Refactor RuntimeConfig into Interface with Local and Hosted Providers

src/Cli/ConfigGenerator.cs

@@ -1104,7 +1104,7 @@ public static bool IsConfigValid(ValidateOptions options, FileSystemRuntimeConfi
                 _logger.LogInformation("Loaded config file: {runtimeConfigFile}", runtimeConfigFile);
             }
 
-            RuntimeConfigProvider runtimeConfigProvider = new(loader);
+            LocalRuntimeConfigProvider runtimeConfigProvider = new(loader);
 
             ILogger<RuntimeConfigValidator> runtimeConfigValidatorLogger = LoggerFactoryForCli.CreateLogger<RuntimeConfigValidator>();
             RuntimeConfigValidator runtimeConfigValidator = new(runtimeConfigProvider, fileSystem, runtimeConfigValidatorLogger, true);

src/Core/Configurations/ConfigFileWatcher.cs → src/Config/ConfigFileWatcher.cs

@@ -1,22 +1,29 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-namespace Azure.DataApiBuilder.Core.Configurations;
+using Azure.DataApiBuilder.Config.ObjectModel;
 
+namespace Azure.DataApiBuilder.Config;
+
+/// <summary>
+/// This class is responsible for monitoring the config file from the
+/// local file system, and if changes are detected, triggering the
+/// required logic to begin a hot reload scenario.
+/// </summary>
 public class ConfigFileWatcher
 {
     private FileSystemWatcher? _fileWatcher;
-    private readonly RuntimeConfigProvider? _configProvider;
+    private FileSystemRuntimeConfigLoader _configLoader;
 
-    public ConfigFileWatcher(RuntimeConfigProvider configProvider, string directoryName, string configFileName)
+    public ConfigFileWatcher(FileSystemRuntimeConfigLoader configLoader, string directoryName, string configFileName)
     {
         _fileWatcher = new FileSystemWatcher(directoryName)
         {
             Filter = configFileName,
             EnableRaisingEvents = true
         };
 
-        _configProvider = configProvider;
+        _configLoader = configLoader;
         _fileWatcher.Changed += OnConfigFileChange;
     }
 
@@ -31,14 +38,19 @@ private void OnConfigFileChange(object sender, FileSystemEventArgs e)
     {
         try
         {
-            if (_configProvider is null)
+            if (_configLoader is null)
+            {
+                throw new ArgumentNullException("ConfigLoader can not be null.");
+            }
+
+            if (_configLoader.RuntimeConfig is null)
             {
-                throw new ArgumentNullException("_configProvider can not be null.");
+                throw new ArgumentNullException("RuntimeConfig can not be null.");
             }
 
-            if (!_configProvider.IsLateConfigured && _configProvider.GetConfig().IsDevelopmentMode())
+            if (_configLoader.RuntimeConfig.IsDevelopmentMode())
             {
-                _configProvider.HotReloadConfig();
+                _configLoader.HotReloadConfig(_configLoader.RuntimeConfig.DefaultDataSourceName);
             }
         }
         catch (Exception ex)

src/Config/FileSystemRuntimeConfigLoader.cs

@@ -8,6 +8,7 @@
 using System.Text.Json;
 using Azure.DataApiBuilder.Config.ObjectModel;
 using Azure.DataApiBuilder.Service.Exceptions;
+using Microsoft.Extensions.Logging;
 
 namespace Azure.DataApiBuilder.Config;
 
@@ -29,6 +30,8 @@ public class FileSystemRuntimeConfigLoader : RuntimeConfigLoader
     // or user provided config file which could be a relative file path, absolute file path or simply the file name assumed to be in current directory.
     private string _baseConfigFilePath;
 
+    private ConfigFileWatcher? _configFileWatcher;
+
     private readonly IFileSystem _fileSystem;
 
     public const string CONFIGFILE_NAME = "dab-config";
@@ -87,32 +90,78 @@ public string GetConfigFileName()
         return configFileName;
     }
 
