Implementing a resolver that resolves worker configurations from specified probing paths

src/WebJobs.Script.WebHost/WebHostServiceCollectionExtensions.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using System;
@@ -234,7 +234,18 @@ public static void AddWebJobsScriptHost(this IServiceCollection services, IConfi
             services.ConfigureOptionsWithChangeTokenSource<WorkerConfigurationResolverOptions, WorkerConfigurationResolverOptionsSetup, HostBuiltChangeTokenSource<WorkerConfigurationResolverOptions>>();
             services.ConfigureOptionsWithChangeTokenSource<LanguageWorkerOptions, LanguageWorkerOptionsSetup, HostBuiltChangeTokenSource<LanguageWorkerOptions>>();
 
-            services.AddSingleton<IWorkerConfigurationResolver, DefaultWorkerConfigurationResolver>();
+            services.AddSingleton<IWorkerConfigurationResolver>(p =>
+            {
+                var environment = p.GetService<IEnvironment>();
+                var workerConfigurationResolverOptions = p.GetService<IOptionsMonitor<WorkerConfigurationResolverOptions>>();
+                var workerProfileManager = p.GetService<IWorkerProfileManager>();
+                var loggerFactory = p.GetService<ILoggerFactory>();
+
+                return workerConfigurationResolverOptions.CurrentValue.IsDynamicWorkerResolutionEnabled ?
+                            new DynamicWorkerConfigurationResolver(loggerFactory, FileUtility.Instance, workerProfileManager, workerConfigurationResolverOptions) :
+                            new DefaultWorkerConfigurationResolver(loggerFactory, FileUtility.Instance, workerConfigurationResolverOptions);
+            });
+
             services.TryAddSingleton<IDependencyValidator, DependencyValidator>();
             services.TryAddSingleton<IJobHostMiddlewarePipeline>(s => DefaultMiddlewarePipeline.Empty);
 

src/WebJobs.Script/Config/FunctionsHostingConfigOptions.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using System;
@@ -91,6 +91,29 @@ internal string WorkerIndexingDisabledApps
             }
         }
 
+        /// <summary>
+        /// Gets a string delimited by '|' that contains the names of the language workers available through probing paths outside of the Host.
+        /// </summary>
+        internal string WorkersAvailableForDynamicResolution
+        {
+            get
+            {
+                return GetFeature(RpcWorkerConstants.WorkersAvailableForDynamicResolution) ?? string.Empty;
+            }
+        }
+
+        /// <summary>
+        /// Gets a string delimited by ';' that contains the versions of language workers to be ignored during probing outside of the Host.
+        /// Example value: "Worker1Name:Version1|Worker1Name:Version2|Worker2Name:Version1|Worker3Name:Version1".
+        /// </summary>
+        internal string IgnoredWorkersVersions
+        {
+            get
+            {
+                return GetFeature(RpcWorkerConstants.IgnoredWorkerVersions) ?? string.Empty;
+            }
+        }
+
         /// <summary>
         /// Gets a value indicating whether Linux Log Backoff is disabled in the hosting config.
         /// </summary>

src/WebJobs.Script/Environment/EnvironmentExtensions.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using System;
@@ -19,8 +19,6 @@ internal static class EnvironmentExtensions
     {
         private static bool? isApplicationInsightsAgentEnabled;
 
-        private static bool? isMultiLanguageEnabled;
-
         internal static string BaseDirectory { get; set; }
 
         public static string GetEnvironmentVariableOrDefault(this IEnvironment environment, string name, string defaultValue)
@@ -278,6 +276,16 @@ public static bool IsWindowsElasticPremium(this IEnvironment environment)
             return string.Equals(value, ScriptConstants.ElasticPremiumSku, StringComparison.OrdinalIgnoreCase);
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the application is running in a Windows App Service environment.
+        /// </summary>
+        /// <param name="environment">The environment to verify.</param>
+        /// <returns><see cref="true"/> if running in a Windows App Service app; otherwise, false.</returns>
+        public static bool IsHostedWindowsEnvironment(this IEnvironment environment)
+        {
+            return environment.IsWindowsAzureManagedHosting() || environment.IsWindowsConsumption() || environment.IsWindowsElasticPremium();
+        }
+
         public static bool IsDynamicSku(this IEnvironment environment)
         {
             return environment.IsConsumptionSku() || environment.IsWindowsElasticPremium();
@@ -467,11 +475,7 @@ public static bool IsLogicApp(this IEnvironment environment)
         /// </summary>
         public static bool IsMultiLanguageRuntimeEnvironment(this IEnvironment environment)
         {
-            if (!isMultiLanguageEnabled.HasValue)
-            {
-                isMultiLanguageEnabled = environment.IsLogicApp();
-            }
-            return isMultiLanguageEnabled.Value;
+            return environment.IsLogicApp();
         }
 
