Added WithEnvironmentName enricher

README.md

@@ -27,5 +27,6 @@ The package includes:
 
  * `WithMachineName()` - adds `MachineName` based on either `%COMPUTERNAME%` (Windows) or `$HOSTNAME` (macOS, Linux)
  * `WithEnvironmentUserName()` - adds `EnvironmentUserName` based on `USERNAME` and `USERDOMAIN` (if available)
+ * `WithEnvironmentName()` - adds `EnvironmentName` based on `ASPNETCORE_ENVIRONMENT` or `DOTNET_ENVIRONMENT` (when both are available then 'ASPNETCORE_ENVIRONMENT' takes precedence, when none are available then the faalback value will be 'Production')
 
 Copyright © 2016 Serilog Contributors - Provided under the [Apache License, Version 2.0](http://apache.org/licenses/LICENSE-2.0.html).

src/Serilog.Enrichers.Environment/Enrichers/EnvironmentNameEnricher.cs

@@ -0,0 +1,73 @@
+// Copyright 2013-2018 Serilog Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+using Serilog.Core;
+using Serilog.Events;
+using System.Runtime.CompilerServices;
+
+namespace Serilog.Enrichers
+{
+    /// <summary>
+    /// Enriches log events with a EnvironmentName property containing the value of the ASPNETCORE_ENVIRONMENT or DOTNET_ENVIRONMENT environment variable.
+    /// </summary>
+    public class EnvironmentNameEnricher : ILogEventEnricher
+    {
+        LogEventProperty _cachedProperty;
+
+        /// <summary>
+        /// The property name added to enriched log events.
+        /// </summary>
+        public const string EnvironmentNamePropertyName = "EnvironmentName";
+
+        /// <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)
+        {
+            logEvent.AddPropertyIfAbsent(GetLogEventProperty(propertyFactory));
+        }
+
+        private LogEventProperty GetLogEventProperty(ILogEventPropertyFactory propertyFactory)
+        {
+            // Don't care about thread-safety, in the worst case the field gets overwritten and one
+            // property will be GCed
+            if (_cachedProperty == null)
+                _cachedProperty = CreateProperty(propertyFactory);
+
+            return _cachedProperty;
+        }
+
+        // Qualify as uncommon-path
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private static LogEventProperty CreateProperty(ILogEventPropertyFactory propertyFactory)
+        {
+            var environmentName = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
+
+            if (string.IsNullOrWhiteSpace(environmentName))
+            {
+                environmentName = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
+            }
+
+            if (string.IsNullOrWhiteSpace(environmentName))
+            {
+                environmentName = "Production";
+            }
+
+            return propertyFactory.CreateProperty(EnvironmentNamePropertyName, environmentName);
+        }
+    }
+}

src/Serilog.Enrichers.Environment/EnvironmentLoggerConfigurationExtensions.cs

@@ -23,7 +23,19 @@ namespace Serilog
     /// capabilities.
     /// </summary>
     public static class EnvironmentLoggerConfigurationExtensions
-    { 
+    {
+        /// <summary>
+        /// Enrich log events with a EnvironmentName property containing the value of the ASPNETCORE_ENVIRONMENT or DOTNET_ENVIRONMENT environment variable.
+        /// </summary>
+        /// <param name="enrichmentConfiguration">Logger enrichment configuration.</param>
+        /// <returns>Configuration object allowing method chaining.</returns>
+        public static LoggerConfiguration WithEnvironmentName(
+           this LoggerEnrichmentConfiguration enrichmentConfiguration)
+        {
+            if (enrichmentConfiguration == null) throw new ArgumentNullException(nameof(enrichmentConfiguration));
+            return enrichmentConfiguration.With<EnvironmentNameEnricher>();
+        }
+
         /// <summary>
         /// Enrich log events with a MachineName property containing the current <see cref="Environment.MachineName"/>.
         /// </summary>

test/Serilog.Enrichers.Environment.Tests/Enrichers/EnvironmentEnvironmenNameEnricherTests.cs

@@ -0,0 +1,24 @@
+using Serilog.Events;
+using Serilog.Tests.Support;
+using Xunit;
+
+namespace Serilog.Tests.Enrichers
+{
+    public class EnvironmentEnvironmenNameEnricherTests
+    {
+        [Fact]
+        public void EnvironmentNameEnricherIsApplied()
+        {
+            LogEvent evt = null;
+            var log = new LoggerConfiguration()
+                .Enrich.WithEnvironmentName()
+                .WriteTo.Sink(new DelegatingSink(e => evt = e))
+                .CreateLogger();
+
+            log.Information(@"Has an EnvironmenName property with the value of the DOTNET_ENVIRONMENT or ASPNETCORE_ENVIRONMENT environment variable.");
+
+            Assert.NotNull(evt);
+            Assert.NotEmpty((string)evt.Properties["EnvironmentName"].LiteralValue());
+        }
+    }
+}