decompressor

decompressor is a small reverse proxy that sits in front of upstream services or intermediate proxies that do not correctly support compressed HTTP request bodies.

Its main job is to normalize incoming request bodies before they reach the next hop:

• if the incoming request body uses Content-Encoding: gzip, decompressor will stream-decompress it before forwarding upstream
• if the incoming request body is not compressed, decompressor forwards it as-is
• upstream responses are streamed back to the client unchanged

What This Replaces

If your original docker-compose.yml looked like this:

services:
  upstream-service:
    image: your/upstream-image:latest
    container_name: upstream-service
    restart: unless-stopped
    ports:
      - "127.0.0.1:5505:8080"

then the host port 5505 was pointing directly to the upstream service.

With this project, decompressor takes over that public port, and the upstream service stays internal.

Recommended Compose Setup

Use this project directory as the compose root and run:

services:
  upstream-service:
    image: your/upstream-image:latest
    container_name: upstream-service
    restart: unless-stopped
    expose:
      - "8080"

  decompressor:
    image: ghcr.io/550w-host/decompressor:latest
    container_name: decompressor
    restart: unless-stopped
    depends_on:
      - upstream-service
    environment:
      DECOMPRESSOR_LISTEN_ADDR: 0.0.0.0:5505
      DECOMPRESSOR_UPSTREAM_URL: http://upstream-service:8080
    ports:
      - "127.0.0.1:5505:5505"

That same setup is also included in docker-compose.yml.

Getting The Repo

git clone https://github.com/550W-HOST/decompressor.git
cd decompressor

How It Works

Client traffic now flows like this:

client -> localhost:5505 -> decompressor -> upstream-service:8080

Request handling rules:

• Content-Encoding: gzip: streamed through a gzip decoder, then forwarded upstream without the Content-Encoding header
• no request compression: forwarded directly
• the original Host header is preserved when forwarding to the upstream
• X-Forwarded-For, X-Forwarded-Proto, and X-Forwarded-Host are attached for the upstream
• responses: streamed straight back to the client

Environment Variables

decompressor reads its runtime settings from environment variables.

In Docker Compose, the service definition passes the DECOMPRESSOR_* values directly with environment:. In local development and the external CPA tests, the easiest way is to keep values in .env.

Example:

TEST_API_BASE=https://your-api.example.com
TEST_API_KEY=your_api_key_here
TEST_MODEL=gpt-5.2
DECOMPRESSOR_LISTEN_ADDR=0.0.0.0:5505
DECOMPRESSOR_UPSTREAM_URL=http://upstream-service:8080

The sample values are also present in .env.example.

Build And Run

Start everything:

docker compose up -d

Once it is running, point your client at:

http://127.0.0.1:5505

Local Development

Run the Rust service directly:

cargo run

By default it listens on 0.0.0.0:5505 and forwards to http://127.0.0.1:8080.

Before starting it locally, create .env from .env.example.

Run tests:

cargo test

The gzip compatibility investigation tests live in tests/cpa_gzip_request_body.rs. The local proxy end-to-end tests live in tests/proxy_forwarding.rs.