Fixing bugs for sticky slot app settings

Directory.Packages.props

@@ -39,7 +39,7 @@
     <PackageVersion Include="Azure.Provisioning" Version="1.4.0" />
     <PackageVersion Include="Azure.Provisioning.AppConfiguration" Version="1.1.0" />
     <PackageVersion Include="Azure.Provisioning.AppContainers" Version="1.1.0" />
-    <PackageVersion Include="Azure.Provisioning.AppService" Version="1.3.0" />
+    <PackageVersion Include="Azure.Provisioning.AppService" Version="1.3.1" />
     <PackageVersion Include="Azure.Provisioning.ApplicationInsights" Version="1.1.0" />
     <PackageVersion Include="Azure.Provisioning.ContainerRegistry" Version="1.1.0" />
     <PackageVersion Include="Azure.Provisioning.CognitiveServices" Version="1.1.0" />

src/Aspire.Hosting.Azure.AppService/AzureAppServiceWebSiteResource.cs

@@ -239,18 +239,30 @@ private async Task<string> GetAppServiceWebsiteNameAsync(PipelineStepContext con
         var websiteSuffix = await computerEnv.WebSiteSuffix.GetValueAsync(context.CancellationToken).ConfigureAwait(false);
         var websiteName = $"{TargetResource.Name.ToLowerInvariant()}-{websiteSuffix}";
 
-        if (!string.IsNullOrWhiteSpace(deploymentSlot))
+        if (string.IsNullOrWhiteSpace(deploymentSlot))
         {
-            websiteName += $"-{deploymentSlot}";
+            return TruncateToMaxLength(websiteName, 60);
         }
 
-        if (websiteName.Length > 60)
+        websiteName = TruncateToMaxLength(websiteName, MaxWebSiteNamePrefixLengthWithSlot);
+        websiteName += $"-{deploymentSlot}";
+
+        return TruncateToMaxLength(websiteName, MaxHostPrefixLengthWithSlot);
+    }
+
+    private static string TruncateToMaxLength(string value, int maxLength)
+    {
+        if (value.Length <= maxLength)
         {
-            websiteName = websiteName.Substring(0, 60);
+            return value;
         }
-        return websiteName;
+        return value.Substring(0, maxLength);
     }
 
     private const string AzureManagementScope = "https://management.azure.com/.default";
     private const string AzureManagementEndpoint = "https://management.azure.com/";
+    // For Azure App Service, the maximum length for a host name is 63 characters. With slot, the host name is 59 characters, with 4 characters reserved for random slot suffix (very edge case).
+    // Source of truth: https://msazure.visualstudio.com/One/_git/AAPT-Antares-Websites?path=%2Fsrc%2FHosting%2FAdministrationService%2FMicrosoft.Web.Hosting.Administration.Api%2FCommonConstants.cs&_a=contents&version=GBdev
+    internal const int MaxHostPrefixLengthWithSlot = 59;
+    internal const int MaxWebSiteNamePrefixLengthWithSlot = 40;
 }

src/Aspire.Hosting.Azure.AppService/AzureAppServiceWebsiteContext.cs

@@ -46,8 +46,11 @@ record struct EndpointMapping(string Scheme, BicepValue<string> Host, int Port,
     /// <returns>A <see cref="BicepValue{T}"/> representing the slot hostname, truncated to 60 characters.</returns>
     public BicepValue<string> GetSlotHostName(BicepValue<string> deploymentSlot)
     {
+        var websitePrefix = BicepFunction.Take(
+            BicepFunction.Interpolate($"{BicepFunction.ToLower(resource.Name)}-{AzureAppServiceEnvironmentResource.GetWebSiteSuffixBicep()}"), AzureAppServiceWebSiteResource.MaxWebSiteNamePrefixLengthWithSlot);
+
         return BicepFunction.Take(
-        BicepFunction.Interpolate($"{BicepFunction.ToLower(resource.Name)}-{AzureAppServiceEnvironmentResource.GetWebSiteSuffixBicep()}-{BicepFunction.ToLower(deploymentSlot)}"), 60);
+            BicepFunction.Interpolate($"{websitePrefix}-{BicepFunction.ToLower(deploymentSlot)}"), AzureAppServiceWebSiteResource.MaxHostPrefixLengthWithSlot);
     }
 
