never fail");
+                            }
+                            diff::Result::Right(r) => {
+                                let trimmed = r.trim();
+                                if trimmed != "---" && !trimmed.is_empty() {
+                                    writeln!(&mut output, "+{r}").expect("write will never fail");
+                                }
+                            }
+                        }
+                    }
+                    tracing::debug!(
+                        "different API schema between apollo-federation and router-bridge:\n{}",
+                        output
+                    );
+                } else {
+                    tracing::warn!(
+                        monotonic_counter.apollo.router.api_schema = 1u64,
+                        generation.result = VALIDATION_MATCH,
+                    );
+                }
+                api_schema.schema
+            }
+        };
+        let api_schema = Schema::parse(&api_schema_string, &configuration)?;
+
         let schema = Arc::new(schema.with_api_schema(api_schema));
         let introspection = if configuration.supergraph.introspection {
             Some(Arc::new(Introspection::new(planner.clone()).await))

apollo-router/src/spec/schema.rs

@@ -146,6 +146,12 @@ impl Schema {
         })
     }
 
+    pub(crate) fn create_api_schema(&self) -> String {
+        apollo_federation::Supergraph::from(self.definitions.clone())
+            .to_api_schema()
+            .to_string()
+    }
+
     pub(crate) fn with_api_schema(mut self, api_schema: Schema) -> Self {
         self.api_schema = Some(Box::new(api_schema));
         self