Adding internal filewatch logic to efficiently reload functions when changed

Author: mathewc

src/WebJobs.Script.Host/Program.cs

@@ -22,8 +22,14 @@ static void Main(string[] args)
                 RootPath = rootPath
             };
 
-            ScriptHost host = ScriptHost.Create(config);
-            host.RunAndBlock();
+            // Start the host and restart it if requested
+            ScriptHost host = null;
+            do
+            {
+                host = ScriptHost.Create(config);
+                host.RunAndBlock();
+            }
+            while (host.Restart);    
         }
     }
 }

src/WebJobs.Script/Binding/Binding.cs

@@ -14,9 +14,9 @@ namespace Microsoft.Azure.WebJobs.Script
 {
     internal abstract class Binding
     {
-        private readonly JobHostConfiguration _config;
+        private readonly ScriptHostConfiguration _config;
 
-        protected Binding(JobHostConfiguration config, string name, string type, FileAccess fileAccess, bool isTrigger)
+        protected Binding(ScriptHostConfiguration config, string name, string type, FileAccess fileAccess, bool isTrigger)
         {
             _config = config;
             Name = name;
@@ -37,7 +37,7 @@ protected Binding(JobHostConfiguration config, string name, string type, FileAcc
 
         public abstract Task BindAsync(IBinder binder, Stream stream, IReadOnlyDictionary<string, string> bindingData);
 
-        internal static Collection<Binding> GetBindings(JobHostConfiguration config, JArray bindingArray, FileAccess fileAccess)
+        internal static Collection<Binding> GetBindings(ScriptHostConfiguration config, JArray bindingArray, FileAccess fileAccess)
         {
             Collection<Binding> bindings = new Collection<Binding>();
 
@@ -103,12 +103,12 @@ internal static Collection<Binding> GetBindings(JobHostConfiguration config, JAr
 
         protected string Resolve(string name)
         {
-            if (_config.NameResolver == null)
+            if (_config.HostConfig.NameResolver == null)
             {
                 return name;
             }
 
-            return _config.NameResolver.ResolveWholeString(name);
+            return _config.HostConfig.NameResolver.ResolveWholeString(name);
         }
     }
 }

src/WebJobs.Script/Binding/BlobBinding.cs

@@ -13,7 +13,7 @@ internal class BlobBinding : Binding
     {
         private readonly BindingTemplate _pathBindingTemplate;
 
-        public BlobBinding(JobHostConfiguration config, string name, string path, FileAccess fileAccess, bool isTrigger) : base(config, name, "blob", fileAccess, isTrigger)
+        public BlobBinding(ScriptHostConfiguration config, string name, string path, FileAccess fileAccess, bool isTrigger) : base(config, name, "blob", fileAccess, isTrigger)
         {
             Path = path;
             _pathBindingTemplate = BindingTemplate.FromString(Path);

src/WebJobs.Script/Binding/QueueBinding.cs

@@ -13,7 +13,7 @@ internal class QueueBinding : Binding
     {
         private readonly BindingTemplate _queueNameBindingTemplate;
 
-        public QueueBinding(JobHostConfiguration config, string name, string queueName, FileAccess fileAccess, bool isTrigger) : base(config, name, "queue", fileAccess, isTrigger)
+        public QueueBinding(ScriptHostConfiguration config, string name, string queueName, FileAccess fileAccess, bool isTrigger) : base(config, name, "queue", fileAccess, isTrigger)
         {   
             QueueName = queueName;
             _queueNameBindingTemplate = BindingTemplate.FromString(QueueName);

src/WebJobs.Script/Binding/ServiceBusBinding.cs

@@ -13,7 +13,7 @@ internal class ServiceBusBinding : Binding
     {
         private readonly BindingTemplate _queueOrTopicNameBindingTemplate;
 
-        public ServiceBusBinding(JobHostConfiguration config, string name, string queueOrTopicName, FileAccess fileAccess, bool isTrigger) : base(config, name, "serviceBus", fileAccess, isTrigger)
+        public ServiceBusBinding(ScriptHostConfiguration config, string name, string queueOrTopicName, FileAccess fileAccess, bool isTrigger) : base(config, name, "serviceBus", fileAccess, isTrigger)
         {
             QueueOrTopicName = queueOrTopicName;
             _queueOrTopicNameBindingTemplate = BindingTemplate.FromString(QueueOrTopicName);

src/WebJobs.Script/Binding/TableBinding.cs

@@ -19,7 +19,7 @@ internal class TableBinding : Binding
         private readonly BindingTemplate _rowKeyBindingTemplate;
         private readonly TableQuery _tableQuery;
 
