Unobtanium migration #1369

svrooij · 2025-08-21T16:43:59Z

A new proxy backend and a new control flow, each plugin can decide to return a response.

This is a work-in-progress, looking for feedback. Everything changed and not everything is fixed but I think it is the way to go.

Still has several // TODO: … notes in the code, but it builds and runs 🤯

Discuss

Control flow

The next proxy has two entry points OnRequest and OnResponse. The OnRequest event has to be answered with ModifyRequest, EarlyResponse or Continue. This means that the first plugin that wants to send a response can do do just that.

This also means there is not session or state to modify. The plugin can decide to answer or do nothing. I've split guidance plugins (which will always receive the request since they were not modifying it anyway), from modifying plugins. With the latter if the requests reached that plugin it is not modified before, no need to check if it is modified, just decide what to do.

Is this way workable? This will make the order in which the plugins are added important.

DevTools plugin

I seem to be doing something wrong, there is no longer any log in the console of the DevTools plugin

Plugins in general

Plugins can implement the any of the plugin functions, which are all optional, which means the ProxyEngine can select just the plugins that implement that function.

Plugin URLS

Maybe plugins should optionally have a list of urls for that plugin. Then we could skip plugins that don't do stuff with the current url.

…tion guide

Copilot

Pull Request Overview

This PR migrates the Dev Proxy from the Titanium.Web.Proxy library to the new Unobtanium.Web.Proxy library, introducing a functional plugin API to replace the previous event-based system. The migration includes updated proxy backend infrastructure, new control flow patterns where plugins can return responses directly, and comprehensive telemetry integration with OpenTelemetry.

Key changes:

Complete replacement of Titanium.Web.Proxy with Unobtanium.Web.Proxy (0.9.1-beta-2)
Introduction of functional plugin API methods (OnRequestAsync, OnRequestLogAsync, OnResponseAsync, OnResponseLogAsync)
New proxy storage system with IProxyStorage interface for global and request-specific data
Enhanced OpenTelemetry integration for distributed tracing and metrics

Reviewed Changes

Copilot reviewed 82 out of 82 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
DevProxy/packages.lock.json	Updated Unobtanium.Web.Proxy to 0.9.1-beta-2 and added OpenTelemetry packages
DevProxy/Proxy/ProxyEngine.cs	Complete rewrite using new Unobtanium proxy events and functional plugin architecture
DevProxy/Proxy/EfficientProxyHttpClientFactory.cs	New HTTP client factory for efficient port reuse
DevProxy/Proxy/CertificateDiskCache.cs	Removed (replaced by Unobtanium certificate management)
DevProxy/Program.cs	Added Unobtanium proxy services and OpenTelemetry configuration
DevProxy/Plugins/ProxyStorage.cs	New storage implementation for global and request-specific plugin data
DevProxy/Extensions/IServiceCollectionExtensions.cs	Added proxy services, HTTP client factory, and OpenTelemetry configuration
DevProxy.Plugins/migration.md	Comprehensive migration guide for plugin developers
DevProxy.Plugins/inventory.md	Complete inventory of existing plugins and their migration status
DevProxy.Plugins/Mocking/*.cs	Multiple plugins migrated to new functional API
DevProxy.Plugins/Reporting/*.cs	Reporting plugins updated to use new IProxyStorage interface

Copilot · 2025-08-21T16:45:12Z

DevProxy/Logging/ProxyConsoleFormatter.cs

+        if (string.IsNullOrEmpty(requestId) || textWriter is null)
+        {
+            return;
+        }


The textWriter null check is redundant since the method parameter is not nullable. Consider removing the '|| textWriter is null' condition or making the parameter nullable if null values are expected.

Suggested change

}

if (string.IsNullOrEmpty(requestId))

{

return;

}

Copilot · 2025-08-21T16:45:13Z

DevProxy.Plugins/Utils/MinimalPermissionsUtils.cs

-            var token = jwtToken.Split(' ')[1];
+            var token = jwtToken!.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase)
+                ? jwtToken["Bearer ".Length..].Trim()
+                : jwtToken.Trim();


The code uses a magic string 'Bearer ' twice. Consider extracting this to a constant for better maintainability: const string BearerPrefix = \"Bearer \";

Suggested change

: jwtToken.Trim();

var token = jwtToken!.StartsWith(BearerPrefix, StringComparison.OrdinalIgnoreCase)

? jwtToken[BearerPrefix.Length..].Trim()

: jwtToken.Trim();

Copilot · 2025-08-21T16:45:13Z

DevProxy.Plugins/Mocking/CrudApiPlugin.cs

@@ -221,7 +205,7 @@ private void LoadData()
        }
    }

-    private (Action<SessionEventArgs, CrudApiAction, IDictionary<string, string>> handler, CrudApiAction action, IDictionary<string, string> parameters)? GetMatchingActionHandler(Request request)
+    private (Func<HttpRequestMessage, CrudApiAction, IDictionary<string, string>, CancellationToken, Task<HttpResponseMessage>> handler, CrudApiAction action, IDictionary<string, string> parameters)? GetMatchingActionHandler(HttpRequestMessage request)
    {


The method signature is extremely long and complex. Consider extracting the Func delegate to a separate type alias or interface to improve readability: private delegate Task<HttpResponseMessage> ActionHandler(HttpRequestMessage request, CrudApiAction action, IDictionary<string, string> parameters, CancellationToken cancellationToken);

Suggested change

{

// Delegate type for action handlers to improve readability

private delegate Task<HttpResponseMessage> ActionHandler(HttpRequestMessage request, CrudApiAction action, IDictionary<string, string> parameters, CancellationToken cancellationToken);

private (ActionHandler handler, CrudApiAction action, IDictionary<string, string> parameters)? GetMatchingActionHandler(HttpRequestMessage request)

{

DevProxy.Plugins/Mocking/CrudApiPlugin.cs

-            new("content-type", "application/json; charset=utf-8")
+        var response = new HttpResponseMessage(statusCode)
+        {
+            Content = new StringContent(body, Encoding.UTF8, "application/json")


waldekmastykarz · 2025-08-26T05:57:11Z

Awesome! As it's WIP, let's mark it as draft so that we won't merge it just yet

garrytrinder · 2025-09-08T08:52:04Z

Thanks for the PR @svrooij awesome work 👏

A few comments from me:

Control flow

Is this way workable? This will make the order in which the plugins are added important.

