[Cherry pick] Remove redundant logging of found config file (#1670)

Cherry picking #1669 

Original description:

## Why make this change?
- With the overhaul of config system PR #1402 , we started seeing
redundant logs about which config file is being used.

## What is this change?

- Store the environment based config file name found at construction
time in the property `ConfigFileName`.
- Remove Console writeline statements while checking for existence of
file since this leads to multiple logs - one from CLI before starting
the engine and second from within the engine itself when calling
TryPargeConfig
- Add a single log of the loaded file in CLI

## How was this tested?
- Manually, using the `start` command of CLI as well as triggering the
engine directly with argument: `--ConfigFileName`

1. Starting with default config:
**Before**:

![image](https://github.com/Azure/data-api-builder/assets/3513779/a29d4aff-19db-49c7-a745-b6bbdb5c62cc)

**After**:

![image](https://github.com/Azure/data-api-builder/assets/3513779/62f65222-de59-4525-b0b1-ead407d43b4e)

2. Starting with user provided config:
**Before**:

![image](https://github.com/Azure/data-api-builder/assets/3513779/b762c873-ade6-47bb-b094-44960176d90f)

**After**:

![image](https://github.com/Azure/data-api-builder/assets/3513779/2f977a72-bfdf-43fb-9cc9-806ea717b546)

3. Trying to start with missing file name - same behvior as before

![image](https://github.com/Azure/data-api-builder/assets/3513779/5a80f62e-8a06-4e7c-aa22-c120dade6801)

Author: Aniruddh25

src/Cli/ConfigGenerator.cs

@@ -948,7 +948,7 @@ public static bool VerifyCanUpdateRelationship(RuntimeConfig runtimeConfig, stri
         /// It will use the config provided by the user, else based on the environment value
         /// it will either merge the config if base config and environmentConfig is present
         /// else it will choose a single config based on precedence (left to right) of
-        /// overrides < environmentConfig < defaultConfig
+        /// overrides > environmentConfig > defaultConfig
         /// Also preforms validation to check connection string is not null or empty.
         /// </summary>
         public static bool TryStartEngineWithOptions(StartOptions options, FileSystemRuntimeConfigLoader loader, IFileSystem fileSystem)
@@ -965,15 +965,19 @@ public static bool TryStartEngineWithOptions(StartOptions options, FileSystemRun
                 return false;
             }
 
-            loader.UpdateBaseConfigFileName(runtimeConfigFile);
+            loader.UpdateConfigFileName(runtimeConfigFile);
 
             // Validates that config file has data and follows the correct json schema
             // Replaces all the environment variables while deserializing when starting DAB.
             if (!loader.TryLoadKnownConfig(out RuntimeConfig? deserializedRuntimeConfig, replaceEnvVar: true))
             {
-                _logger.LogError("Failed to parse the config file: {configFile}.", runtimeConfigFile);
+                _logger.LogError("Failed to parse the config file: {runtimeConfigFile}.", runtimeConfigFile);
                 return false;
             }
+            else
+            {
+                _logger.LogInformation("Loaded config file: {runtimeConfigFile}", runtimeConfigFile);
+            }
 
             if (string.IsNullOrWhiteSpace(deserializedRuntimeConfig.DataSource.ConnectionString))
             {

src/Config/FileSystemRuntimeConfigLoader.cs

@@ -25,6 +25,8 @@ namespace Azure.DataApiBuilder.Config;
 /// </remarks>
 public class FileSystemRuntimeConfigLoader : RuntimeConfigLoader
 {
+    // This stores either the default config name e.g. dab-config.json
+    // or user provided config file.
     private string _baseConfigFileName;
 
     private readonly IFileSystem _fileSystem;
@@ -42,13 +44,20 @@ public class FileSystemRuntimeConfigLoader : RuntimeConfigLoader
     /// </summary>
     public const string DEFAULT_CONFIG_FILE_NAME = $"{CONFIGFILE_NAME}{CONFIG_EXTENSION}";
 
-    public string ConfigFileName => GetFileNameForEnvironment(Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT"), false);
+    /// <summary>
+    /// Stores the config file name actually loaded by the engine.
+    /// It could be the base config file (e.g. dab-config.json), any of its derivatives with
+    /// environment specific suffixes (e.g. dab-config.Development.json) or the user provided
+    /// config file name.
+    /// </summary>
+    public string ConfigFileName { get; internal set; }
 
     public FileSystemRuntimeConfigLoader(IFileSystem fileSystem, string baseConfigFileName = DEFAULT_CONFIG_FILE_NAME, string? connectionString = null)
         : base(connectionString)
     {
         _fileSystem = fileSystem;
         _baseConfigFileName = baseConfigFileName;
+        ConfigFileName = GetFileNameForEnvironment(Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT"), false);
     }
 