-        public TableBinding(JobHostConfiguration config, string name, string tableName, string partitionKey, string rowKey, FileAccess fileAccess, TableQuery tableQuery = null) : base(config, name, "queue", fileAccess, false)
+        public TableBinding(ScriptHostConfiguration config, string name, string tableName, string partitionKey, string rowKey, FileAccess fileAccess, TableQuery tableQuery = null) : base(config, name, "queue", fileAccess, false)
         {
             TableName = tableName;
             PartitionKey = partitionKey;

src/WebJobs.Script/Config/ScriptHost.cs

@@ -16,37 +16,37 @@ namespace Microsoft.Azure.WebJobs.Script
     public class ScriptHost : JobHost
     {
         private const string HostAssemblyName = "ScriptHost";
+        private FileSystemWatcher _fileWatcher;
 
-        protected ScriptHost(JobHostConfiguration config, ScriptHostConfiguration scriptConfig) 
-            : base(config)
+        protected ScriptHost(ScriptHostConfiguration scriptConfig) 
+            : base(scriptConfig.HostConfig)
         {
-            HostConfig = config;
             ScriptConfig = scriptConfig;
         }
 
-        public JobHostConfiguration HostConfig { get; private set; }
-
         public ScriptHostConfiguration ScriptConfig { get; private set; }
 
+        public bool Restart { get; private set; }
+
         protected virtual void Initialize()
         {
             List<FunctionDescriptorProvider> descriptionProviders = new List<FunctionDescriptorProvider>()
             {
-                new ScriptFunctionDescriptorProvider(HostConfig, ScriptConfig.RootPath),
-                new NodeFunctionDescriptorProvider(HostConfig, ScriptConfig.RootPath)
+                new ScriptFunctionDescriptorProvider(ScriptConfig),
+                new NodeFunctionDescriptorProvider(this, ScriptConfig)
             };
 
-            if (HostConfig.IsDevelopment)
+            if (ScriptConfig.HostConfig.IsDevelopment)
             {
-                HostConfig.UseDevelopmentSettings();
+                ScriptConfig.HostConfig.UseDevelopmentSettings();
             }
 
             // read host.json and apply to JobHostConfiguration
             string hostConfigFilePath = Path.Combine(ScriptConfig.RootPath, "host.json");
             Console.WriteLine(string.Format("Reading host configuration file '{0}'", hostConfigFilePath));
             string json = File.ReadAllText(hostConfigFilePath);
             JObject hostConfig = JObject.Parse(json);
-            ApplyConfiguration(hostConfig, HostConfig);
+            ApplyConfiguration(hostConfig, ScriptConfig);
 
             // read all script functions and apply to JobHostConfiguration
             Collection<FunctionDescriptor> functions = ReadFunctions(ScriptConfig, descriptionProviders);
@@ -57,8 +57,33 @@ protected virtual void Initialize()
             List<Type> types = new List<Type>();
             types.Add(type);
 
-            HostConfig.TypeLocator = new TypeLocator(types);
-            HostConfig.NameResolver = new NameResolver();
+            ScriptConfig.HostConfig.TypeLocator = new TypeLocator(types);
+            ScriptConfig.HostConfig.NameResolver = new NameResolver();
+
+            if (ScriptConfig.WatchFiles)
+            {
+                _fileWatcher = new FileSystemWatcher(ScriptConfig.RootPath, "*.json")
+                {
+                    IncludeSubdirectories = true,
+                    EnableRaisingEvents = true
+                };
+                _fileWatcher.Changed += OnConfigurationFileChanged;
+            }
+        }
+
+        private void StopAndRestart()
+        {
+            if (Restart)
+            {
+                // we've already received a restart call
+                return;
+            }
+
+            Console.WriteLine("The host configuration file has changed. Restarting.");
+
+            // Flag for restart and stop the host.
+            Restart = true;
+            Stop();
         }
 
         public static ScriptHost Create(ScriptHostConfiguration scriptConfig = null)
@@ -76,8 +101,7 @@ public static ScriptHost Create(ScriptHostConfiguration scriptConfig = null)
                 scriptConfig.RootPath = Path.Combine(Environment.CurrentDirectory, scriptConfig.RootPath);
             }
 
