Improve Prebid auction diagnostics (#671)

Author: ChristianPavilonis

crates/js/lib/build-all.mjs

@@ -12,7 +12,7 @@
  *   TSJS_PREBID_ADAPTERS — Comma-separated list of Prebid.js bid adapter
  *     names to include in the bundle (e.g. "rubicon,appnexus,openx").
  *     Each name must have a corresponding {name}BidAdapter.js module in
- *     the prebid.js package. Default: "rubicon".
+ *     the prebid.js package. Default: no adapters.
  *
  *   TSJS_PREBID_USER_ID_MODULES — Ignored for production builds. User ID
  *     modules are selected from src/integrations/prebid/user_id_modules.json
@@ -37,7 +37,8 @@ const integrationsDir = path.join(srcDir, 'integrations');
 // Prebid adapter generation
 // ---------------------------------------------------------------------------
 
-const DEFAULT_PREBID_ADAPTERS = 'rubicon';
+const DEFAULT_PREBID_ADAPTERS = '';
+const DEFAULT_PREBID_ADAPTERS_DESCRIPTION = DEFAULT_PREBID_ADAPTERS || 'no adapters';
 const ADAPTERS_FILE = path.join(integrationsDir, 'prebid', '_adapters.generated.ts');
 const USER_IDS_FILE = path.join(integrationsDir, 'prebid', '_user_ids.generated.ts');
 
@@ -69,20 +70,12 @@ const LIVE_INTENT_SHIM = path.join(
  * logged and skipped.
  */
 function generatePrebidAdapters() {
-  const raw = process.env.TSJS_PREBID_ADAPTERS || DEFAULT_PREBID_ADAPTERS;
+  const raw = process.env.TSJS_PREBID_ADAPTERS ?? DEFAULT_PREBID_ADAPTERS;
   const names = raw
     .split(',')
     .map((s) => s.trim())
     .filter(Boolean);
 
-  if (names.length === 0) {
-    console.warn(
-      '[build-all] TSJS_PREBID_ADAPTERS is empty, falling back to default:',
-      DEFAULT_PREBID_ADAPTERS
-    );
-    names.push(DEFAULT_PREBID_ADAPTERS);
-  }
-
   const modulesDir = path.join(__dirname, 'node_modules', 'prebid.js', 'modules');
 
   // Validate each adapter and build import lines
@@ -100,22 +93,26 @@ function generatePrebidAdapters() {
   }
 
   if (imports.length === 0) {
-    console.error(
-      '[build-all] WARNING: No valid Prebid adapters found, bundle will have no client-side adapters'
-    );
+    if (names.length === 0) {
+      console.log(
+        '[build-all] No Prebid adapters configured; bundle will have no client-side adapters'
+      );
+    } else {
+      console.error(
+        '[build-all] WARNING: No valid Prebid adapters found, bundle will have no client-side adapters'
+      );
+    }
   }
 
-  const content = [
+  const header = [
     '// Auto-generated by build-all.mjs — manual edits will be overwritten at build time.',
     '//',
     '// Controls which Prebid.js bid adapters are included in the bundle.',
     '// Set the TSJS_PREBID_ADAPTERS environment variable to a comma-separated list',
     '// of adapter names (e.g. "rubicon,appnexus,openx") before building.',
-    `// Default: "${DEFAULT_PREBID_ADAPTERS}"`,
-    '',
-    ...imports,
-    '',
+    `// Default: ${DEFAULT_PREBID_ADAPTERS_DESCRIPTION}`,
   ].join('\n');
+  const content = imports.length === 0 ? `${header}\n` : `${header}\n\n${imports.join('\n')}\n`;
 
   fs.writeFileSync(ADAPTERS_FILE, content);
 

crates/js/lib/src/integrations/prebid/_adapters.generated.ts

@@ -3,6 +3,4 @@
 // Controls which Prebid.js bid adapters are included in the bundle.
 // Set the TSJS_PREBID_ADAPTERS environment variable to a comma-separated list
 // of adapter names (e.g. "rubicon,appnexus,openx") before building.
-// Default: "rubicon"
-
-import 'prebid.js/modules/rubiconBidAdapter.js';
+// Default: no adapters

crates/trusted-server-core/src/auction/orchestrator.rs

@@ -12,6 +12,44 @@ use super::config::AuctionConfig;
 use super::provider::AuctionProvider;
 use super::types::{AuctionContext, AuctionRequest, AuctionResponse, Bid, BidStatus};
 
+const PROVIDER_ERROR_MESSAGE_CHARS: usize = 500;
+
+pub(crate) const ERROR_TYPE_HTTP_STATUS: &str = "http_status";
+const ERROR_TYPE_PARSE_RESPONSE: &str = "parse_response";
+const ERROR_TYPE_LAUNCH_FAILED: &str = "launch_failed";
+
+// SECURITY: the returned string is included verbatim (truncated to
+// PROVIDER_ERROR_MESSAGE_CHARS) in the public /auction response via
+// ProviderSummary.metadata["message"]. Providers MUST NOT interpolate
+// upstream-controlled content (response bodies, parse errors, headers) into
+// their TrustedServerError::*.message fields. Use static text and log details
+// server-side with `log::warn!` instead.
+fn provider_error_message(error: &Report<TrustedServerError>) -> String {
+    error
+        .current_context()
+        .to_string()
+        .chars()
+        .take(PROVIDER_ERROR_MESSAGE_CHARS)
+        .collect()
+}
+
+fn provider_error_response(
+    provider_name: &str,
+    response_time_ms: u64,
+    error_type: &str,
+    error: &Report<TrustedServerError>,
+) -> AuctionResponse {
+    AuctionResponse::error(provider_name, response_time_ms)
+        .with_metadata("error_type", serde_json::json!(error_type))
+        .with_metadata("message", serde_json::json!(provider_error_message(error)))
+}
+
+fn provider_launch_failed_response(provider_name: &str, response_time_ms: u64) -> AuctionResponse {
+    AuctionResponse::error(provider_name, response_time_ms)
+        .with_metadata("error_type", serde_json::json!(ERROR_TYPE_LAUNCH_FAILED))
+        .with_metadata("message", serde_json::json!("Provider launch failed"))
+}
+
 /// Compute the remaining time budget from a deadline.
 ///
 /// Returns the number of milliseconds left before `timeout_ms` is exceeded,
@@ -252,6 +290,7 @@ impl AuctionOrchestrator {
         let mut backend_to_provider: HashMap<String, (&str, Instant, &dyn AuctionProvider)> =
             HashMap::new();
         let mut pending_requests: Vec<PendingRequest> = Vec::new();
+        let mut responses = Vec::new();
 
