Feature - add timestamp to metric telemetry tracking

src/Arcus.Observability.Telemetry.Core/ContextProperties.cs

@@ -60,6 +60,7 @@ public static class MetricTracking
         {
             public const string MetricName = "MetricName";
             public const string MetricValue = "MetricValue";
+            public const string Timestamp = "Timestamp";
         }
     }
 }

src/Arcus.Observability.Telemetry.Core/Extensions/ILoggerExtensions.cs

@@ -80,7 +80,8 @@ public static class ILoggerExtensions
         private const string MetricFormat =
             MessagePrefixes.Metric + " {" 
             + ContextProperties.MetricTracking.MetricName + "}: {" 
-            + ContextProperties.MetricTracking.MetricValue 
+            + ContextProperties.MetricTracking.MetricValue + "} at {"
+            + ContextProperties.MetricTracking.Timestamp
             + "} (Context: {@" + ContextProperties.EventTracking.EventContext + "})";
 
         /// <summary>
@@ -669,7 +670,25 @@ public static void LogMetric(this ILogger logger, string name, double value, Dic
 
             context = context ?? new Dictionary<string, object>();
 
-            logger.LogInformation(MetricFormat, name, value, context);
+            LogMetric(logger, name, value, DateTimeOffset.UtcNow, context);
+        }
+
+        /// <summary>
+        ///     Logs a custom metric
+        /// </summary>
+        /// <param name="logger">Logger to use</param>
+        /// <param name="name">Name of the metric</param>
+        /// <param name="value">Value of the metric</param>
+        /// <param name="timestamp">Timestamp of the metric</param>
+        /// <param name="context">Context that provides more insights on the event that occured</param>
+        public static void LogMetric(this ILogger logger, string name, double value, DateTimeOffset timestamp, Dictionary<string, object> context = null)
+        {
+            Guard.NotNull(logger, nameof(logger));
+            Guard.NotNullOrWhitespace(name, nameof(name));
+
+            context = context ?? new Dictionary<string, object>();
+
+            logger.LogInformation(MetricFormat, name, value, timestamp.ToString(CultureInfo.InvariantCulture), context);
         }
 
         /// <summary>

src/Arcus.Observability.Telemetry.Serilog.Sinks.ApplicationInsights/Converters/MetricTelemetryConverter.cs

@@ -21,8 +21,13 @@ protected override MetricTelemetry CreateTelemetryEntry(LogEvent logEvent, IForm
         {
             var metricName = logEvent.Properties.GetAsRawString(ContextProperties.MetricTracking.MetricName);
             var metricValue = logEvent.Properties.GetAsDouble(ContextProperties.MetricTracking.MetricValue);
+            var timestamp = logEvent.Properties.GetAsDateTimeOffset(ContextProperties.MetricTracking.Timestamp);
+
+            var metricTelemetry = new MetricTelemetry(metricName, metricValue)
+            {
+                Timestamp = timestamp
+            };
 
-            var metricTelemetry = new MetricTelemetry(metricName, metricValue);
             return metricTelemetry;
         }
 
@@ -34,6 +39,7 @@ protected override void RemoveIntermediaryProperties(LogEvent logEvent)
         {
             logEvent.RemovePropertyIfPresent(ContextProperties.MetricTracking.MetricName);
             logEvent.RemovePropertyIfPresent(ContextProperties.MetricTracking.MetricValue);
+            logEvent.RemovePropertyIfPresent(ContextProperties.MetricTracking.Timestamp);
         }
     }
 }

src/Arcus.Observability.Tests.Unit/Serilog/ApplicationInsightsTelemetryConverterTests.cs

@@ -6,6 +6,7 @@
 using Arcus.Observability.Telemetry.Serilog.Sinks.ApplicationInsights;
 using Arcus.Observability.Telemetry.Serilog.Sinks.ApplicationInsights.Converters;
 using Bogus;
+using Bogus.DataSets;
 using Microsoft.ApplicationInsights.Channel;
 using Microsoft.ApplicationInsights.DataContracts;
 using Microsoft.AspNetCore.Http;
@@ -705,6 +706,7 @@ public void LogMetric_WithMetric_CreatesMetricTelemetry()
             // Arrange
             const string metricName = "Request stream";
             const double metricValue = 0.13;
+            var timestamp = DateTimeOffset.UtcNow;
             var spySink = new InMemoryLogSink();
             string operationId = $"operation-id-{Guid.NewGuid()}";
             ILogger logger = CreateLogger(spySink, config => config.Enrich.WithProperty(ContextProperties.Correlation.OperationId, operationId));
@@ -713,7 +715,7 @@ public void LogMetric_WithMetric_CreatesMetricTelemetry()
             {
                 ["Capacity"] = "0.45"
             };
-            logger.LogMetric(metricName, metricValue, telemetryContext);
+            logger.LogMetric(metricName, metricValue, timestamp, telemetryContext);
             LogEvent logEvent = Assert.Single(spySink.CurrentLogEmits);
             Assert.NotNull(logEvent);
 
@@ -725,12 +727,14 @@ public void LogMetric_WithMetric_CreatesMetricTelemetry()
             // Assert
             AssertDoesNotContainLogProperty(logEvent, MetricTracking.MetricName);
             AssertDoesNotContainLogProperty(logEvent, MetricTracking.MetricValue);
+            AssertDoesNotContainLogProperty(logEvent, MetricTracking.Timestamp);
             AssertDoesNotContainLogProperty(logEvent, EventTracking.EventContext);
             Assert.Collection(telemetries, telemetry =>
             {
                 var metricTelemetry = Assert.IsType<MetricTelemetry>(telemetry);
                 Assert.Equal(metricName, metricTelemetry.Name);
                 Assert.Equal(metricValue, metricTelemetry.Sum);
+                Assert.Equal(TruncateToSeconds(timestamp), metricTelemetry.Timestamp);
                 AssertOperationContext(metricTelemetry, operationId);
 
                 AssertContainsTelemetryProperty(metricTelemetry, "Capacity", "0.45");

src/Arcus.Observability.Tests.Unit/Telemetry/ILoggerExtensionsTests.cs

@@ -37,6 +37,26 @@ public void LogMetric_ValidArguments_Succeeds()
             Assert.Contains(metricValue.ToString(CultureInfo.InvariantCulture), logMessage);
         }
 
+        [Fact]
+        public void LogMetric_ValidArgumentsWithTimestamp_Succeeds()
+        {
+            // Arrange
+            var logger = new TestLogger();
+            string metricName = _bogusGenerator.Name.FullName();
+            double metricValue = _bogusGenerator.Random.Double();
+            DateTimeOffset timestamp = _bogusGenerator.Date.RecentOffset();
+
+            // Act
+            logger.LogMetric(metricName, metricValue, timestamp);
+
+            // Assert
+            var logMessage = logger.WrittenMessage;
+            Assert.StartsWith(MessagePrefixes.Metric, logMessage);
+            Assert.Contains(metricName, logMessage);
+            Assert.Contains(metricValue.ToString(CultureInfo.InvariantCulture), logMessage);
+            Assert.Contains(timestamp.ToString(CultureInfo.InvariantCulture), logMessage);
+        }
+
         [Fact]
         public void LogMetric_NoMetricNameWasSpecified_ThrowsException()
         {