upstream phoenix_backend {
    # Hash based on WebSocket handshake key for sticky sessions
    # Note: Each new connection gets a new key, so reconnections may route differently
    hash $http_sec_websocket_key consistent;
    
    # Failover configuration: mark server as down after 3 failed attempts within 30s
    # Server will be retried after 30s
    server phoenix1:4000 max_fails=1 fail_timeout=30s;
    server phoenix2:4000 max_fails=1 fail_timeout=30s;
    server phoenix3:4000 max_fails=1 fail_timeout=30s;
}

server {
    listen 80;
    server_name localhost;

    location /socket {
        proxy_pass http://phoenix_backend;
        proxy_http_version 1.1;
        
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        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;
    }

    location /api {
        proxy_pass http://phoenix_backend;
        proxy_http_version 1.1;
        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;
    }

    location /health {
        access_log off;
        return 200 "healthy\n";
        add_header Content-Type text/plain;
    }
}