         /// <summary>
@@ -687,6 +691,11 @@ public static bool IsInProc(this IEnvironment environment, string workerRuntime
             return string.IsNullOrEmpty(workerRuntime) || string.Equals(workerRuntime, RpcWorkerConstants.DotNetLanguageWorkerName, StringComparison.OrdinalIgnoreCase);
         }
 
+        public static string GetPlatformReleaseChannel(this IEnvironment environment)
+        {
+            return environment.GetEnvironmentVariable(AntaresPlatformReleaseChannel) ?? ScriptConstants.LatestPlatformChannelNameUpper;
+        }
+
         public static bool IsApplicationInsightsAgentEnabled(this IEnvironment environment)
         {
             // cache the value of the environment variable
@@ -709,7 +718,6 @@ public static bool IsApplicationInsightsAgentEnabled(this IEnvironment environme
         /// </summary>
         public static void ClearCache()
         {
-            isMultiLanguageEnabled = null;
             isApplicationInsightsAgentEnabled = null;
         }
 

src/WebJobs.Script/Environment/EnvironmentSettingNames.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 namespace Microsoft.Azure.WebJobs.Script
@@ -35,6 +35,7 @@ public static class EnvironmentSettingNames
         public const string AppInsightsAgent = "APPLICATIONINSIGHTS_ENABLE_AGENT";
         public const string FunctionsExtensionVersion = "FUNCTIONS_EXTENSION_VERSION";
         public const string FunctionWorkerRuntime = "FUNCTIONS_WORKER_RUNTIME";
+        public const string WorkerProbingPaths = "WORKER_PROBING_PATHS";
         public const string ContainerName = "CONTAINER_NAME";
         public const string WebsitePodName = "WEBSITE_POD_NAME";
         public const string LegionServiceHost = "LEGION_SERVICE_HOST";

src/WebJobs.Script/ScriptConstants.cs

@@ -1,7 +1,8 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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.Collections.Immutable;
 using NuGet.Versioning;
 
@@ -133,6 +134,7 @@ public static class ScriptConstants
         public const string FeatureFlagDisableWebHostLogForwarding = "DisableWebHostLogForwarding";
         public const string FeatureFlagDisableMergedWebHostScriptHostConfiguration = "DisableMergedConfiguration";
         public const string FeatureFlagEnableWorkerIndexing = "EnableWorkerIndexing";
+        public const string FeatureFlagDisableDynamicWorkerResolution = "DisableDynamicWorkerResolution";
         public const string FeatureFlagEnableDebugTracing = "EnableDebugTracing";
         public const string FeatureFlagEnableProxies = "EnableProxies";
         public const string FeatureFlagStrictHISModeEnabled = "StrictHISModeEnabled";
@@ -248,6 +250,7 @@ public static class ScriptConstants
         public static readonly long DefaultMaxRequestBodySize = 104857600;
 
         public static readonly ImmutableArray<string> SystemLogCategoryPrefixes = ImmutableArray.Create("Microsoft.Azure.WebJobs.", "Function.", "Worker.", "Host.");
+        public static readonly HashSet<string> HostCapabilities = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
 
         public static readonly string FunctionMetadataDirectTypeKey = "DirectType";
         public static readonly string LiveLogsSessionAIKey = "#AzFuncLiveLogsSessionId";

src/WebJobs.Script/Workers/Rpc/Configuration/DefaultWorkerConfigurationResolver.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using System;
@@ -44,7 +44,7 @@ public WorkerConfigurationInfo GetConfigurationInfo()
                 }
             }
 
-            return new WorkerConfigurationInfo(_workerConfigurationResolverOptions.CurrentValue.WorkersRootDirPath, workerConfigPaths);
+            return new WorkerConfigurationInfo(_workerConfigurationResolverOptions.CurrentValue.WorkersRootDirPath, workerConfigPaths, _workerConfigurationResolverOptions.CurrentValue.LanguageWorkersSettings);
         }
     }
 }