FEAT: add Kubernetes enricher

src/Arcus.Observability.Telemetry.Serilog/Arcus.Observability.Telemetry.Serilog.csproj

@@ -22,4 +22,4 @@
     <PackageReference Include="Serilog" Version="2.9.0" />
   </ItemGroup>
 
-</Project>
+</Project>

src/Arcus.Observability.Telemetry.Serilog/KubernetesEnricher.cs

@@ -0,0 +1,34 @@
+using System;
+using Serilog.Core;
+using Serilog.Events;
+
+namespace Arcus.Observability.Telemetry.Serilog
+{
+    /// <summary>
+    /// Enrichment on log events that automatically adds Kubernetes information from the environment.
+    /// </summary>
+    public class KubernetesEnricher : ILogEventEnricher
+    {
+        /// <summary>
+        /// Enrich the log event.
+        /// </summary>
+        /// <param name="logEvent">The log event to enrich.</param>
+        /// <param name="propertyFactory">Factory for creating new properties to add to the event.</param>
+        public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
+        {
+            EnrichEnvironmentVariable("KUBERNETES_NODE_NAME", logEvent, propertyFactory);
+            EnrichEnvironmentVariable("KUBERNETES_POD_NAME", logEvent, propertyFactory);
+            EnrichEnvironmentVariable("KUBERNETES_NAMESPACE", logEvent, propertyFactory);
+        }
+
+        private static void EnrichEnvironmentVariable(string name, LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
+        {
+            string value = Environment.GetEnvironmentVariable(name, EnvironmentVariableTarget.Process);
+            if (!String.IsNullOrWhiteSpace(value))
+            {
+                LogEventProperty property = propertyFactory.CreateProperty(name, value);
+                logEvent.AddPropertyIfAbsent(property);
+            }
+        }
+    }
+}

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

@@ -0,0 +1,56 @@
+using System;
+using Arcus.Observability.Telemetry.Serilog;
+using Serilog;
+using Serilog.Events;
+using Xunit;
+
+namespace Arcus.Observability.Tests.Unit.Telemetry
+{
+    [Trait("Category", "Unit")]
+    public class KubernetesEnricherTests
+    {
+        [Fact]
+        public void LogEvent_WithKubernetesEnricher_HasEnvironmentInformation()
+        {
+            // Arrange
+            const string kubernetesNodeName = "KUBERNETES_NODE_NAME",
+                         kubernetesPodName = "KUBERNETES_POD_NAME",
+                         kubernetesNamespace = "KUBERNETES_NAMESPACE";
+
+            string nodeName = $"node-{Guid.NewGuid()}";
+            string podName = $"pod-{Guid.NewGuid()}";
+            string @namespace = $"namespace-{Guid.NewGuid()}";
+
+            var spy = new InMemoryLogSink();
+            var logger = new LoggerConfiguration()
+                .Enrich.With<KubernetesEnricher>()
+                .WriteTo.Sink(spy)
+                .CreateLogger();
+
+            using (TemporaryEnvironmentVariable.Create(kubernetesNodeName, nodeName))
+            using (TemporaryEnvironmentVariable.Create(kubernetesPodName, podName))
+            using (TemporaryEnvironmentVariable.Create(kubernetesNamespace, @namespace))
+            {
+                // Act
+                logger.Information("This log event should be enriched with Kubernetes information");
+            }
+
+            // Assert
+            LogEvent logEvent = Assert.Single(spy.CurrentLogEmits);
+            Assert.NotNull(logEvent);
+
+            ContainsLogProperty(logEvent, kubernetesNodeName, nodeName);
+            ContainsLogProperty(logEvent, kubernetesPodName, podName);
+            ContainsLogProperty(logEvent, kubernetesNamespace, @namespace);
+        }
+
+        private static void ContainsLogProperty(LogEvent logEvent, string name, string expectedValue)
+        {
+            (string key, LogEventPropertyValue actual) = 
+                Assert.Single(logEvent.Properties, prop => prop.Key == name);
+
+            string actualValue = actual.ToString().Trim('\"');
+            Assert.Equal(expectedValue, actualValue);
+        }
+    }
+}

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

@@ -0,0 +1,38 @@
+using System;
+using GuardNet;
+
+namespace Arcus.Observability.Tests.Unit.Telemetry 
+{
+    /// <summary>
+    /// Represents a temporary environment variable that gets removed when the model gets disposed.
+    /// </summary>
+    public class TemporaryEnvironmentVariable : IDisposable
+    {
+        private readonly string _name;
+
+        private TemporaryEnvironmentVariable(string name)
+        {
+            Guard.NotNullOrWhitespace(name, nameof(name));
+
+            _name = name;
+        }
+
+        public static TemporaryEnvironmentVariable Create(string name, string value)
+        {
+            Guard.NotNullOrWhitespace(name, nameof(name));
+            Guard.NotNullOrWhitespace(value, nameof(value));
+
+            Environment.SetEnvironmentVariable(name, value, EnvironmentVariableTarget.Process);
+            return new TemporaryEnvironmentVariable(name);
+        }
+
+
+        /// <summary>
+        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
+        /// </summary>
+        public void Dispose()
+        {
+            Environment.SetEnvironmentVariable(_name, value: null, EnvironmentVariableTarget.Process);
+        }
+    }
+}