Merge pull request #36 from tobiashein/add-correlation-id-from-response

Add correlation ID from HTTP response

Author: mo-esmp

src/Serilog.Enrichers.ClientInfo/Enrichers/CorrelationIdEnricher.cs

@@ -47,10 +47,27 @@ public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
             return;
         }
 
-        var header = httpContext.Request.Headers[_headerKey].ToString();
-        var correlationId = !string.IsNullOrWhiteSpace(header)
-            ? header
-            : (_addValueIfHeaderAbsence ? Guid.NewGuid().ToString() : null);
+        var requestHeader = httpContext.Request.Headers[_headerKey];
+        var responseHeader = httpContext.Response.Headers[_headerKey];
+        
+        string correlationId;
+        
+        if (!string.IsNullOrWhiteSpace(requestHeader))
+        {
+            correlationId = requestHeader;
+        }
+        else if (!string.IsNullOrWhiteSpace(responseHeader))
+        {
+            correlationId = responseHeader;
+        }
+        else if (_addValueIfHeaderAbsence)
+        {
+            correlationId = Guid.NewGuid().ToString();
+        }
+        else
+        {
+            correlationId = null;
+        }
 
         var correlationIdProperty = new LogEventProperty(PropertyName, new ScalarValue(correlationId));
         logEvent.AddOrUpdateProperty(correlationIdProperty);

test/Serilog.Enrichers.ClientInfo.Tests/CorrelationIdEnricherTests.cs

@@ -108,6 +108,54 @@ public void EnrichLogWithCorrelationId_WhenHttpRequestNotContainCorrelationHeade
         Assert.NotNull(evt.Properties[LogPropertyName].LiteralValue().ToString());
     }
 
+    [Fact]
+    public void EnrichLogWithCorrelationId_WhenHttpResponseContainsCorrelationIdHeader_ShouldCreateCorrelationIdProperty()
+    {
+        // Arrange
+        var correlationId = Guid.NewGuid().ToString();
+        _contextAccessor.HttpContext.Response.Headers.Add(HeaderKey, correlationId);
+        var correlationIdEnricher = new CorrelationIdEnricher(HeaderKey, false, _contextAccessor);
+
+        LogEvent evt = null;
+        var log = new LoggerConfiguration()
+            .Enrich.With(correlationIdEnricher)
+            .WriteTo.Sink(new DelegatingSink(e => evt = e))
+            .CreateLogger();
+
+        // Act
+        log.Information(@"Has a correlation id.");
+
+        // Assert
+        Assert.NotNull(evt);
+        Assert.True(evt.Properties.ContainsKey(LogPropertyName));
+        Assert.Equal(correlationId, evt.Properties[LogPropertyName].LiteralValue().ToString());
+    }
+
+    [Fact]
+    public void EnrichLogWithCorrelationId_WhenHttpRequestAndResponseContainCorrelationIdHeader_ShouldCreateCorrelationIdPropertyFromHttpRequest()
+    {
+        // Arrange
+        var requestCorrelationId = Guid.NewGuid().ToString();
+        var responseCorrelationId = Guid.NewGuid().ToString();
+        _contextAccessor.HttpContext.Request.Headers.Add(HeaderKey, requestCorrelationId);
+        _contextAccessor.HttpContext.Response.Headers.Add(HeaderKey, responseCorrelationId);
+        var correlationIdEnricher = new CorrelationIdEnricher(HeaderKey, false, _contextAccessor);
+
+        LogEvent evt = null;
+        var log = new LoggerConfiguration()
+            .Enrich.With(correlationIdEnricher)
+            .WriteTo.Sink(new DelegatingSink(e => evt = e))
+            .CreateLogger();
+
+        // Act
+        log.Information(@"Has a correlation id.");
+
+        // Assert
+        Assert.NotNull(evt);
+        Assert.True(evt.Properties.ContainsKey(LogPropertyName));
+        Assert.Equal(requestCorrelationId, evt.Properties[LogPropertyName].LiteralValue().ToString());
+    }
+
     [Fact]
     public void WithClientIp_ThenLoggerIsCalled_ShouldNotThrowException()
     {