http-reverse-proxy.ae

// Reverse-proxy demo — std.http.proxy.
//
// Forwards every request to a single upstream HTTP server. The
// proxy strips Hop-by-Hop headers, adds X-Forwarded-{For,Proto,
// Host} + Via, rewrites Host: to the upstream's host, and returns
// the upstream's response verbatim (status, headers, body).
//
// Run two processes:
//
//     # 1) Start an upstream (any HTTP server). For demo purposes
//     # we use python3's stdlib server:
//     python3 -m http.server 9000 --directory /tmp
//
//     # 2) Build + run this example:
//     ae build examples/stdlib/http-reverse-proxy.ae -o /tmp/proxy
//     /tmp/proxy
//
//     # 3) Test:
//     curl http://localhost:8080/                       # served by python
//     curl -H 'X-Forwarded-For: 1.2.3.4' http://localhost:8080/
//     # → upstream sees X-Forwarded-For: 1.2.3.4, <client_ip>
//
// For the production pool shape (load balancing, health checks,
// cache, circuit breaker), see docs/http-reverse-proxy.md.

import std.http
import std.http.proxy

const PORT = 8080

main() {
    server = http.server_create(PORT)
    if server == 0 {
        println("server_create failed")
        return
    }
    // Loopback only, which is what the URLs above reach. The default host
    // is every interface: pass "0.0.0.0" here to serve the network. The
    // example sweep runs this, and on Windows each new executable that
    // listens on every interface opens a firewall prompt (#2639).
    http.server_set_host(server, "127.0.0.1")

    // Keep-alive so curl --http1.1 can reuse the TCP connection
    // across multiple proxied requests.
    ka_err = http.server_set_keepalive(server, 1, 0, 30000ms)
    if ka_err != "" {
        println("keepalive: ${ka_err}")
        return
    }

    // Single upstream, RR (no other to balance against), 30s
    // request timeout, default opts (XFF + XFP + XFH on; Host
    // rewritten to upstream; 8 MiB body cap).
    proxy_err = proxy.mount_simple(server, "/", "http://localhost:9000", 30)
    if proxy_err != "" {
        println("mount_simple: ${proxy_err}")
        return
    }

    println("listening on http://localhost:${PORT}/ (forwarding to localhost:9000)")
    err = http.server_start(server)
    if err != "" {
        println("server_start: ${err}")
    }
}