-            JobHostConfiguration config = new JobHostConfiguration();
-            ScriptHost scriptHost = new ScriptHost(config, scriptConfig);
+            ScriptHost scriptHost = new ScriptHost(scriptConfig);
             scriptHost.Initialize();
 
             return scriptHost;
@@ -180,14 +204,22 @@ internal static Collection<FunctionDescriptor> ReadFunctions(List<FunctionFolder
             return functionDescriptors;
         }
 
-        internal static void ApplyConfiguration(JObject config, JobHostConfiguration jobHostConfig)
+        internal static void ApplyConfiguration(JObject config, ScriptHostConfiguration scriptConfig)
         {
+            JobHostConfiguration hostConfig = scriptConfig.HostConfig;
+
             JToken hostId = (JToken)config["id"];
             if (hostId == null)
             {
                 throw new InvalidOperationException("An 'id' must be specified in the host configuration.");
             }
-            jobHostConfig.HostId = (string)hostId;
+            hostConfig.HostId = (string)hostId;
+
+            JToken watchFiles = (JToken)config["watchFiles"];
+            if (watchFiles != null && watchFiles.Type == JTokenType.Boolean)
+            {
+                scriptConfig.WatchFiles = (bool)watchFiles;
+            }
 
             // Apply Queues configuration
             JObject configSection = (JObject)config["queues"];
@@ -196,19 +228,19 @@ internal static void ApplyConfiguration(JObject config, JobHostConfiguration job
             {
                 if (configSection.TryGetValue("maxPollingInterval", out value))
                 {
-                    jobHostConfig.Queues.MaxPollingInterval = TimeSpan.FromMilliseconds((int)value);
+                    hostConfig.Queues.MaxPollingInterval = TimeSpan.FromMilliseconds((int)value);
                 }
                 if (configSection.TryGetValue("batchSize", out value))
                 {
-                    jobHostConfig.Queues.BatchSize = (int)value;
+                    hostConfig.Queues.BatchSize = (int)value;
                 }
                 if (configSection.TryGetValue("maxDequeueCount", out value))
                 {
-                    jobHostConfig.Queues.MaxDequeueCount = (int)value;
+                    hostConfig.Queues.MaxDequeueCount = (int)value;
                 }
                 if (configSection.TryGetValue("newBatchThreshold", out value))
                 {
-                    jobHostConfig.Queues.NewBatchThreshold = (int)value;
+                    hostConfig.Queues.NewBatchThreshold = (int)value;
                 }
             }
 
@@ -219,23 +251,23 @@ internal static void ApplyConfiguration(JObject config, JobHostConfiguration job
             {
                 if (configSection.TryGetValue("lockPeriod", out value))
                 {
-                    jobHostConfig.Singleton.LockPeriod = TimeSpan.Parse((string)value);
+                    hostConfig.Singleton.LockPeriod = TimeSpan.Parse((string)value);
                 }
                 if (configSection.TryGetValue("listenerLockPeriod", out value))
                 {
-                    jobHostConfig.Singleton.ListenerLockPeriod = TimeSpan.Parse((string)value);
+                    hostConfig.Singleton.ListenerLockPeriod = TimeSpan.Parse((string)value);
                 }
                 if (configSection.TryGetValue("listenerLockRecoveryPollingInterval", out value))
                 {
-                    jobHostConfig.Singleton.ListenerLockRecoveryPollingInterval = TimeSpan.Parse((string)value);
+                    hostConfig.Singleton.ListenerLockRecoveryPollingInterval = TimeSpan.Parse((string)value);
                 }
                 if (configSection.TryGetValue("lockAcquisitionTimeout", out value))
                 {
-                    jobHostConfig.Singleton.LockAcquisitionTimeout = TimeSpan.Parse((string)value);
+                    hostConfig.Singleton.LockAcquisitionTimeout = TimeSpan.Parse((string)value);
                 }
                 if (configSection.TryGetValue("lockAcquisitionPollingInterval", out value))
                 {
-                    jobHostConfig.Singleton.LockAcquisitionPollingInterval = TimeSpan.Parse((string)value);
+                    hostConfig.Singleton.LockAcquisitionPollingInterval = TimeSpan.Parse((string)value);
                 }
             }
 
