Make sure the sink (and app) do not crash when the ES is unreachable …

…during the discovery of the version. (#359)

CHANGES.md

@@ -1,5 +1,8 @@
 ## Changelog
 
+8.3 
+ * Do not crash when ES is unreachable and the option `DetectElasticsearchVersion` is set to true.
+
 * Disable dot-escaping for field names, because ELK already supports dots in field names.
 * Support for explicitly setting `Options.TypeName` to `null` this will remove the 
   deprecated `_type` from the bulk payload being sent to Elastic. Earlier an exception was

global.json

@@ -1,5 +1,5 @@
 {
     "sdk": {
-        "version": "2.1.500"
+        "version": "2.1.807"
     }
 }

sample/Serilog.Sinks.Elasticsearch.Sample/Program.cs

@@ -41,7 +41,7 @@ static void Main(string[] args)
                     NumberOfReplicas = 1,
                     NumberOfShards = 2,
                     //BufferBaseFilename = "./buffer",
-                    RegisterTemplateFailure = RegisterTemplateRecovery.FailSink,
+                   // RegisterTemplateFailure = RegisterTemplateRecovery.FailSink,
                     FailureCallback = e => Console.WriteLine("Unable to submit event " + e.MessageTemplate),
                     EmitEventFailure = EmitEventFailureHandling.WriteToSelfLog |
                                        EmitEventFailureHandling.WriteToFailureSink |

src/Serilog.Sinks.Elasticsearch/Sinks/ElasticSearch/ElasticsearchSinkState.cs

@@ -242,17 +242,25 @@ public void DiscoverClusterVersion()
         {
             if (!_options.DetectElasticsearchVersion) return;
 
-            var response = _client.Cat.Nodes<StringResponse>(new CatNodesRequestParameters()
+            try
             {
-                Headers = new[] { "v" }
-            });
-            if (!response.Success) return;
 
-            _discoveredVersion = response.Body.Split(new[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries)
-                .FirstOrDefault();
+                var response = _client.Cat.Nodes<StringResponse>(new CatNodesRequestParameters()
+                {
+                    Headers = new[] { "v" }
+                });
+                if (!response.Success) return;
+
+                _discoveredVersion = response.Body.Split(new[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries)
+                    .FirstOrDefault();
 
-            if (_discoveredVersion?.StartsWith("7.") ?? false)
-                _options.TypeName = "_doc";
+                if (_discoveredVersion?.StartsWith("7.") ?? false)
+                    _options.TypeName = "_doc";
+            }
+            catch (Exception ex)
+            {
+                SelfLog.WriteLine("Failed to discover the cluster version. {0}", ex);
+            }
         }
     }
 }

test/Serilog.Sinks.Elasticsearch.Tests/ElasticsearchSinkTestsBase.cs

@@ -23,6 +23,7 @@ public abstract class ElasticsearchSinkTestsBase
         protected readonly ElasticsearchSinkOptions _options;
         protected List<string> _seenHttpPosts = new List<string>();
         protected List<int> _seenHttpHeads = new List<int>();
+        protected List<Tuple<Uri, int>> _seenHttpGets = new List<Tuple<Uri, int>>();
         protected List<Tuple<Uri, string>> _seenHttpPuts = new List<Tuple<Uri, string>>();
         private IElasticsearchSerializer _serializer;
 
@@ -32,10 +33,11 @@ protected ElasticsearchSinkTestsBase()
         {
             _seenHttpPosts = new List<string>();
             _seenHttpHeads = new List<int>();
+            _seenHttpGets = new List<Tuple<Uri,int>>();
             _seenHttpPuts = new List<Tuple<Uri, string>>();
 
             var connectionPool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
-            _connection = new ConnectionStub(_seenHttpPosts, _seenHttpHeads, _seenHttpPuts, () => _templateExistsReturnCode);
+            _connection = new ConnectionStub(_seenHttpPosts, _seenHttpHeads, _seenHttpPuts, _seenHttpGets, () => _templateExistsReturnCode);
             _serializer = JsonNetSerializer.Default(LowLevelRequestResponseSerializer.Instance, new ConnectionSettings(connectionPool, _connection));
 
             _options = new ElasticsearchSinkOptions(connectionPool)
@@ -119,19 +121,22 @@ public class ConnectionStub : InMemoryConnection
         {
             private Func<int> _templateExistReturnCode;
             private List<int> _seenHttpHeads;
+            private List<Tuple<Uri, int>> _seenHttpGets;
             private List<string> _seenHttpPosts;
             private List<Tuple<Uri, string>> _seenHttpPuts;
 
             public ConnectionStub(
                 List<string> _seenHttpPosts,
                 List<int> _seenHttpHeads,
                 List<Tuple<Uri, string>> _seenHttpPuts,
+                List<Tuple<Uri, int>> _seenHttpGets,
                 Func<int> templateExistReturnCode
                 )
             {
                 this._seenHttpPosts = _seenHttpPosts;
                 this._seenHttpHeads = _seenHttpHeads;
                 this._seenHttpPuts = _seenHttpPuts;
+                this._seenHttpGets = _seenHttpGets;
                 this._templateExistReturnCode = templateExistReturnCode;
             }
 