     /// <summary>
@@ -69,6 +78,12 @@ public bool TryLoadConfig(
             string json = _fileSystem.File.ReadAllText(path);
             return TryParseConfig(json, out config, connectionString: _connectionString, replaceEnvVar: replaceEnvVar);
         }
+        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.");
+        }
 
         config = null;
         return false;
@@ -178,21 +193,7 @@ public static string GetEnvironmentFileName(string fileName, string environmentV
     public bool DoesFileExistInCurrentDirectory(string fileName)
     {
         string currentDir = _fileSystem.Directory.GetCurrentDirectory();
-        // Unable to use ILogger because this code is invoked before LoggerFactory
-        // is instantiated.
-        if (_fileSystem.File.Exists(_fileSystem.Path.Combine(currentDir, fileName)))
-        {
-            // This config file is logged as being found, but may not actually be used!
-            Console.WriteLine($"Found config file: {fileName}.");
-            return true;
-        }
-        else
-        {
-            // Unable to use ILogger because this code is invoked before LoggerFactory
-            // is instantiated.
-            Console.WriteLine($"Unable to find config file: {fileName} does not exist.");
-            return false;
-        }
+        return _fileSystem.File.Exists(_fileSystem.Path.Combine(currentDir, fileName));
     }
 
     /// <summary>
@@ -251,11 +252,13 @@ public static string GetMergedFileNameForEnvironment(string fileName, string env
     }
 
     /// <summary>
-    /// Allows the base config file name to be updated. This is commonly done when the CLI is starting up.
+    /// Allows the base config file and the actually loaded config file name(tracked by the property ConfigFileName)
+    /// to be updated. This is commonly done when the CLI is starting up.
     /// </summary>
     /// <param name="fileName"></param>
-    public void UpdateBaseConfigFileName(string fileName)
+    public void UpdateConfigFileName(string fileName)
     {
         _baseConfigFileName = fileName;
+        ConfigFileName = fileName;
     }
 }

src/Service.Tests/Configuration/AuthenticationConfigValidatorUnitTests.cs

@@ -45,6 +45,10 @@ public void ValidateEasyAuthConfig()
                 new MockFileData(config.ToJson())
             );
 
+            // Since we added the config file to the filesystem above after the config loader was initialized
+            // in TestInitialize, we need to update the ConfigfileName, otherwise it will be an empty string.
+            _runtimeConfigLoader.UpdateConfigFileName(FileSystemRuntimeConfigLoader.DEFAULT_CONFIG_FILE_NAME);
+
             try
             {
                 _runtimeConfigValidator.ValidateConfig();
@@ -71,6 +75,8 @@ public void ValidateJwtConfigParamsSet()
                 new MockFileData(config.ToJson())
             );
 
+            _runtimeConfigLoader.UpdateConfigFileName(FileSystemRuntimeConfigLoader.DEFAULT_CONFIG_FILE_NAME);
+
             try
             {
                 _runtimeConfigValidator.ValidateConfig();
@@ -90,6 +96,8 @@ public void ValidateAuthNSectionNotNecessary()
                 new MockFileData(config.ToJson())
             );
 
+            _runtimeConfigLoader.UpdateConfigFileName(FileSystemRuntimeConfigLoader.DEFAULT_CONFIG_FILE_NAME);
+
             try
             {
                 _runtimeConfigValidator.ValidateConfig();
@@ -117,6 +125,8 @@ public void ValidateFailureWithIncompleteJwtConfig()
                 new MockFileData(config.ToJson())
             );
 
+            _runtimeConfigLoader.UpdateConfigFileName(FileSystemRuntimeConfigLoader.DEFAULT_CONFIG_FILE_NAME);
+
             Assert.ThrowsException<NotSupportedException>(() =>
             {
                 _runtimeConfigValidator.ValidateConfig();
@@ -150,6 +160,8 @@ public void ValidateFailureWithUnneededEasyAuthConfig()
                 new MockFileData(config.ToJson())
             );
 
+            _runtimeConfigLoader.UpdateConfigFileName(FileSystemRuntimeConfigLoader.DEFAULT_CONFIG_FILE_NAME);
+
             Assert.ThrowsException<NotSupportedException>(() =>
             {
                 _runtimeConfigValidator.ValidateConfig();

src/Service/Startup.cs

@@ -294,10 +294,6 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env, RuntimeC
             {
                 // Config provided before starting the engine.
                 isRuntimeReady = PerformOnConfigChangeAsync(app).Result;
-                if (_logger is not null)
-                {
-                    _logger.LogDebug("Loaded config file from {filePath}", fileSystemRuntimeConfigLoader.ConfigFileName);
-                }
 
                 if (!isRuntimeReady)
                 {