+    /// <summary>
+    /// Checks if we have already attempted to configure the file watcher, if not
+    /// instantiate the file watcher if we are in the development mode.
+    /// Returns true if we instantiate a new file watcher.
+    /// </summary>
+    private bool TrySetupConfigFileWatcher()
+    {
+        if (_configFileWatcher is not null)
+        {
+            return false;
+        }
+
+        if (RuntimeConfig is not null && RuntimeConfig.IsDevelopmentMode())
+        {
+            try
+            {
+                _configFileWatcher = new(this, GetConfigDirectoryName(), GetConfigFileName());
+            }
+            catch (Exception ex)
+            {
+                // Need to remove the dependencies in startup on the RuntimeConfigProvider
+                // before we can have an ILogger here.
+                Console.WriteLine($"Attempt to configure config file watcher for hot reload failed due to: {ex.Message}.");
+            }
+
+            return _configFileWatcher is not null;
+        }
+
+        return false;
+    }
+
     /// <summary>
     /// Load the runtime config from the specified path.
     /// </summary>
     /// <param name="path">The path to the dab-config.json file.</param>
     /// <param name="config">The loaded <c>RuntimeConfig</c>, or null if none was loaded.</param>
     /// <param name="replaceEnvVar">Whether to replace environment variable with its
     /// value or not while deserializing.</param>
+    /// <param name="logger">ILogger for logging errors.</param>
     /// <returns>True if the config was loaded, otherwise false.</returns>
     public bool TryLoadConfig(
         string path,
         [NotNullWhen(true)] out RuntimeConfig? config,
-        bool replaceEnvVar = false)
+        bool replaceEnvVar = false,
+        ILogger? logger = null,
+        string? defaultDataSourceName = null)
     {
         if (_fileSystem.File.Exists(path))
         {
             Console.WriteLine($"Loading config file from {path}.");
             string json = _fileSystem.File.ReadAllText(path);
-            return TryParseConfig(json, out config, connectionString: _connectionString, replaceEnvVar: replaceEnvVar);
+            bool configParsed = TryParseConfig(json, out RuntimeConfig, connectionString: _connectionString, replaceEnvVar: replaceEnvVar);
+            TrySetupConfigFileWatcher();
+            config = RuntimeConfig;
+            if (RuntimeConfig is not null && defaultDataSourceName is not null)
+            {
+                RuntimeConfig.DefaultDataSourceName = defaultDataSourceName;
+            }
+
+            return configParsed;
+        }
+
+        string errorMessage = $"Unable to find config file: {path} does not exist.";
+        if (logger is null)
+        {
+            Console.Error.WriteLine(errorMessage);
         }
         else
         {
-            // Unable to use ILogger because this code is invoked before LoggerFactory
-            // is instantiated.
-            Console.WriteLine($"Unable to find config file: {path} does not exist.");
+            logger.LogError(message: errorMessage);
         }
-
+        
         config = null;
         return false;
     }
@@ -124,11 +173,20 @@ public string GetConfigFileName()
     /// <param name="replaceEnvVar">Whether to replace environment variable with its
     /// value or not while deserializing.</param>
     /// <returns>True if the config was loaded, otherwise false.</returns>
-    public override bool TryLoadKnownConfig([NotNullWhen(true)] out RuntimeConfig? config, bool replaceEnvVar = false)
+    public override bool TryLoadKnownConfig([NotNullWhen(true)] out RuntimeConfig? config, bool replaceEnvVar = false, string? defaultDataSourceName = null)
     {
         return TryLoadConfig(ConfigFilePath, out config, replaceEnvVar);
     }
 
+    /// <summary>
+    /// Hot Reloads the runtime config when the file watcher
+    /// is active and detects a change to the underlying config file.
+    /// </summary>
+    public void HotReloadConfig(string defaultDataSourceName)
+    {
+        TryLoadKnownConfig(out _, replaceEnvVar: true, defaultDataSourceName);
+    }
+
     /// <summary>
     /// Precedence of environments is
     /// 1) Value of DAB_ENVIRONMENT.

src/Config/ObjectModel/RuntimeConfig.cs

@@ -130,7 +130,7 @@ public bool AllowIntrospection
         }
     }
 
-    private string _defaultDataSourceName;
+    public string DefaultDataSourceName;
 
     private Dictionary<string, DataSource> _dataSourceNameToDataSource;
 
@@ -169,18 +169,18 @@ public RuntimeConfig(string? Schema, DataSource DataSource, RuntimeEntities Enti
         this.DataSource = DataSource;
         this.Runtime = Runtime;
         this.Entities = Entities;
-        _defaultDataSourceName = Guid.NewGuid().ToString();
+        DefaultDataSourceName = Guid.NewGuid().ToString(); //DataSource.ConnectionString.GetHashCode().ToString();
 
         // we will set them up with default values
         _dataSourceNameToDataSource = new Dictionary<string, DataSource>
         {
-            { _defaultDataSourceName, this.DataSource }
+            { DefaultDataSourceName, this.DataSource }
         };
 
         _entityNameToDataSourceName = new Dictionary<string, string>();
         foreach (KeyValuePair<string, Entity> entity in Entities)
         {
-            _entityNameToDataSourceName.TryAdd(entity.Key, _defaultDataSourceName);
+            _entityNameToDataSourceName.TryAdd(entity.Key, DefaultDataSourceName);
         }
 
