Improve elasticsearch client exceptions default Message by trying to read the server error reason and making it part of the exception message

Author: Mpdreamz

src/Elasticsearch.Net/Responses/ElasticsearchResponse.cs

@@ -8,9 +8,18 @@ namespace Elasticsearch.Net
 	/// <summary>
 	/// A response from elasticsearch including details about the request/response life cycle
 	/// </summary>
-	public class ElasticsearchResponseBase : IApiCallDetails, IElasticsearchResponse
+	public abstract class ElasticsearchResponseBase : IApiCallDetails, IElasticsearchResponse
 	{
 		public IApiCallDetails ApiCall { get; set; }
+
+		bool IElasticsearchResponse.TryGetServerErrorReason(out string reason) => this.TryGetServerErrorReason(out reason);
+
+		protected virtual bool TryGetServerErrorReason(out string reason)
+		{
+			reason = null;
+			return false;
+		}
+
 		//ignored
 		List<Audit> IApiCallDetails.AuditTrail { get; set; }
 
@@ -26,12 +35,15 @@ public class ElasticsearchResponseBase : IApiCallDetails, IElasticsearchResponse
 
 		/// <summary>The raw byte request message body, only set when DisableDirectStreaming() is set on Connection configuration</summary>
 		public byte[] RequestBodyInBytes => this.ApiCall.RequestBodyInBytes;
+
 		/// <summary>The raw byte response message body, only set when DisableDirectStreaming() is set on Connection configuration</summary>
 		public byte[] ResponseBodyInBytes => this.ApiCall.ResponseBodyInBytes;
 
 		public string DebugInformation => this.ApiCall.DebugInformation;
 
 		public override string ToString() => this.ApiCall.ToString();
+
+
 	}
 
 	/// <summary>

src/Elasticsearch.Net/Responses/IElasticsearchResponse.cs

@@ -10,5 +10,7 @@ public interface IElasticsearchResponse
 		/// Sets and returns the <see cref="IApiCallDetails"/> diagnostic information
 		/// </summary>
 		IApiCallDetails ApiCall { get; set; }
+
+		bool TryGetServerErrorReason(out string reason);
 	}
 }

src/Elasticsearch.Net/Responses/Special/BytesResponse.cs

@@ -16,5 +16,13 @@ public bool TryGetServerError(out ServerError serverError)
 				serverError = ServerError.Create(stream);
 			return true;
 		}
+
+		protected override bool TryGetServerErrorReason(out string reason)
+		{
+			reason = null;
+			if (!this.TryGetServerError(out var serverError)) return false;
+			reason = serverError?.Error?.Reason;
+			return !reason.IsNullOrEmpty();
+		}
 	}
 }

src/Elasticsearch.Net/Responses/Special/StringResponse.cs

@@ -16,5 +16,13 @@ public bool TryGetServerError(out ServerError serverError)
 				serverError = ServerError.Create(stream);
 			return true;
 		}
+
+		protected override bool TryGetServerErrorReason(out string reason)
+		{
+			reason = null;
+			if (!this.TryGetServerError(out var serverError)) return false;
+			reason = serverError?.Error?.Reason;
+			return !reason.IsNullOrEmpty();
+		}
 	}
 }

src/Elasticsearch.Net/Responses/Special/VoidResponse.cs

@@ -5,5 +5,6 @@ namespace Elasticsearch.Net
 	public class VoidResponse : ElasticsearchResponse<VoidResponse.VoidBody>
 	{
 		public class VoidBody { }
+
 	}
 }

src/Elasticsearch.Net/Transport/Pipeline/IRequestPipeline.cs

@@ -53,6 +53,7 @@ void BadResponse<TResponse>(ref TResponse response, IApiCallDetails callDetails,
 
 		void AuditCancellationRequested();
 
