Python WSGI & ASGI: Panduan Lengkap

📋 Daftar Isi

Pengenalan WSGI & ASGI
WSGI: Konsep Dasar
Membuat Aplikasi WSGI
Gunicorn: Production WSGI Server
ASGI: Konsep Dasar
Membuat Aplikasi ASGI
Uvicorn: ASGI Server
Starlette: Framework ASGI
Flask (WSGI) & Django (ASGI)
Deployment Production
Best Practices
Quiz Pemahaman

1. Pengenalan WSGI & ASGI

Ketika Anda menjalankan aplikasi web Python (Flask, Django, FastAPI), Anda memerlukan web server yang menerima HTTP request dari browser dan meneruskannya ke aplikasi Anda. WSGI dan ASGI adalah standar protokol yang mendefinisikan bagaimana web server berkomunikasi dengan aplikasi Python.

Apa Itu WSGI dan ASGI?

Aspek	WSGI	ASGI
Kepanjangan	Web Server Gateway Interface	Asynchronous Server Gateway Interface
PEP	PEP 3333	Proprietary (Django project)
Sync/Async	Synchronous	Asynchronous
WebSocket	❌ Tidak	✅ Ya
HTTP/2	Terbatas	✅ Ya
Framework	Flask, Django (legacy)	FastAPI, Starlette, Django 3.0+
Server	Gunicorn, uWSGI	Uvicorn, Daphne, Hypercorn

Diagram: WSGI vs ASGI Architecture

WSGI vs ASGI Architecture

2. WSGI: Konsep Dasar

WSGI (PEP 3333) adalah standar antarmuka antara web server dan aplikasi web Python. WSGI memastikan kompatibilitas antara berbagai server dan framework.

Bagaimana WSGI Bekerja

Aplikasi WSGI adalah sebuah callable (fungsi atau objek dengan __call__) yang menerima dua argumen:

environ — dictionary berisi informasi request (method, path, headers, dll)
start_response — callback untuk mengirim status dan headers

flowchart TB
    User["👤 User"] --> Nginx["🌐 Nginx\n(Reverse Proxy)"]
    Nginx -->|"Static files"| Static["📁 Static Files"]
    Nginx -->|"Dynamic"| App["🐍 Python App\n(Gunicorn/uvicorn)"]
    App --> DB["("#quot;🗄️ Database#quot;")"]
    App --> Cache["⚡ Redis Cache"]
    App --> Queue["📋 Task Queue\n(Celery)"]

    style User fill:#2a0f1e,stroke:#f472b6
    style Nginx fill:#2a1f0a,stroke:#f59e0b,stroke-width:2px
    style App fill:#0f2a1f,stroke:#3ecf8e,stroke-width:2px
    style DB fill:#0f1d3a,stroke:#60a5fa,stroke-width:1.5px
    style Cache fill:#1a0f2e,stroke:#a78bfa
    style Queue fill:#0a2a1f,stroke:#34d399

Nginx Reverse Proxy Config

Nginx — Reverse Proxy

# /etc/nginx/sites-available/myapp
server {
    listen 80;
    server_name myapp.example.com;
    
    # Redirect HTTP → HTTPS
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl;
    server_name myapp.example.com;
    
    ssl_certificate /etc/ssl/certs/myapp.crt;
    ssl_certificate_key /etc/ssl/private/myapp.key;
    
    # Static files (langsung serve oleh Nginx)
    location /static/ {
        alias /var/www/myapp/static/;
        expires 30d;
        add_header Cache-Control "public, immutable";
    }
    
    # Dynamic requests → Gunicorn/Uvicorn
    location / {
        proxy_pass http://127.0.0.1:8000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        # Timeouts
        proxy_connect_timeout 10s;
        proxy_read_timeout 30s;
        proxy_send_timeout 30s;
    }
    
    # WebSocket support (untuk ASGI)
    location /ws/ {
        proxy_pass http://127.0.0.1:8000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host;
    }
}

Systemd Service

Systemd — Service File

# /etc/systemd/system/myapp.service
[Unit]
Description=My Python Web Application
After=network.target

[Service]
User=www-data
Group=www-data
WorkingDirectory=/var/www/myapp
ExecStart=/var/www/myapp/venv/bin/gunicorn app:app -c gunicorn.conf.py
ExecReload=/bin/kill -s HUP $MAINPID
Restart=always
RestartSec=5
KillMode=mixed
TimeoutStopSec=10

[Install]
WantedBy=multi-user.target

11. Best Practices

💡 Tips Penting

Development → Gunakan uvicorn --reload atau flask run --debug
Production WSGI → Gunicorn dengan sync atau gthread workers
Production ASGI → Uvicorn dengan multiple workers atau Gunicorn + UvicornWorker
Selalu gunakan reverse proxy (Nginx/Caddy) di production
Workers formula → 2 × CPU cores + 1
Jangan gunakan development server Flask/Django untuk production