Adds the RewritePlugin. Closes #926 (#933)

Author: waldekmastykarz

dev-proxy-abstractions/IProxyLogger.cs

@@ -17,7 +17,8 @@ public enum MessageType
     Mocked,
     InterceptedResponse,
     FinishedProcessingRequest,
-    Skipped
+    Skipped,
+    Processed
 }
 
 public class LoggingContext(SessionEventArgs session)

dev-proxy-plugins/Processing/RewritePlugin.cs

@@ -0,0 +1,93 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+using Microsoft.DevProxy.Abstractions;
+using System.Text.RegularExpressions;
+
+namespace Microsoft.DevProxy.Plugins.Processing;
+
+public class RewriteRule
+{
+    public string? Url { get; set; }
+}
+
+public class RequestRewrite
+{
+    public RewriteRule? In { get; set; }
+    public RewriteRule? Out { get; set; }
+}
+
+public class RewritePluginConfiguration
+{
+    public IEnumerable<RequestRewrite> Rewrites { get; set; } = [];
+    public string RewritesFile { get; set; } = "rewrites.json";
+}
+
+public class RewritePlugin(IPluginEvents pluginEvents, IProxyContext context, ILogger logger, ISet<UrlToWatch> urlsToWatch, IConfigurationSection? configSection = null) : BaseProxyPlugin(pluginEvents, context, logger, urlsToWatch, configSection)
+{
+    public override string Name => nameof(RewritePlugin);
+    private readonly RewritePluginConfiguration _configuration = new();
+    private RewritesLoader? _loader = null;
+
+    public override async Task RegisterAsync()
+    {
+        await base.RegisterAsync();
+
+        ConfigSection?.Bind(_configuration);
+        _loader = new RewritesLoader(Logger, _configuration);
+
+        PluginEvents.BeforeRequest += BeforeRequestAsync;
+
+        // make the rewrites file path relative to the configuration file
+        _configuration.RewritesFile = Path.GetFullPath(
+            ProxyUtils.ReplacePathTokens(_configuration.RewritesFile),
+            Path.GetDirectoryName(Context.Configuration.ConfigFile ?? string.Empty) ?? string.Empty
+        );
+
+        _loader?.InitResponsesWatcher();
+    }
+
+    private Task BeforeRequestAsync(object sender, ProxyRequestArgs e)
+    {
+        if (UrlsToWatch is null ||
+            !e.HasRequestUrlMatch(UrlsToWatch))
+        {
+            Logger.LogRequest("URL not matched", MessageType.Skipped, new LoggingContext(e.Session));
+            return Task.CompletedTask;
+        }
+
+        if (_configuration.Rewrites is null ||
+            !_configuration.Rewrites.Any())
+        {
+            Logger.LogRequest("No rewrites configured", MessageType.Skipped, new LoggingContext(e.Session));
+            return Task.CompletedTask;
+        }
+
+        var request = e.Session.HttpClient.Request;
+
+        foreach (var rewrite in _configuration.Rewrites)
+        {
+            if (string.IsNullOrEmpty(rewrite.In?.Url) ||
+                string.IsNullOrEmpty(rewrite.Out?.Url))
+            {
+                continue;
+            }
+
+            var newUrl = Regex.Replace(request.Url, rewrite.In.Url, rewrite.Out.Url, RegexOptions.IgnoreCase);
+
+            if (request.Url.Equals(newUrl, StringComparison.OrdinalIgnoreCase))
+            {
+                Logger.LogRequest($"{rewrite.In?.Url}", MessageType.Skipped, new LoggingContext(e.Session));
+            }
+            else
+            {
+                Logger.LogRequest($"{rewrite.In?.Url} > {newUrl}", MessageType.Processed, new LoggingContext(e.Session));
+                request.Url = newUrl;
+            }
+        }
+
+        return Task.CompletedTask;
+    }
+}

