zig-http-proxy-docker

Small Zig HTTPS forward proxy for Bun fetch() running in Docker.

Scope

• Supports HTTPS targets via HTTP CONNECT
• Requires Proxy-Authorization: Basic ...
• Exposes a plain HTTP proxy endpoint such as http://user:password@127.0.0.1:8080
• Intentionally does not support plain HTTP target URLs in v1

Build

docker build -t zig-http-proxy .

Run

docker run --rm \
  -p 8080:8080 \
  -e PROXY_USERNAME=user \
  -e PROXY_PASSWORD=password \
  zig-http-proxy

Optional environment variables:

• PROXY_BIND_HOST default 0.0.0.0
• PROXY_PORT default 8080
• PROXY_CONNECT_TIMEOUT_MS default 10000
• PROXY_IO_BUFFER_SIZE default 16384
• PROXY_MAX_HEADER_BYTES default 32768

Bun example

const res = await fetch("https://foobar.com", {
  proxy: "http://user:password@127.0.0.1:8080",
});

console.log(res.status);

Verify with curl

Successful HTTPS request through the proxy:

curl -x http://user:password@127.0.0.1:8080 https://example.com -I

Expected authentication failure:

curl -x http://127.0.0.1:8080 https://example.com -I

Expected unsupported plain HTTP target:

curl -x http://user:password@127.0.0.1:8080 http://example.com -I