Exposing unique slot name and changing host ID and metrics to use the new setting

Author: fabiocav

src/WebJobs.Script.WebHost/Diagnostics/MetricsEventManager.cs

@@ -31,7 +31,7 @@ public class MetricsEventManager : IDisposable
         public MetricsEventManager(ScriptSettingsManager settingsManager, IEventGenerator generator, int functionActivityFlushIntervalSeconds, int metricsFlushIntervalMS = DefaultFlushIntervalMS)
         {
             // we read these in the ctor (not static ctor) since it can change on the fly
-            appName = GetNormalizedString(settingsManager.AzureWebsiteDefaultSubdomain);
+            appName = GetNormalizedString(settingsManager.AzureWebsiteUniqueSlotName);
             subscriptionId = Utility.GetSubscriptionId() ?? string.Empty;
 
             _eventGenerator = generator;

src/WebJobs.Script.WebHost/Diagnostics/SystemTraceWriter.cs

@@ -22,7 +22,7 @@ public SystemTraceWriter(TraceLevel level) : this(new EventGenerator(), ScriptSe
         public SystemTraceWriter(IEventGenerator eventGenerator, ScriptSettingsManager settingsManager, TraceLevel level) : base(level)
         {
             _settingsManager = settingsManager;
-            _appName = _settingsManager.AzureWebsiteDefaultSubdomain;
+            _appName = _settingsManager.AzureWebsiteUniqueSlotName;
             _subscriptionId = Utility.GetSubscriptionId();
             _eventGenerator = eventGenerator;
         }

src/WebJobs.Script/Config/ScriptSettingsManager.cs

@@ -48,6 +48,26 @@ public virtual string AzureWebsiteDefaultSubdomain
             }
         }
 
+        /// <summary>
+        /// Gets a value that uniquely identifies the site and slot.
+        /// </summary>
+        public virtual string AzureWebsiteUniqueSlotName
+        {
+            get
+            {
+                string name = GetSetting(EnvironmentSettingNames.AzureWebsiteName);
+                string slotName = GetSetting(EnvironmentSettingNames.AzureWebsiteSlotName);
+
+                if (!string.IsNullOrEmpty(slotName) &&
+                    !string.Equals(slotName, ScriptConstants.DefaultProductionSlotName, StringComparison.OrdinalIgnoreCase))
+                {
+                    name += $"-{slotName}";
+                }
+
+                return name?.ToLowerInvariant();
+            }
+        }
+
         public virtual void Reset()
         {
             _settingsCache.Clear();

src/WebJobs.Script/EnvironmentSettingNames.cs

@@ -9,6 +9,7 @@ public static class EnvironmentSettingNames
     {
         public const string AzureWebsiteName = "WEBSITE_SITE_NAME";
         public const string AzureWebsiteHostName = "WEBSITE_HOSTNAME";
+        public const string AzureWebsiteSlotName = "WEBSITE_SLOT_NAME";
         public const string AzureWebsiteOwnerName = "WEBSITE_OWNER_NAME";
         public const string AzureWebsiteInstanceId = "WEBSITE_INSTANCE_ID";
         public const string AzureWebsiteSku = "WEBSITE_SKU";

src/WebJobs.Script/Host/ScriptHost.cs

@@ -1090,11 +1090,11 @@ internal static string GetDefaultHostId(ScriptSettingsManager settingsManager, S
                     .Aggregate(new StringBuilder(), (b, c) => b.Append(c)).ToString();
                 hostId = $"{sanitizedMachineName}-{Math.Abs(scriptConfig.RootScriptPath.GetHashCode())}";
             }
-            else if (!string.IsNullOrEmpty(settingsManager.AzureWebsiteDefaultSubdomain))
+            else if (!string.IsNullOrEmpty(settingsManager.AzureWebsiteUniqueSlotName))
             {
-                // If running on Azure Web App, derive the host ID from the default subdomain
+                // If running on Azure Web App, derive the host ID from unique site slot name
                 // Trim any trailing - as they can cause problems with queue names
-                hostId = settingsManager.AzureWebsiteDefaultSubdomain.TrimEnd('-');
+                hostId = settingsManager.AzureWebsiteUniqueSlotName.TrimEnd('-');
             }
 
             if (!string.IsNullOrEmpty(hostId))