         // Process data source and entities information for each database in multiple database scenario.
@@ -241,7 +241,7 @@ public RuntimeConfig(string Schema, DataSource DataSource, RuntimeOptions Runtim
         this.DataSource = DataSource;
         this.Runtime = Runtime;
         this.Entities = Entities;
-        _defaultDataSourceName = DefaultDataSourceName;
+        DefaultDataSourceName = DefaultDataSourceName;
         _dataSourceNameToDataSource = DataSourceNameToDataSource;
         _entityNameToDataSourceName = EntityNameToDataSourceName;
         this.DataSourceFiles = DataSourceFiles;
@@ -311,7 +311,7 @@ public bool CheckDataSourceExists(string dataSourceName)
     public string GetDefaultDataSourceName()
 #pragma warning restore CA1024 // Use properties where appropriate
     {
-        return _defaultDataSourceName;
+        return DefaultDataSourceName;
     }
 
     /// <summary>

src/Config/RuntimeConfigLoader.cs

@@ -22,6 +22,8 @@ public abstract class RuntimeConfigLoader
 {
     protected readonly string? _connectionString;
 
+    public RuntimeConfig? RuntimeConfig { get; set; }
+
     public RuntimeConfigLoader(string? connectionString = null)
     {
         _connectionString = connectionString;
@@ -34,7 +36,7 @@ public RuntimeConfigLoader(string? connectionString = null)
     /// <param name="replaceEnvVar">Whether to replace environment variable with its
     /// value or not while deserializing.</param>
     /// <returns>True if the config was loaded, otherwise false.</returns>
-    public abstract bool TryLoadKnownConfig([NotNullWhen(true)] out RuntimeConfig? config, bool replaceEnvVar = false);
+    public abstract bool TryLoadKnownConfig([NotNullWhen(true)] out RuntimeConfig? config, bool replaceEnvVar = false, string? defaultDataSourceName = null);
 
     /// <summary>
     /// Returns the link to the published draft schema.
@@ -54,6 +56,7 @@ public RuntimeConfigLoader(string? connectionString = null)
     /// value or not while deserializing. By default, no replacement happens.</param>
     /// <param name="dataSourceName"> datasource name for which to add connection string</param>
     /// <param name="datasourceNameToConnectionString"> dictionary of datasource name to connection string</param>
+    /// <param name="replacementFailureMode">Determines failure mode for env variable replacement.</param>
     public static bool TryParseConfig(string json,
         [NotNullWhen(true)] out RuntimeConfig? config,
         ILogger? logger = null,

src/Core/AuthenticationHelpers/AuthenticationSimulator/SimulatorAuthenticationHandler.cs

@@ -32,7 +32,7 @@ public class SimulatorAuthenticationHandler : AuthenticationHandler<Authenticati
     /// <param name="encoder">URL encoder.</param>
     /// <param name="clock">System clock.</param>
     public SimulatorAuthenticationHandler(
-        RuntimeConfigProvider runtimeConfigProvider,
+        IRuntimeConfigProvider runtimeConfigProvider,
         IOptionsMonitor<AuthenticationSchemeOptions> options,
         ILoggerFactory logger,
         UrlEncoder encoder,

src/Core/AuthenticationHelpers/ClientRoleHeaderAuthenticationMiddleware.cs

@@ -34,7 +34,7 @@ public class ClientRoleHeaderAuthenticationMiddleware
 
     public ClientRoleHeaderAuthenticationMiddleware(RequestDelegate next,
         ILogger<ClientRoleHeaderAuthenticationMiddleware> logger,
-        RuntimeConfigProvider runtimeConfigProvider)
+        IRuntimeConfigProvider runtimeConfigProvider)
     {
         _nextMiddleware = next;
         _logger = logger;

src/Core/Authorization/AuthorizationResolver.cs

@@ -23,7 +23,7 @@ namespace Azure.DataApiBuilder.Core.Authorization;
 /// </summary>
 public class AuthorizationResolver : IAuthorizationResolver
 {
-    private readonly RuntimeConfigProvider _runtimeConfigProvider;
+    private readonly IRuntimeConfigProvider _runtimeConfigProvider;
     private readonly IMetadataProviderFactory _metadataProviderFactory;
     public const string WILDCARD = "*";
     public const string CLAIM_PREFIX = "@claims.";
@@ -36,7 +36,7 @@ public class AuthorizationResolver : IAuthorizationResolver
     public Dictionary<string, EntityMetadata> EntityPermissionsMap { get; private set; } = new();
 
     public AuthorizationResolver(
-        RuntimeConfigProvider runtimeConfigProvider,
+        IRuntimeConfigProvider runtimeConfigProvider,
         IMetadataProviderFactory metadataProviderFactory
         )
     {
@@ -48,7 +48,7 @@ IMetadataProviderFactory metadataProviderFactory
         }
         else
         {
-            runtimeConfigProvider.RuntimeConfigLoadedHandlers.Add((RuntimeConfigProvider sender, RuntimeConfig config) =>
+            runtimeConfigProvider.RuntimeConfigLoadedHandlers.Add((IRuntimeConfigProvider sender, RuntimeConfig config) =>
             {
                 SetEntityPermissionMap(config);
                 return Task.FromResult(true);