     public async Task ProcessAsync(CancellationToken cancellationToken)
@@ -284,6 +287,7 @@ public void BuildWebSite(AzureResourceInfrastructure infra)
     /// <param name="acrMidParameter">The Azure Container Registry managed identity parameter.</param>
     /// <param name="acrClientIdParameter">The Azure Container Registry client ID parameter.</param>
     /// <param name="containerImage">The container image parameter.</param>
+    /// <param name="slotConfigNames">The slot configuration names resource.</param>
     /// <param name="isSlot">Indicates whether this is a deployment slot.</param>
     /// <param name="parentWebSite">The parent website when creating a slot.</param>
     /// <param name="deploymentSlot">The deployment slot name.</param>
@@ -295,6 +299,7 @@ private object CreateAndConfigureWebSite(
     BicepValue<string> acrMidParameter,
     ProvisioningParameter acrClientIdParameter,
     ProvisioningParameter containerImage,
+    HashSet<string> slotConfigNames,
     bool isSlot = false,
     WebSite? parentWebSite = null,
     BicepValue<string>? deploymentSlot = null)
@@ -423,6 +428,12 @@ private object CreateAndConfigureWebSite(
             {
                 slot.SiteConfig.AppSettings.Add(new AppServiceNameValuePair { Name = kv.Key, Value = value });
             }
+
+            // make app service references as sticky settings for slots
+            if (kv.Value is EndpointReference)
+            {
+                slotConfigNames.Add(kv.Key);
+            }
         }
 
         if (Args.Count > 0)
@@ -559,6 +570,9 @@ static FunctionCallExpression Join(BicepExpression args, string delimeter) =>
         if (environmentContext.Environment.EnableDashboard)
         {
             webSiteRa = AddDashboardPermissionAndSettings(webSite, acrClientIdParameter, deploymentSlot);
+
+            // Make OTEL_SERVICE_NAME a deployment slot sticky appsetting if dashboard is enabled
+            slotConfigNames.Add("OTEL_SERVICE_NAME");
         }
 
         if (webSite is WebSite webSiteObject)
@@ -602,6 +616,7 @@ private void BuildWebSiteCore(
 
         // Create parent WebSite from existing
         WebSite? parentWebSite = null;
+        HashSet<string> stickyConfigNames = new();
 
         if (deploymentSlot is not null)
         {
@@ -617,6 +632,7 @@ private void BuildWebSiteCore(
             acrMidParameter,
             acrClientIdParameter,
             containerImage,
+            stickyConfigNames,
             isSlot: deploymentSlot is not null,
             parentWebSite: parentWebSite,
             deploymentSlot: deploymentSlot);
@@ -644,6 +660,8 @@ private void BuildWebSiteCore(
                 }
             }
         }
+
+        AddStickySlotSettings(deploymentSlot is null ? (WebSite)webSite : parentWebSite, stickyConfigNames);
     }
 
     /// <summary>
@@ -662,6 +680,7 @@ private void BuildWebSiteAndSlot(
         var acrMidParameter = environmentContext.Environment.ContainerRegistryManagedIdentityId.AsProvisioningParameter(infra);
         var acrClientIdParameter = environmentContext.Environment.ContainerRegistryClientId.AsProvisioningParameter(infra);
         var containerImage = AllocateParameter(new ContainerImageReference(Resource));
+        HashSet<string> stickyConfigNames = new();
 
         // Main site
         var webSite = (WebSite)CreateAndConfigureWebSite(
@@ -671,6 +690,7 @@ private void BuildWebSiteAndSlot(
             acrMidParameter,
             acrClientIdParameter,
             containerImage,
+            stickyConfigNames,
             isSlot: false);
 
         // Slot
@@ -681,6 +701,7 @@ private void BuildWebSiteAndSlot(
             acrMidParameter,
             acrClientIdParameter,
             containerImage,
+            stickyConfigNames,
             isSlot: true,
             parentWebSite: (WebSite)webSite,
             deploymentSlot: deploymentSlot);
@@ -702,6 +723,8 @@ private void BuildWebSiteAndSlot(
                 customizeWebSiteSlotAnnotation.Configure(infra, webSiteSlot);
             }
         }
+
+        AddStickySlotSettings(webSite, stickyConfigNames);
     }
 
     private BicepValue<string> GetEndpointValue(EndpointMapping mapping, EndpointProperty property)
@@ -856,6 +879,31 @@ private void UpdateHostNameForSlot(BicepValue<string> slotName)
         }
     }
 