The order in which the plugins are defined in the config file is important today, for example, if you don't put a reporter plugin after a plugin that generates a report then you won't get any output.

Plugin URLS
Maybe plugins should optionally have a list of urls for that plugin. Then we could skip plugins that don't do stuff with the current url.

All plugins can have urlToWatch defined on the plugin instance, this overrides the global urlsToWatch.

waldekmastykarz · 2025-09-09T06:37:20Z

DevProxy.Abstractions/Plugins/BasePlugin.cs

-    public virtual Option[] GetOptions() => [];
-    public virtual Command[] GetCommands() => [];
+    /// <inheritdoc/>
+    public virtual Func<RequestArguments, CancellationToken, Task>? ProvideRequestGuidanceAsync { get; }


What's the benefit of using delegates vs. virtual methods that we can override? Since we need to implement the logic anyway, isn't using a delegate an unnecessary complexity? Ie. I need to implement the method and add a reference to it in the delegate.

The benefit is performance, before calling the plugin we already know if it implemented this. So in the ProxyEngine it skips plugins that did not implement this. We can do the null check on the function, instead of the base plugin returning completed task

And on the other hand, this way we force the plugin to think about what it is doing next, early response/modify request/continue as normal.

waldekmastykarz · 2025-09-09T06:39:40Z

DevProxy.Abstractions/Utils/ProxyUtils.cs

@@ -158,7 +157,7 @@ public static IList<MockResponseHeader> BuildGraphResponseHeaders(Request reques
                new ("Date", requestDate),
                new ("Content-Type", "application/json")
            };
-        if (request.Headers.FirstOrDefault((h) => h.Name.Equals("Origin", StringComparison.OrdinalIgnoreCase)) is not null)
+        if (request.Headers.Contains("Origin"))


Is this comparison case-insensitive?

According to the http specs the headers should be case insensitive, but they come through as they come through. Kestrel parses them to an actual object no matter the casing. So I thought let's make it case insensitive here as well.

No you're right that might be a mistake, let me check

waldekmastykarz · 2025-09-09T11:11:56Z

DevProxy.Plugins/Reporting/UrlDiscoveryPlugin.cs

@@ -28,19 +29,18 @@ public override Task AfterRecordingStopAsync(RecordingArgs e, CancellationToken
        }

        var requestLogs = e.RequestLogs
-            .Where(l => ProxyUtils.MatchesUrlToWatch(UrlsToWatch, l.Context?.Session.HttpClient.Request.RequestUri.AbsoluteUri ?? ""));
+            .Where(l => ProxyUtils.MatchesUrlToWatch(UrlsToWatch, l.Request!.RequestUri!.AbsoluteUri ?? ""));


The !. looks a bit messy. If it can be null, we need to do more robust checks to avoid runtime failures.

svrooij added 10 commits August 8, 2025 14:34

Initial migration attempt

256b9c4

Main proxy migration

331a9e8

First plugin migrated

0633c3b

Added log-only methods in interface and generated inventory and migra…

e107b22

…tion guide

Guidance plugins migrated

1d87e56

More plugins migrated

81f0ad6

Two more plugins migrated

874f437

Reporters fixed

e4ad26f

Almost there

7544807

Migration done?? 🏁

f66346d

Copilot AI review requested due to automatic review settings August 21, 2025 16:44

svrooij requested a review from a team as a code owner August 21, 2025 16:44

Copilot AI reviewed Aug 21, 2025

View reviewed changes

Merge branch 'main' into unobtanium-migration

fe4c35d

github-advanced-security bot found potential problems Aug 22, 2025

View reviewed changes

svrooij added 2 commits August 22, 2025 16:10

fix: DevTools response body

f14c3b3

More logging

013919b

waldekmastykarz marked this pull request as draft August 26, 2025 05:57

svrooij added 2 commits August 26, 2025 16:55

Docs and rename method

49b9bbc

Plugin method rename

806eb9f

waldekmastykarz reviewed Sep 9, 2025

View reviewed changes

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Unobtanium migration #1369

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svrooij commented Aug 21, 2025 •

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-        }
+        if (string.IsNullOrEmpty(requestId))
+        {
+            return;
+        }

-    {
+    // Delegate type for action handlers to improve readability
+    private delegate Task<HttpResponseMessage> ActionHandler(HttpRequestMessage request, CrudApiAction action, IDictionary<string, string> parameters, CancellationToken cancellationToken);
+    private (ActionHandler handler, CrudApiAction action, IDictionary<string, string> parameters)? GetMatchingActionHandler(HttpRequestMessage request)
+    {

Unobtanium migration #1369

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Control flow

DevTools plugin

Plugins in general

Plugin URLS

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Pull Request Overview

Reviewed Changes

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waldekmastykarz commented Aug 26, 2025

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svrooij commented Aug 21, 2025 •

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