Single instance of worker configs (#3338)

* Fixing the worker config comparison so that it doesn't check against new instances

* update api signature

* update signature for languageworkeroptions

* update test

Author: mhoeger

src/WebJobs.Script/Rpc/Configuration/LanguageWorkerOptions.cs

@@ -7,6 +7,6 @@ namespace Microsoft.Azure.WebJobs.Script.Rpc
 {
     public class LanguageWorkerOptions
     {
-        public IEnumerable<WorkerConfig> WorkerConfigs { get; set; }
+        public IList<WorkerConfig> WorkerConfigs { get; set; }
     }
 }

src/WebJobs.Script/Rpc/Configuration/WorkerConfigFactory.cs

@@ -38,9 +38,11 @@ public WorkerConfigFactory(IConfiguration config, ILogger logger)
 
         public string WorkersDirPath { get; }
 
-        public IEnumerable<WorkerConfig> GetConfigs()
+        public IList<WorkerConfig> GetConfigs()
         {
             BuildWorkerProviderDictionary();
+            var result = new List<WorkerConfig>();
+
             foreach (var provider in WorkerProviders)
             {
                 var description = provider.GetDescription();
@@ -59,17 +61,20 @@ public IEnumerable<WorkerConfig> GetConfigs()
 
                 if (provider.TryConfigureArguments(arguments, _logger))
                 {
-                    yield return new WorkerConfig()
+                    var config = new WorkerConfig()
                     {
                         Description = description,
                         Arguments = arguments
                     };
+                    result.Add(config);
                 }
                 else
                 {
                     _logger.LogError($"Could not configure language worker {description.Language}.");
                 }
             }
+
+            return result;
         }
 
         internal void BuildWorkerProviderDictionary()

test/WebJobs.Script.Tests.Shared/TestHelpers.cs

@@ -239,7 +239,7 @@ public static async Task<string> ReadStreamToEnd(Stream stream)
             }
         }
 
-        public static IEnumerable<WorkerConfig> GetTestWorkerConfigs()
+        public static IList<WorkerConfig> GetTestWorkerConfigs()
         {
             var nodeWorkerDesc = GetTestWorkerDescription("node", ".js");
             var javaWorkerDesc = GetTestWorkerDescription("java", ".jar");