perf: replace http-proxy with fast-proxy + undici

[betschki]

Significantly improved proxy performance by switching from http-proxy to fast-proxy with undici backend. Proxy overhead reduced from 120-286ms to near-zero through connection pooling and HTTP pipelining.

• Add fast-proxy and undici dependencies
• Rewrite middleware.ts to use fast-proxy with undici
• Configure 100 persistent connections with HTTP pipelining
• Add URL caching for 1000 parsed URLs
• Remove http-proxy and related type dependencies
• Bump version to 1.3.0

Summary by CodeRabbit

• New Features

  • HTTP request pipelining support (10 concurrent requests)
  • Connection pooling for optimized request handling (100 connections)
  • URL caching for faster processing (1,000 entries)

• Bug Fixes

  • Enhanced error handling with improved error page display

• Chores

  • Release v1.3.0

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[coderabbitai]

Caution

Review failed

The pull request is closed.

Walkthrough

Package version bumped to 1.3.0 with http-proxy replaced by fast-proxy and undici for improved performance. Updated middleware implements new request/response header rewriting logic, enhanced error handling with static HTML pages, and introduces a public close method for connection management.

Changes

Cohort / File(s)	Summary
Version & Dependency Updates package.json	Version bumped 1.2.0 → 1.3.0; removed http-proxy, @types/http-proxy, @types/http-proxy-middleware; added fast-proxy and undici
Release Documentation CHANGELOG.md	New 1.3.0 entry documenting http-proxy → fast-proxy/undici migration, connection pooling (100), HTTP pipelining (10 deep), and URL caching (1000 entries)
Proxy Implementation src/middleware.ts	Major refactoring: replaced http-proxy with fast-proxy; new header rewriting (x-forwarded-for, x-real-ip), cache invalidation detection; improved error handling with static HTML pages; added public close() method; removed event listeners and direct piping

Sequence Diagram

sequenceDiagram
    participant Client
    participant Middleware as ProxyMiddleware
    participant FastProxy as fast-proxy
    participant Backend

    Client->>Middleware: HTTP Request
    activate Middleware
    Middleware->>Middleware: rewriteRequestHeaders<br/>(x-forwarded-for, x-real-ip)
    Middleware->>FastProxy: proxyFn(request, rewrite hooks)
    activate FastProxy
    FastProxy->>Backend: Forward with<br/>rewritten headers
    activate Backend
    Backend-->>FastProxy: HTTP Response
    deactivate Backend
    FastProxy->>Middleware: Response headers
    Middleware->>Middleware: rewriteHeaders<br/>(detect x-cache-invalidate,<br/>filter sensitive headers)
    Middleware-->>Client: Response
    deactivate FastProxy
    deactivate Middleware
    
    Note over Middleware: On error: handleProxyError<br/>renders static HTML page

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

• src/middleware.ts: Critical focus area—significant logic refactoring with new header rewriting, error handling, and close management. Verify x-forwarded-for/x-real-ip computation logic, cache invalidation detection, and error page rendering conditions.
• Fast-proxy integration: Confirm proper initialization via createRequire and rewrite hook lifecycle.
• Type definitions: Validate new FastProxyOptions and ProxyFunction types align with fast-proxy API.

Poem

🐰 A proxy swift, with wings so fast,
Fast-proxy soars where old ones passed,
Undici's pool flows deep and wide,
Headers rewritten, clients worldwide,
Connection pooling—performance's pride! ✨

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch switch-proxy

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📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between af220ae and 57a4655.

⛔ Files ignored due to path filters (2)

• package-lock.json is excluded by !**/package-lock.json
• yarn.lock is excluded by !**/yarn.lock, !**/*.lock

📒 Files selected for processing (3)

• CHANGELOG.md (1 hunks)
• package.json (2 hunks)
• src/middleware.ts (2 hunks)

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