src/WebJobs.Script/ScriptConstants.cs

@@ -46,6 +46,7 @@ public static class ScriptConstants
         public const string AntaresLogIdHeaderName = "X-ARR-LOG-ID";
         public const string CheckLoadQueryParameterName = "checkLoad";
         public const string DynamicSku = "Dynamic";
+        public const string DefaultProductionSlotName = "production";
 
         public const string FeatureFlagDisableShadowCopy = "DisableShadowCopy";
 

test/WebJobs.Script.Tests/Diagnostics/SystemTraceWriterTests.cs

@@ -27,7 +27,7 @@ public SystemTraceWriterTests()
             _settingsManager.SetSetting(EnvironmentSettingNames.AzureWebsiteOwnerName, $"{_subscriptionId}+westuswebspace");
 
             _websiteName = "functionstest";
-            _settingsManager.SetSetting(EnvironmentSettingNames.AzureWebsiteHostName, $"{_websiteName}.azurewebsites.net");
+            _settingsManager.SetSetting(EnvironmentSettingNames.AzureWebsiteName, _websiteName);
 
             _mockEventGenerator = new Mock<IEventGenerator>(MockBehavior.Strict);
             _traceWriter = new SystemTraceWriter(_mockEventGenerator.Object, _settingsManager, TraceLevel.Verbose);
@@ -76,7 +76,7 @@ public void Trace_Error_EmitsExpectedEvent()
         public void Dispose()
         {
             _settingsManager.SetSetting(EnvironmentSettingNames.AzureWebsiteOwnerName, null);
-            _settingsManager.SetSetting(EnvironmentSettingNames.AzureWebsiteHostName, null);
+            _settingsManager.SetSetting(EnvironmentSettingNames.AzureWebsiteName, null);
         }
     }
 }

test/WebJobs.Script.Tests/ScriptHostTests.cs

@@ -1060,7 +1060,7 @@ public void GetDefaultHostId_AzureHost_ReturnsExpectedResult()
             var config = new ScriptHostConfiguration();
             string subdomain = "TEST-FUNCTIONS--";
             var scriptSettingsManagerMock = new Mock<ScriptSettingsManager>(MockBehavior.Strict);
-            scriptSettingsManagerMock.SetupGet(p => p.AzureWebsiteDefaultSubdomain).Returns(() => subdomain);
+            scriptSettingsManagerMock.SetupGet(p => p.AzureWebsiteUniqueSlotName).Returns(() => subdomain);
 
             string hostId = ScriptHost.GetDefaultHostId(scriptSettingsManagerMock.Object, config);
             Assert.Equal("test-functions", hostId);

test/WebJobs.Script.Tests/ScriptSettingsManagerTests.cs

@@ -0,0 +1,39 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Azure.WebJobs.Script.Config;
+using Xunit;
+
+namespace Microsoft.Azure.WebJobs.Script.Tests
+{
+    public class ScriptSettingsManagerTests
+    {
+        [Theory]
+        [InlineData("testsite", "production", "testsite")]
+        [InlineData("testsite", "Production", "testsite")]
+        [InlineData("testsite", null, "testsite")]
+        [InlineData("testsite", "staging", "testsite-staging")]
+        [InlineData("testsite", "dev", "testsite-dev")]
+        [InlineData("TestSite", "Dev", "testsite-dev")]
+        public void UniqueSlotName_ReturnsExpectedValue(string siteName, string slotName, string expectedValue)
+        {
+            var settingsManager = ScriptSettingsManager.Instance;
+
+            var variables = new Dictionary<string, string>
+            {
+                { EnvironmentSettingNames.AzureWebsiteName, siteName },
+                { EnvironmentSettingNames.AzureWebsiteSlotName, slotName },
+            };
+
+            using (var tempVariables = new TestScopedEnvironmentVariable(variables))
+            {
+                Assert.Equal(expectedValue, ScriptSettingsManager.Instance.AzureWebsiteUniqueSlotName);
+            }
+        }
+    }
+}

test/WebJobs.Script.Tests/WebJobs.Script.Tests.csproj

@@ -474,6 +474,7 @@
       <DependentUpon>Resources.resx</DependentUpon>
     </Compile>
     <Compile Include="ScriptHostTests.cs" />
+    <Compile Include="ScriptSettingsManagerTests.cs" />
     <Compile Include="Security\SecretsRepositoryTests.cs" />
     <Compile Include="Security\ScriptSecretSerializerTests.cs" />
     <Compile Include="Security\DataProtectionKeyValueConverterTests.cs" />