@@ -250,7 +282,7 @@ internal static void ApplyConfiguration(JObject config, JobHostConfiguration job
                     sbConfig.MessageOptions.MaxConcurrentCalls = (int)value;
                 }
             }
-            jobHostConfig.UseServiceBus(sbConfig);
+            hostConfig.UseServiceBus(sbConfig);
 
             // Apply Tracing configuration
             configSection = (JObject)config["tracing"];
@@ -259,7 +291,7 @@ internal static void ApplyConfiguration(JObject config, JobHostConfiguration job
                 TraceLevel consoleLevel;
                 if (Enum.TryParse<TraceLevel>((string)value, true, out consoleLevel))
                 {
-                    jobHostConfig.Tracing.ConsoleLevel = consoleLevel;
+                    hostConfig.Tracing.ConsoleLevel = consoleLevel;
                 }
             }
 
@@ -270,9 +302,33 @@ internal static void ApplyConfiguration(JObject config, JobHostConfiguration job
             {
                 webHooksConfig = new WebHooksConfiguration((int)value);
             }
-            jobHostConfig.UseWebHooks(webHooksConfig);
+            hostConfig.UseWebHooks(webHooksConfig);
+
+            hostConfig.UseTimers();
+        }
+
+        private void OnConfigurationFileChanged(object sender, FileSystemEventArgs e)
+        {
+            string fileName = Path.GetFileName(e.Name);
+
+            if (!Restart &&
+                ((string.Compare(fileName, "host.json") == 0) || string.Compare(fileName, "function.json") == 0))
+            {
+                StopAndRestart();
+            }
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                if (_fileWatcher != null)
+                {
+                    _fileWatcher.Dispose();
+                }
+            }
 
-            jobHostConfig.UseTimers();
+            base.Dispose(disposing);
         }
     }
 }

src/WebJobs.Script/Config/ScriptHostConfiguration.cs

@@ -1,13 +1,34 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
+using System;
+
 namespace Microsoft.Azure.WebJobs.Script
 {
     public class ScriptHostConfiguration
     {
+        public ScriptHostConfiguration()
+        {
+            HostConfig = new JobHostConfiguration();
+            WatchFiles = true;
+        }
+
+        /// <summary>
+        /// Gets the <see cref="JobHostConfiguration"/>.
+        /// </summary>
+        public JobHostConfiguration HostConfig { get; private set; }
+
         /// <summary>
         /// Gets or sets the path to the script function directory.
         /// </summary>
         public string RootPath { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value dicating whether the <see cref="ScriptHost"/> should
+        /// monitor file for changes (default is true). When set to true, the host will
+        /// automatically react to source/config file changes. When set to false no file
+        /// monitoring will be performed.
+        /// </summary>
+        public bool WatchFiles { get; set; }
     }
 }

src/WebJobs.Script/Description/FunctionDescriptorProvider.cs

@@ -14,15 +14,24 @@ public abstract class FunctionDescriptorProvider
     {
         public abstract bool TryCreate(FunctionFolderInfo functionFolderInfo, out FunctionDescriptor functionDescriptor);
 
-        protected bool IsDisabled(string functionName, JObject trigger)
+        protected bool IsDisabled(string functionName, JObject value)
+        {
+            if (value != null && IsDisabled(value["disabled"]))
+            {
+                Console.WriteLine(string.Format("Function '{0}' is disabled", functionName));
+                return true;
+            }
+
+            return false;
+        }
+
+        private bool IsDisabled(JToken isDisabledValue)
         {
-            bool isDisabled = false;
-            JToken isDisabledValue = trigger["disabled"];
             if (isDisabledValue != null)
             {
                 if (isDisabledValue.Type == JTokenType.Boolean && (bool)isDisabledValue)
                 {
-                    isDisabled = true;
+                    return true;
                 }
                 else
                 {
@@ -32,17 +41,12 @@ protected bool IsDisabled(string functionName, JObject trigger)
                         (string.Compare(value, "1", StringComparison.OrdinalIgnoreCase) == 0 ||
                          string.Compare(value, "true", StringComparison.OrdinalIgnoreCase) == 0))
                     {
-                        isDisabled = true;
+                        return true;
                     }
                 }
             }
 
-            if (isDisabled)
-            {
-                Console.WriteLine(string.Format("Function '{0}' is disabled", functionName));
-            }
-
-            return isDisabled;
+            return false;
         }
 
         protected ParameterDescriptor ParseQueueTrigger(JObject trigger, Type triggerParameterType = null)