Asgiri

A high-performance ASGI server implementation supporting HTTP/1.1, HTTP/2, and HTTP/3 protocols with automatic protocol detection and seamless switching.

Features

• Multi-Protocol Support: Handles HTTP/1.1, HTTP/2, and HTTP/3 on the same port
• HTTP/3 (QUIC): Modern UDP-based protocol for improved performance over lossy networks
• Auto-Detection: Automatically detects client protocol preference
• Dual Transport: Runs TCP and UDP servers simultaneously for comprehensive protocol coverage
• Protocol Advertisement: Advertises HTTP/2 and HTTP/3 capability via Alt-Svc headers
• WebSocket Support: WebSocket protocol over HTTP/1.1 and HTTP/2
• ASGI 3.0 Compatible: Works with any ASGI 3.0 application
• Async/Await: Built on Python's asyncio for high concurrency
• Multiprocessing: Run multiple worker processes with SO_REUSEPORT for better CPU utilization

Lore

Deep in the hills of Kandy, Sri Lanka, stands the Asgiri Maha Viharaya — a sacred monastery that has been a beacon of wisdom and preservation for centuries. As the headquarters of the Asgiriya Chapter of Siyam Nikaya, this ancient temple holds the solemn duty of safeguarding one of Buddhism's most precious relics: the sacred tooth relic of Buddha.

Just as the monastery has faithfully served countless pilgrims across the ages, handling their requests with grace and precision, so too does this server aim to serve your web traffic. Like the monks who maintain both ancient traditions (the sacred tooth relic) and adapt to modern times, Asgiri the server bridges the old (HTTP/1.1), the new (HTTP/2), and the cutting edge (HTTP/3), automatically detecting which protocol each client speaks and responding with wisdom.

The name asgiri reminds us that good software, like good monasteries, should be:

• Reliable — Standing strong through the centuries
• Adaptable — Serving all who come, regardless of their background
• Efficient — Handling many requests with minimal resources
• Graceful — Switching protocols as smoothly as monks switch between prayer and teaching

May your servers run as peacefully as the chants in Asgiri's halls. 🙏

Quick Start

from asgiri.server import Server

async def app(scope, receive, send):
    await send({
        "type": "http.response.start",
        "status": 200,
        "headers": [(b"content-type", b"text/plain")],
    })
    await send({
        "type": "http.response.body",
        "body": b"Hello, World!",
    })

server = Server(app=app, host="127.0.0.1", port=8000)
server.run()

Protocol Support

Auto-Detection (Default)

By default, the server automatically detects whether the client is using HTTP/1.1, HTTP/2, or HTTP/3:

server = Server(app=app, host="127.0.0.1", port=8443, certfile="cert.pem", keyfile="key.pem")
# Automatically handles HTTP/1.1, HTTP/2 (TCP), and HTTP/3 (UDP)

Explicit Protocol Selection

You can force a specific protocol if needed:

from asgiri.server import HttpProtocolVersion

# HTTP/1.1 only
server = Server(app=app, http_version=HttpProtocolVersion.HTTP_1_1)

# HTTP/2 only
server = Server(app=app, http_version=HttpProtocolVersion.HTTP_2)

# HTTP/3 only (requires TLS)
server = Server(
    app=app, 
    http_version=HttpProtocolVersion.HTTP_3,
    certfile="cert.pem",
    keyfile="key.pem"
)

# Auto-detection (explicit)
server = Server(app=app, http_version=HttpProtocolVersion.AUTO)

HTTP/3 Configuration

HTTP/3 requires TLS certificates:

from asgiri.server import Server

server = Server(
    app=app,
    host="0.0.0.0",
    port=8443,
    certfile="cert.pem",
    keyfile="key.pem",
    enable_http3=True,  # Enable HTTP/3 (default: True)
)

Multiprocessing with Multiple Workers

Run multiple worker processes using SO_REUSEPORT to share the same port:

⚠️ Important: HTTP/3 is not compatible with multi-worker mode due to UDP socket sharing limitations. When using reuse_port=True or --workers > 1, HTTP/3 will be automatically disabled. For HTTP/3 load balancing, use a reverse proxy like nginx or HAProxy.

# Single worker (default)
python -m asgiri --workers 1 myapp:app

# Multiple workers (e.g., 4 workers) - HTTP/3 automatically disabled
python -m asgiri --workers 4 myapp:app

# Auto-detect CPU count
python -m asgiri --workers auto myapp:app

Or programmatically:

from asgiri.server import Server
from asgiri.multiprocessing_workers import spawn_workers

def create_server():
    server = Server(
        app=app,
        host="0.0.0.0",
        port=8000,
        reuse_port=True,  # Required for multiprocessing - HTTP/3 disabled
    )
    server.run()

# Run with 4 workers
spawn_workers(4, create_server)

Note: When using multiple workers (workers > 1), SO_REUSEPORT is automatically enabled. This allows multiple processes to bind to the same port, with the kernel load-balancing incoming connections across workers.

How It Works

The server uses a smart dual-transport architecture with protocol detection:

TCP Server (HTTP/1.1 and HTTP/2)

ASGIRI supports multiple methods for HTTP/2 negotiation:

1. ALPN (Application-Layer Protocol Negotiation): The standard TLS extension for HTTP/2 negotiation

   • During TLS handshake, client and server negotiate protocol (h2 for HTTP/2, http/1.1 for HTTP/1.1)
   • Recommended for production use with HTTPS
   • Automatically enabled when TLS certificates are provided

2. HTTP/2 Prior Knowledge: Direct HTTP/2 connection without negotiation

   • Client sends HTTP/2 connection preface (PRI * HTTP/2.0...)
   • Useful for testing and HTTP/2-only environments
   • Test with: curl --http2-prior-knowledge http://localhost:8000/

3. HTTP/1.1 Upgrade: Upgrades from HTTP/1.1 to HTTP/2 mid-connection

   • Client sends Upgrade: h2c header (h2c = HTTP/2 cleartext)
   • Fallback method for non-TLS scenarios

4. HTTP/1.1 Fallback: Falls back to HTTP/1.1 for standard HTTP requests

5. Advertisement: Automatically adds Alt-Svc headers to advertise HTTP/2 and HTTP/3 capability

UDP Server (HTTP/3)

1. QUIC Protocol: Handles HTTP/3 over QUIC (UDP-based transport)
2. TLS Integration: Built-in TLS 1.3 encryption (mandatory for HTTP/3)
3. Multiplexing: True stream independence without head-of-line blocking

For more details, see:

• Protocol Switching Guide
• HTTP/3 Implementation

Testing

# Test HTTP/1.1
curl -v http://localhost:8000/

# Test HTTP/2 (with prior knowledge)
curl --http2-prior-knowledge http://localhost:8000/

# Test HTTP/3 (requires curl with HTTP/3 support)
curl --http3 https://localhost:8443/ -k

Documentation

Want to learn more? Browse our documentation:

• CLI Guide — Command-line interface options and examples
• Protocol Switching — Deep dive into HTTP/2 negotiation and auto-detection
• HTTP/3 Implementation — Complete guide to HTTP/3 support and configuration
• Architecture — Internal design and implementation details
• WebSocket Implementation — WebSocket protocol support and usage

License

MIT