         for provider_name in provider_names {
             let provider = match self.providers.get(provider_name) {
@@ -331,11 +370,16 @@ impl AuctionOrchestrator {
                     );
                 }
                 Err(e) => {
+                    let response_time_ms = start_time.elapsed().as_millis() as u64;
                     log::warn!(
                         "Provider '{}' failed to launch request: {:?}",
                         provider.provider_name(),
                         e
                     );
+                    responses.push(provider_launch_failed_response(
+                        provider.provider_name(),
+                        response_time_ms,
+                    ));
                 }
             }
         }
@@ -357,7 +401,6 @@ impl AuctionOrchestrator {
         // transport timeout fires). Hard deadline enforcement therefore depends
         // on every backend's `first_byte_timeout` being set to at most the
         // remaining auction budget — which Phase 1 above guarantees.
-        let mut responses = Vec::new();
         let mut remaining = pending_requests;
 
         while !remaining.is_empty() {
@@ -397,8 +440,12 @@ impl AuctionOrchestrator {
                                     provider_name,
                                     e
                                 );
-                                responses
-                                    .push(AuctionResponse::error(provider_name, response_time_ms));
+                                responses.push(provider_error_response(
+                                    provider_name,
+                                    response_time_ms,
+                                    ERROR_TYPE_PARSE_RESPONSE,
+                                    &e,
+                                ));
                             }
                         }
                     } else {
@@ -602,9 +649,11 @@ mod tests {
     use crate::auction::config::AuctionConfig;
     use crate::auction::test_support::create_test_auction_context;
     use crate::auction::types::{
-        AdFormat, AdSlot, AuctionRequest, Bid, MediaType, PublisherInfo, UserInfo,
+        AdFormat, AdSlot, AuctionRequest, Bid, BidStatus, MediaType, PublisherInfo, UserInfo,
     };
+    use crate::error::TrustedServerError;
     use crate::test_support::tests::crate_test_settings_str;
+    use error_stack::Report;
     use fastly::Request;
     use std::collections::{HashMap, HashSet};
 
@@ -657,6 +706,81 @@ mod tests {
         crate::settings::Settings::from_toml(&settings_str).expect("should parse test settings")
     }
 
+    #[test]
+    fn provider_error_response_includes_diagnostic_metadata() {
+        let error = Report::new(TrustedServerError::Auction {
+            message: "parse failed".to_string(),
+        })
+        .attach("internal/source.rs:12:34");
+
+        let response =
+            super::provider_error_response("prebid", 37, super::ERROR_TYPE_PARSE_RESPONSE, &error);
+
+        assert_eq!(
+            response.status,
+            BidStatus::Error,
+            "should mark diagnostic provider responses as errors"
+        );
+        assert_eq!(
+            response.metadata["error_type"],
+            serde_json::json!("parse_response"),
+            "should include the provider error classification"
+        );
+
+        let message = response.metadata["message"]
+            .as_str()
+            .expect("should include provider error message");
+        assert!(
+            message.contains("parse failed"),
+            "should include user-safe diagnostic detail"
+        );
+        assert!(
+            !message.contains("internal/source.rs"),
+            "should not include attached internal details"
+        );
+    }
+
+    #[test]
+    fn launch_failed_response_has_safe_static_message() {
+        let response = super::provider_launch_failed_response("prebid", 58);
+
+        assert_eq!(
+            response.status,
+            BidStatus::Error,
+            "should mark launch failures as errors"
+        );
+        assert_eq!(
+            response.metadata["error_type"],
+            serde_json::json!("launch_failed"),
+            "should include launch_failed classification"
+        );
+        assert_eq!(
+            response.metadata["message"],
+            serde_json::json!("Provider launch failed"),
+            "should use a safe, stable public launch failure message"
+        );
+    }
+
+    #[test]
+    fn provider_error_message_truncates_user_safe_context() {
+        let long_message = "x".repeat(super::PROVIDER_ERROR_MESSAGE_CHARS + 100);
+        let error = Report::new(TrustedServerError::Auction {
+            message: long_message,
+        });
+
+        let message = super::provider_error_message(&error);
+
+        assert_eq!(
+            message.chars().count(),
+            super::PROVIDER_ERROR_MESSAGE_CHARS,
+            "should cap provider error messages"
+        );
+        assert!(
+            message.starts_with("Auction error: "),
+            "should preserve the current context display text"
+        );
+    }
+
     #[test]
     fn filters_winning_bids_below_floor() {
         let orchestrator = AuctionOrchestrator::new(AuctionConfig::default());