Adding nuget fallback folder config

Author: soninaren

src/WebJobs.Script.WebHost/WebJobsServiceCollectionExtensions.cs

@@ -93,7 +93,7 @@ public static IServiceProvider AddWebJobsScriptHost(this IServiceCollection serv
             builder.Register<IExtensionsManager>(c =>
             {
                 var hostInstance = c.Resolve<WebScriptHostManager>().Instance;
-                return new ExtensionsManager(hostInstance.ScriptConfig.RootScriptPath, hostInstance.Logger);
+                return new ExtensionsManager(hostInstance.ScriptConfig.RootScriptPath, hostInstance.Logger, hostInstance.ScriptConfig.NugetFallBackPath);
             });
 
             // The services below need to be scoped to a pseudo-tenant (warm/specialized environment)

src/WebJobs.Script/BindingExtensions/ExtensionsManager.cs

@@ -25,11 +25,13 @@ public class ExtensionsManager : IExtensionsManager
     {
         private readonly string _scriptRootPath;
         private readonly ILogger _logger;
+        private string _nugetFallbackPath;
 
-        public ExtensionsManager(string scriptRootPath, ILogger logger)
+        public ExtensionsManager(string scriptRootPath, ILogger logger, string nugetFallbackPath = null)
         {
             _scriptRootPath = scriptRootPath;
             _logger = logger;
+            _nugetFallbackPath = nugetFallbackPath;
         }
 
         internal string ProjectPath => Path.Combine(_scriptRootPath, ExtensionsProjectFileName);
@@ -130,6 +132,7 @@ internal virtual Task ProcessExtensionsProject(string projectFolder)
                 }
 
                 SetupProcessEnvironment(startInfo);
+                ApplyNugetFallbackFolderConfiguration(startInfo);
 
                 var process = new Process { StartInfo = startInfo };
                 process.ErrorDataReceived += (s, e) => logBuilder.Append(e.Data);
@@ -185,6 +188,30 @@ private void SetupProcessEnvironment(ProcessStartInfo startInfo)
             }
 
             startInfo.EnvironmentVariables.Add("DOTNET_SKIP_FIRST_TIME_EXPERIENCE", "true");
+            startInfo.EnvironmentVariables.Add(NugetXmlDocModeSettingName, NugetXmlDocSkipMode);
+        }
+
+        private void ApplyNugetFallbackFolderConfiguration(ProcessStartInfo startInfo)
+        {
+            string nugetFallbackFolderRootPath = Path.Combine(Environment.ExpandEnvironmentVariables("%programfiles(x86)%"), NugetFallbackFolderRootName);
+            if (string.IsNullOrEmpty(_nugetFallbackPath) && FileUtility.DirectoryExists(nugetFallbackFolderRootPath))
+            {
+                _nugetFallbackPath = FileUtility.EnumerateDirectories(nugetFallbackFolderRootPath)
+                    .Select(directoryPath =>
+                    {
+                        var directoryName = FileUtility.DirectoryInfoFromDirectoryName(directoryPath).Name;
+                        Version.TryParse(directoryName, out Version version);
+                        return new Tuple<string, Version>(directoryPath, version);
+                    })
+                    .Where(p => p.Item2 != null)
+                    .OrderByDescending(p => p.Item2)
+                    .FirstOrDefault().Item1?.ToString();
+            }
+
+            if (FileUtility.DirectoryExists(_nugetFallbackPath))
+            {
+                startInfo.Arguments += $" /p:RestoreFallbackFolders=\"{_nugetFallbackPath}\"";
+            }
         }
 
         private Exception CreateRestoreException(StringBuilder logBuilder, Exception innerException = null)

src/WebJobs.Script/Config/ScriptHostConfiguration.cs

@@ -34,6 +34,11 @@ public ScriptHostConfiguration()
         /// </summary>
         public string RootScriptPath { get; set; }
 
+        /// <summary>
+        /// Gets or sets NugetFallBackPath
+        /// </summary>
+        public string NugetFallBackPath { get; set; }
+
         /// <summary>
         /// Gets or sets the root path for log files.
         /// </summary>

src/WebJobs.Script/Host/ScriptHost.cs

@@ -1494,6 +1494,12 @@ internal static void ApplyConfiguration(JObject config, ScriptHostConfiguration
                 }
             }
 
+            JToken nugetFallbackFolder = config["nugetFallbackFolder"];
+            if (nugetFallbackFolder != null && nugetFallbackFolder.Type == JTokenType.String)
+            {
+                scriptConfig.NugetFallBackPath = (string)nugetFallbackFolder;
+            }
+
             // Apply Singleton configuration
             JObject configSection = (JObject)config["singleton"];
             JToken value = null;

src/WebJobs.Script/ScriptConstants.cs

@@ -82,6 +82,10 @@ public static class ScriptConstants
         public const string HttpMethodConstraintName = "httpMethod";
         public const string Snapshot = "snapshot";
         public const string Runtime = "runtime";
+        public const string NugetFallbackFolderRootName = "FuncNuGetFallback";
+        public const string NugetXmlDocModeSettingName = "NUGET_XMLDOC_MODE";
+        public const string NugetXmlDocSkipMode = "skip";
+
 
         public const int MaximumHostIdLength = 32;
         public const int DynamicSkuConnectionLimit = 50;