keep the error path when redacting subgraph errors (#2273)

Fix #1818 

the path is used to decide whether to assign the error on the primary or
deferred response

NEXT_CHANGELOG.md

@@ -41,6 +41,14 @@ It defaults to 30 seconds.
 
 By [@o0Ignition0o](https://github.com/o0Ignition0o) in https://github.com/apollographql/router/pull/2271
 
+## 🐛 Fixes
+
+### Keep the error path when redacting subgraph errors ([Issue #1818](https://github.com/apollographql/router/issues/1818))
+
+Error redaction was erasing the error's path, which made it impossible to affect the errors to deferred responses. Now the redacted errors keep the path. Since the response shape for the primary and deferred responses are defined from the API schema, there is no possibility of leaking internal schema information here.
+
+By [@Geal](https://github.com/geal) in https://github.com/apollographql/router/pull/2273
+
 ## 🛠 Maintenance
 
 ### Return more consistent errors ([Issue #2101](https://github.com/apollographql/router/issues/2101))

apollo-router/src/plugins/include_subgraph_errors.rs

@@ -1,26 +1,18 @@
 use std::collections::HashMap;
 
-use once_cell::sync::Lazy;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use tower::BoxError;
 use tower::ServiceExt;
 
-use crate::error::Error as SubgraphError;
+use crate::json_ext::Object;
 use crate::plugin::Plugin;
 use crate::plugin::PluginInit;
 use crate::register_plugin;
 use crate::services::subgraph;
 use crate::SubgraphResponse;
 
-#[allow(clippy::field_reassign_with_default)]
-static REDACTED_ERROR_MESSAGE: Lazy<Vec<SubgraphError>> = Lazy::new(|| {
-    let mut error: SubgraphError = Default::default();
-
-    error.message = "Subgraph errors redacted".to_string();
-
-    vec![error]
-});
+static REDACTED_ERROR_MESSAGE: &str = "Subgraph errors redacted";
 
 register_plugin!("apollo", "include_subgraph_errors", IncludeSubgraphErrors);
 
@@ -57,7 +49,10 @@ impl Plugin for IncludeSubgraphErrors {
                 .map_response(move |mut response: SubgraphResponse| {
                     if !response.response.body().errors.is_empty() {
                         tracing::info!("redacted subgraph({sub_name_response}) errors");
-                        response.response.body_mut().errors = REDACTED_ERROR_MESSAGE.clone();
+                        for error in response.response.body_mut().errors.iter_mut() {
+                            error.message = REDACTED_ERROR_MESSAGE.to_string();
+                            error.extensions = Object::default();
+                        }
                     }
                     response
                 })
@@ -82,6 +77,7 @@ mod test {
     use std::sync::Arc;
 
     use bytes::Bytes;
+    use once_cell::sync::Lazy;
     use serde_json::Value as jValue;
     use serde_json_bytes::ByteString;
     use serde_json_bytes::Value;

apollo-router/src/spec/query.rs

@@ -976,10 +976,6 @@ impl Query {
         response_path: Option<&Path>,
         path: &Path,
     ) -> bool {
-        println!(
-            "Query::contains_error_path: path = {path}, query: {}",
-            self.string,
-        );
         let operation = if let Some(subselection) = subselection {
             // Get subselection from hashmap
             match self.subselections.get(&SubSelection {