dev-proxy-plugins/Processing/RewritesLoader.cs

@@ -0,0 +1,87 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.DevProxy.Abstractions;
+using Microsoft.Extensions.Logging;
+using System.Text.Json;
+
+namespace Microsoft.DevProxy.Plugins.Processing;
+
+internal class RewritesLoader(ILogger logger, RewritePluginConfiguration configuration) : IDisposable
+{
+    private readonly ILogger _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    private readonly RewritePluginConfiguration _configuration = configuration ?? throw new ArgumentNullException(nameof(configuration));
+
+    private string RewritesFilePath => _configuration.RewritesFile;
+    private FileSystemWatcher? _watcher;
+
+    public void LoadRewrites()
+    {
+        if (!File.Exists(RewritesFilePath))
+        {
+            _logger.LogWarning("File {configurationFile} not found. No rewrites will be provided", _configuration.RewritesFile);
+            _configuration.Rewrites = [];
+            return;
+        }
+
+        try
+        {
+            using var stream = new FileStream(RewritesFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
+            using var reader = new StreamReader(stream);
+            var RewritesString = reader.ReadToEnd();
+            var rewritesConfig = JsonSerializer.Deserialize<RewritePluginConfiguration>(RewritesString, ProxyUtils.JsonSerializerOptions);
+            IEnumerable<RequestRewrite>? configRewrites = rewritesConfig?.Rewrites;
+            if (configRewrites is not null)
+            {
+                _configuration.Rewrites = configRewrites;
+                _logger.LogInformation("Rewrites for {configResponseCount} url patterns loaded from {RewritesFile}", configRewrites.Count(), _configuration.RewritesFile);
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "An error has occurred while reading {RewritesFile}:", _configuration.RewritesFile);
+        }
+    }
+
+    public void InitResponsesWatcher()
+    {
+        if (_watcher is not null)
+        {
+            return;
+        }
+
+        string path = Path.GetDirectoryName(RewritesFilePath) ?? throw new InvalidOperationException($"{RewritesFilePath} is an invalid path");
+        if (!File.Exists(RewritesFilePath))
+        {
+            _logger.LogWarning("File {RewritesFile} not found. No rewrites will be provided", _configuration.RewritesFile);
+            _configuration.Rewrites = [];
+            return;
+        }
+
+        _watcher = new FileSystemWatcher(Path.GetFullPath(path))
+        {
+            NotifyFilter = NotifyFilters.CreationTime
+                             | NotifyFilters.FileName
+                             | NotifyFilters.LastWrite
+                             | NotifyFilters.Size,
+            Filter = Path.GetFileName(RewritesFilePath)
+        };
+        _watcher.Changed += ResponsesFile_Changed;
+        _watcher.Created += ResponsesFile_Changed;
+        _watcher.Deleted += ResponsesFile_Changed;
+        _watcher.Renamed += ResponsesFile_Changed;
+        _watcher.EnableRaisingEvents = true;
+
+        LoadRewrites();
+    }
+
+    private void ResponsesFile_Changed(object sender, FileSystemEventArgs e)
+    {
+        LoadRewrites();
+    }
+
+    public void Dispose()
+    {
+        _watcher?.Dispose();
+    }
+}

dev-proxy/Logging/ProxyConsoleFormatter.cs

@@ -230,13 +230,14 @@ private static string GetMessageTypeString(MessageType messageType)
         {
             MessageType.InterceptedRequest => "req",
             MessageType.InterceptedResponse => "res",
-            MessageType.PassedThrough => "api",
+            MessageType.PassedThrough => "pass",
             MessageType.Chaos => "oops",
             MessageType.Warning => "warn",
             MessageType.Mocked => "mock",
             MessageType.Failed => "fail",
             MessageType.Tip => "tip",
             MessageType.Skipped => "skip",
+            MessageType.Processed => "proc",
             _ => "    "
         };
     }
@@ -251,6 +252,7 @@ private static (ConsoleColor bg, ConsoleColor fg) GetMessageTypeColor(MessageTyp
             MessageType.InterceptedRequest => (bgColor, ConsoleColor.Gray),
             MessageType.PassedThrough => (ConsoleColor.Gray, fgColor),
             MessageType.Skipped => (bgColor, ConsoleColor.Gray),
+            MessageType.Processed => (ConsoleColor.DarkGreen, fgColor),
             MessageType.Chaos => (ConsoleColor.DarkRed, fgColor),
             MessageType.Warning => (ConsoleColor.DarkYellow, fgColor),
             MessageType.Mocked => (ConsoleColor.DarkMagenta, fgColor),

schemas/v0.23.0/rewriteplugin.schema.json

@@ -0,0 +1,44 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "title": "Dev Proxy RewritePlugin rewrite rules",
+  "description": "Rewrite rules for the Dev Proxy RewritePlugin",
+  "type": "object",
+  "properties": {
+    "$schema": {
+      "type": "string"
+    },
+    "rewrites": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "properties": {
+          "in": {
+            "type": "object",
+            "properties": {
+              "url": {
+                "type": "string",
+                "pattern": "^.+$"
+              }
+            },
+            "required": ["url"]
+          },
+          "out": {
+            "type": "object",
+            "properties": {
+              "url": {
+                "type": "string",
+                "pattern": "^.*$"
+              }
+            },
+            "required": ["url"]
+          }
+        },
+        "required": ["in", "out"]
+      }
+    }
+  },
+  "required": [
+    "rewrites"
+  ],
+  "additionalProperties": false
+}