-		ElasticsearchClientException CreateClientException(IApiCallDetails response, RequestData data, List<PipelineException> seenExceptions);
+		ElasticsearchClientException CreateClientException<TResponse>(TResponse response, RequestData data, List<PipelineException> seenExceptions)
+			where TResponse : class, IElasticsearchResponse, new();
 	}
 }

src/Elasticsearch.Net/Transport/Pipeline/RequestPipeline.cs

@@ -482,12 +482,16 @@ public void BadResponse<TResponse>(ref TResponse response, IApiCallDetails callD
 			response.ApiCall.AuditTrail = this.AuditTrail;
 		}
 
-		public ElasticsearchClientException CreateClientException(IApiCallDetails callDetails, RequestData data, List<PipelineException> pipelineExceptions)
+		public ElasticsearchClientException CreateClientException<TResponse>(TResponse response, RequestData data, List<PipelineException> pipelineExceptions)
+			where TResponse : class, IElasticsearchResponse, new()
 		{
+			var callDetails = response.ApiCall;
 			if (callDetails.Success) return null;
 			var innerException = pipelineExceptions.HasAny() ? new AggregateException(pipelineExceptions) : callDetails?.OriginalException;
 
 			var exceptionMessage = innerException?.Message ?? $"Request failed to execute";
+			if (response.TryGetServerErrorReason(out var reason))
+				exceptionMessage += $". Error: {reason}";
 
 			var pipelineFailure = data.OnFailurePipelineFailure;
 			if (pipelineExceptions.HasAny())

src/Elasticsearch.Net/Transport/Transport.cs

@@ -171,9 +171,8 @@ private TResponse FinalizeResponse<TResponse>(RequestData requestData, IRequestP
 				pipeline.ThrowNoNodesAttempted(requestData, seenExceptions);
 
 			var callDetails = GetMostRecentCallDetails(response, seenExceptions);
-			var clientException = pipeline.CreateClientException(callDetails, requestData, seenExceptions);
+			var clientException = pipeline.CreateClientException(response, requestData, seenExceptions);
 
-			//if (response?.ApiCall == null || !response.ApiCall.Success)
 			if (response?.ApiCall == null)
 				pipeline.BadResponse(ref response, callDetails, requestData, clientException);
 

src/Nest/CommonAbstractions/Response/ResponseBase.cs

@@ -55,6 +55,12 @@ public abstract class ResponseBase : IResponse
         [JsonIgnore]
 		IApiCallDetails IElasticsearchResponse.ApiCall { get => _originalApiCall; set => _originalApiCall = value; }
 
+		bool IElasticsearchResponse.TryGetServerErrorReason(out string reason)
+		{
+			reason = this.ServerError?.Error?.Reason;
+			return !reason.IsNullOrEmpty();
+		}
+
 		public ServerError ServerError
 		{
 			get

src/Tests/Reproduce/GithubIssue2985.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Linq;
+using Elasticsearch.Net;
+using FluentAssertions;
+using Nest;
+using Tests.Framework;
+using Tests.Framework.ManagedElasticsearch.Clusters;
+using Tests.Framework.MockData;
+using Xunit;
+
+namespace Tests.Reproduce
+{
+	public class GithubIssue2985 : IClusterFixture<WritableCluster>
+	{
+		private readonly WritableCluster _cluster;
+
+		public GithubIssue2985(WritableCluster cluster) => _cluster = cluster;
+
+		protected static string RandomString() => Guid.NewGuid().ToString("N").Substring(0, 8);
+
+		[I]
+		public void CanReadSingleOrMultipleCommonGramsCommonWordsItem()
+		{
+			var client = _cluster.Client;
+			var index = $"gh2985-{RandomString()}";
+			var response = client.CreateIndex(index, i=> i
+				.Settings(s=>s
+					.Analysis(a=>a
+						.Analyzers(an=>an
+							.Custom("custom", c=>c.Filters("ascii_folding").Tokenizer("standard"))
+						)
+					)
+				)
+			);
+			response.OriginalException.Should().NotBeNull().And.BeOfType<ElasticsearchClientException>();
+			response.OriginalException.Message.Should()
+				.Be("Request failed to execute. Error: Custom Analyzer [custom] failed to find filter under name [ascii_folding]");
+
+			client.DeleteIndex(index);
+		}
+	}
+}