+    /// <summary>
+    /// Configures sticky slot settings to ensure deployment slot specific app settings remains with each slot during swaps.
+    /// </summary>
+    /// <param name="parentWebSite">The parent WebSite resource.</param>
+    /// <param name="stickyConfigNames">The set of deployment slot app settings</param>
+    private void AddStickySlotSettings(WebSite? parentWebSite, HashSet<string> stickyConfigNames)
+    {
+        if (stickyConfigNames.Count == 0)
+        {
+            return;
+        }
+
+        SlotConfigNames slotConfigNames = new("slotConfigNames")
+        {
+            Parent = parentWebSite
+        };
+
+        foreach (var stickyConfig in stickyConfigNames)
+        {
+            slotConfigNames.AppSettingNames.Add(stickyConfig);
+        }
+
+        Infra.Add(slotConfigNames);
+    }
+
     enum SecretType
     {
         None,

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceContainerWithoutTargetPortUsesDefaultPort.verified.bicep

@@ -92,3 +92,13 @@ resource container1_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceProjectWithApplicationInsightsSetsAppSettings.verified.bicep

@@ -122,3 +122,13 @@ resource project1_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceProjectWithoutTargetPortUsesContainerPort.verified.bicep

@@ -106,3 +106,13 @@ resource project1_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceToEnvironmentWithoutDashboard.verified.bicep

@@ -74,3 +74,14 @@ resource webapp 'Microsoft.Web/sites@2025-03-01' = {
     }
   }
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'PROJECT1_HTTP'
+      'services__project1__http__0'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceWithArgs.verified.bicep

@@ -118,3 +118,15 @@ resource project2_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'PROJECT1_HTTP'
+      'services__project1__http__0'
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceWithDeploymentSlot.verified.bicep

@@ -111,3 +111,13 @@ resource project1_website_slot_ra 'Microsoft.Authorization/roleAssignments@2022-
   }
   scope: webappslot
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceWithDeploymentSlotParameter.verified.bicep

@@ -113,3 +113,13 @@ resource project1_website_slot_ra 'Microsoft.Authorization/roleAssignments@2022-
   }
   scope: webappslot
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceWithTargetPort.verified.bicep

@@ -120,3 +120,17 @@ resource project2_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'PROJECT1_HTTPS'
+      'services__project1__https__0'
+      'PROJECT1_HTTP'
+      'services__project1__http__0'
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddAppServiceWithTargetPortMultipleEndpoints.verified.bicep

@@ -108,3 +108,13 @@ resource project2_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddContainerAppEnvironmentAddsDeploymentTargetWithContainerAppToProjectResources.verified.bicep

@@ -107,3 +107,13 @@ resource api_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01' = {
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AddDockerfileWithAppServiceInfrastructureAddsDeploymentTargetWithAppServiceToContainerResources.verified.bicep

@@ -96,3 +96,13 @@ resource api_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01' = {
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.AzureAppServiceSupportBaitAndSwitchResources.verified.bicep

@@ -104,3 +104,13 @@ resource api_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01' = {
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.EndpointReferencesAreResolvedAcrossProjects.verified.bicep

@@ -114,3 +114,15 @@ resource project2_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'PROJECT1_HTTP'
+      'services__project1__http__0'
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}

tests/Aspire.Hosting.Azure.Tests/Snapshots/AzureAppServiceTests.KeyvaultReferenceHandling.verified.bicep

@@ -164,3 +164,13 @@ resource api_website_ra 'Microsoft.Authorization/roleAssignments@2022-04-01' = {
   }
   scope: webapp
 }
+
+resource slotConfigNames 'Microsoft.Web/sites/config@2025-03-01' = {
+  name: 'slotConfigNames'
+  properties: {
+    appSettingNames: [
+      'OTEL_SERVICE_NAME'
+    ]
+  }
+  parent: webapp
+}