From 354bdade75a88056561693449fc9347c0a904e9f Mon Sep 17 00:00:00 2001
From: Daniel Vigovszky <daniel.vigovszky@gmail.com>
Date: Wed, 5 Apr 2023 11:08:56 +0200
Subject: [PATCH 1/2] Log a warning in case of fatal errors

---
 zio-http/src/main/scala/zio/http/Server.scala       | 13 ++++++++++++-
 .../http/netty/server/ServerInboundHandler.scala    | 10 +++++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/zio-http/src/main/scala/zio/http/Server.scala b/zio-http/src/main/scala/zio/http/Server.scala
index 1e1448423c..d3ede32fcb 100644
--- a/zio-http/src/main/scala/zio/http/Server.scala
+++ b/zio-http/src/main/scala/zio/http/Server.scala
@@ -55,6 +55,7 @@ object Server {
     responseCompression: Option[ResponseCompressionConfig],
     objectAggregator: Int,
     maxHeaderSize: Int,
+    logWarningOnFatalError: Boolean,
   ) {
     self =>
     def useAggregator: Boolean = objectAggregator >= 0
@@ -102,6 +103,12 @@ object Server {
      */
     def keepAlive(enable: Boolean): Config = self.copy(keepAlive = enable)
 
+    /**
+     * Log a warning in case of fatal errors when an error response cannot be
+     * sent back to the client
+     */
+    def logWarningOnFatalError(enable: Boolean): Config = self.copy(logWarningOnFatalError = enable)
+
     /**
      * Configure the server to use HttpObjectAggregator with the specified max
      * size of the aggregated content.
@@ -159,7 +166,8 @@ object Server {
         Decompression.config.nested("request-decompression").withDefault(Config.default.requestDecompression) ++
         ResponseCompressionConfig.config.nested("response-compression").optional ++
         zio.Config.int("max-aggregated-request-size").withDefault(Config.default.objectAggregator) ++
-        zio.Config.int("max-header-size").withDefault(Config.default.maxHeaderSize)
+        zio.Config.int("max-header-size").withDefault(Config.default.maxHeaderSize) ++
+        zio.Config.boolean("log-warning-on-fatal-error").withDefault(Config.default.logWarningOnFatalError)
     }.map {
       case (
             sslConfig,
@@ -173,6 +181,7 @@ object Server {
             responseCompression,
             objectAggregator,
             maxHeaderSize,
+            logWarningOnFatalError,
           ) =>
         Config(
           sslConfig = sslConfig,
@@ -185,6 +194,7 @@ object Server {
           responseCompression = responseCompression,
           objectAggregator = objectAggregator,
           maxHeaderSize = maxHeaderSize,
+          logWarningOnFatalError = logWarningOnFatalError,
         )
     }
 
@@ -199,6 +209,7 @@ object Server {
       responseCompression = None,
       objectAggregator = 1024 * 100,
       maxHeaderSize = 8192,
+      logWarningOnFatalError = true,
     )
 
     final case class ResponseCompressionConfig(
diff --git a/zio-http/src/main/scala/zio/http/netty/server/ServerInboundHandler.scala b/zio-http/src/main/scala/zio/http/netty/server/ServerInboundHandler.scala
index ea29c1b182..075f55706c 100644
--- a/zio-http/src/main/scala/zio/http/netty/server/ServerInboundHandler.scala
+++ b/zio-http/src/main/scala/zio/http/netty/server/ServerInboundHandler.scala
@@ -128,7 +128,15 @@ private[zio] final case class ServerInboundHandler(
           runtime.run(ctx, () => {}) {
             // We cannot return the generated response from here, but still calling the handler for its side effect
             // for example logging.
-            app.runServerErrorOrNull(Cause.die(t)).unit
+            app
+              .runServerErrorOrNull(Cause.die(t))
+              .tap { response =>
+                if (config.logWarningOnFatalError)
+                  ZIO.logWarningCause(s"Fatal exception in Netty, cannot send error response $response", Cause.die(t))
+                else
+                  ZIO.unit
+              }
+              .unit
           }
         }
         super.exceptionCaught(ctx, t)

From 5cbf32dec2a2d27c2bb01b59f9044d6f0e8ff003 Mon Sep 17 00:00:00 2001
From: Daniel Vigovszky <daniel.vigovszky@gmail.com>
Date: Sun, 9 Apr 2023 12:35:19 +0200
Subject: [PATCH 2/2] Format

---
 zio-http/src/main/scala/zio/http/Server.scala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/zio-http/src/main/scala/zio/http/Server.scala b/zio-http/src/main/scala/zio/http/Server.scala
index 73fc0efbed..0dc7dd41a5 100644
--- a/zio-http/src/main/scala/zio/http/Server.scala
+++ b/zio-http/src/main/scala/zio/http/Server.scala
@@ -103,7 +103,7 @@ object Server {
      */
     def logWarningOnFatalError(enable: Boolean): Config = self.copy(logWarningOnFatalError = enable)
 
-    /**     
+    /**
      * Configure the server to use `maxHeaderSize` value when encode/decode
      * headers.
      */
@@ -153,7 +153,7 @@ object Server {
         zio.Config.boolean("accept-continue").withDefault(Config.default.acceptContinue) ++
         zio.Config.boolean("keep-alive").withDefault(Config.default.keepAlive) ++
         Decompression.config.nested("request-decompression").withDefault(Config.default.requestDecompression) ++
-        ResponseCompressionConfig.config.nested("response-compression").optional ++        
+        ResponseCompressionConfig.config.nested("response-compression").optional ++
         RequestStreaming.config.nested("request-streaming").withDefault(Config.default.requestStreaming) ++
         zio.Config.int("max-header-size").withDefault(Config.default.maxHeaderSize) ++
         zio.Config.boolean("log-warning-on-fatal-error").withDefault(Config.default.logWarningOnFatalError)