Adds support for specifying the config file name. Closes #228 (#229)

Adds support for specifying the config file name. Closes #228 (#229)

Author: waldekmastykarz

.vscode/launch.json

@@ -12,7 +12,7 @@
       // If you have changed target frameworks, make sure to update the program path.
       "program": "${workspaceFolder}/msgraph-developer-proxy/bin/Debug/net7.0/mgdp.dll",
       "args": [],
-      "cwd": "${workspaceFolder}/msgraph-developer-proxy",
+      "cwd": "${workspaceFolder}/msgraph-developer-proxy/bin/Debug/net7.0",
       // For more information about the 'console' field, see https://aka.ms/VSCode-CS-LaunchJson-Console
       "console": "integratedTerminal",
       "stopAtEntry": false,

msgraph-developer-proxy/PluginLoader.cs

@@ -92,7 +92,7 @@ private PluginConfig PluginConfig {
 
     private readonly Lazy<IConfigurationRoot> ConfigurationFactory = new(() =>
         new ConfigurationBuilder()
-                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
+                .AddJsonFile(ProxyHost.ConfigFile, optional: true, reloadOnChange: true)
                 .Build()
     );
 }

msgraph-developer-proxy/ProxyCommandHandler.cs

@@ -91,7 +91,7 @@ public async Task<int> InvokeAsync(InvocationContext context) {
     private static readonly Lazy<ProxyConfiguration> ConfigurationFactory = new(() => {
         var builder = new ConfigurationBuilder();
         var configuration = builder
-                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
+                .AddJsonFile(ProxyHost.ConfigFile, optional: true, reloadOnChange: true)
                 .Build();
         var configObject = new ProxyConfiguration();
         configuration.Bind(configObject);

msgraph-developer-proxy/ProxyHost.cs

@@ -11,6 +11,43 @@ internal class ProxyHost {
     private Option<int?> _portOption;
     private Option<LogLevel?> _logLevelOption;
     private Option<bool?> _recordOption;
+    private static Option<string?>? _configFileOption;
+
+    private static bool _configFileResolved = false;
+    private static string _configFile = "appsettings.json";
+    public static string ConfigFile {
+        get {
+            if (_configFileResolved) {
+                return _configFile;
+            }
+            
+            if (_configFileOption is null) {
+                _configFileOption = new Option<string?>("--config-file", "The path to the configuration file");
+                _configFileOption.AddAlias("-c");
+                _configFileOption.ArgumentHelpName = "configFile";
+                _configFileOption.AddValidator(input => {
+                    var filePath = input.Tokens.First().Value;
+                    if (String.IsNullOrEmpty(filePath)) {
+                        return;
+                    }
+
+                    if (!File.Exists(filePath)) {
+                        input.ErrorMessage = $"File {filePath} does not exist";
+                    }
+                });
+            }
+
+            var result = _configFileOption.Parse(Environment.GetCommandLineArgs());
+            var configFile = result.GetValueForOption<string?>(_configFileOption);
+            if (configFile is not null) {
+                _configFile = configFile;
+            }
+
+            _configFileResolved = true;
+
+            return _configFile;
+        }
+    }
 
     public ProxyHost() {
         _portOption = new Option<int?>("--port", "The port for the proxy server to listen on");
@@ -32,7 +69,10 @@ public RootCommand GetRootCommand() {
         var command = new RootCommand {
             _portOption,
             _logLevelOption,
-            _recordOption
+            _recordOption,
+            // _configFileOption is set during the call to load
+            // `ProxyCommandHandler.Configuration`. As such, it's always set here
+            _configFileOption!
         };
         command.Description = "Microsoft Graph Developer Proxy is a command line tool that simulates real world behaviors of Microsoft Graph and other APIs, locally.";