@@ -149,6 +154,9 @@ public override TReturn Request<TReturn>(RequestData requestData)
                     case HttpMethod.POST:
                         _seenHttpPosts.Add(Encoding.UTF8.GetString(ms.ToArray()));
                         break;
+                    case HttpMethod.GET:
+                        _seenHttpGets.Add(Tuple.Create(requestData.Uri, this._templateExistReturnCode()));
+                        break;
                     case HttpMethod.HEAD:
                         _seenHttpHeads.Add(this._templateExistReturnCode());
                         break;
@@ -172,6 +180,9 @@ public override async Task<TResponse> RequestAsync<TResponse>(RequestData reques
                     case HttpMethod.POST:
                         _seenHttpPosts.Add(Encoding.UTF8.GetString(ms.ToArray()));
                         break;
+                    case HttpMethod.GET:
+                        _seenHttpGets.Add(Tuple.Create(requestData.Uri, this._templateExistReturnCode()));
+                        break;
                     case HttpMethod.HEAD:
                         _seenHttpHeads.Add(this._templateExistReturnCode());
                         break;

test/Serilog.Sinks.Elasticsearch.Tests/Templating/DiscoverVersionHandlesUnavailableServerTests.cs

@@ -0,0 +1,45 @@
+using System;
+using System.IO;
+using System.Text;
+using FluentAssertions;
+using Xunit;
+using Serilog.Debugging;
+
+namespace Serilog.Sinks.Elasticsearch.Tests.Templating
+{
+    [Collection("isolation")]
+    public class DiscoverVersionHandlesUnavailableServerTests : ElasticsearchSinkTestsBase
+    {
+        [Fact]
+        public void Should_not_crash_when_server_is_unavaiable()
+        {
+            // If this crashes, the test will fail
+            CreateLoggerThatCrashes();
+        }
+
+        [Fact]
+        public void Should_write_error_to_self_log()
+        {
+            var selfLogMessages = new StringBuilder();
+            SelfLog.Enable(new StringWriter(selfLogMessages));
+
+            // Exception occurs on creation - should be logged
+            CreateLoggerThatCrashes();
+
+            var selfLogContents = selfLogMessages.ToString();
+            selfLogContents.Should().Contain("Failed to discover the cluster version");
+
+        }
+
+        private static ILogger CreateLoggerThatCrashes()
+        {
+            var loggerConfig = new LoggerConfiguration()
+                .WriteTo.Elasticsearch(new ElasticsearchSinkOptions(new Uri("http://localhost:9199"))
+                {
+                    DetectElasticsearchVersion = true
+                });
+
+            return loggerConfig.CreateLogger();
+        }
+    }
+}

test/Serilog.Sinks.Elasticsearch.Tests/Templating/DiscoverVersionTests.cs

@@ -0,0 +1,39 @@
+using System;
+using FluentAssertions;
+using Xunit;
+
+namespace Serilog.Sinks.Elasticsearch.Tests.Templating
+{
+    public class DiscoverVersionTests : ElasticsearchSinkTestsBase
+    {
+        private readonly Tuple<Uri,int> _templateGet;
+
+        public DiscoverVersionTests()
+        {
+            _options.DetectElasticsearchVersion = true;
+
+            var loggerConfig = new LoggerConfiguration()
+                .MinimumLevel.Debug()
+                .Enrich.WithMachineName()
+                .WriteTo.ColoredConsole()
+                .WriteTo.Elasticsearch(_options);
+
+            var logger = loggerConfig.CreateLogger();
+            using ((IDisposable) logger)
+            {
+                logger.Error("Test exception. Should not contain an embedded exception object.");
+            }
+
+            this._seenHttpGets.Should().NotBeNullOrEmpty().And.HaveCount(1);
+            _templateGet = this._seenHttpGets[0];
+        }
+
+
+        [Fact]
+        public void TemplatePutToCorrectUrl()
+        {
+            var uri = _templateGet.Item1;
+            uri.AbsolutePath.Should().Be("/_cat/nodes");
+        }
+    }
+}

test/Serilog.Sinks.Elasticsearch.Tests/Templating/SendsTemplateHandlesUnavailableServerTests.cs

@@ -11,7 +11,7 @@ namespace Serilog.Sinks.Elasticsearch.Tests.Templating
     public class SendsTemplateHandlesUnavailableServerTests : ElasticsearchSinkTestsBase
     {
         [Fact]
-        public void Should_not_crash_when_server_is_unavaiable()
+        public void Should_not_crash_when_server_is_unavailable()
         {
             // If this crashes, the test will fail
             CreateLoggerThatCrashes();