A cross-platform test server with support for HTTP/1.1 connection upgrades and deterministic scripted responses.

Multi-platform Docker images are available at gesellix/echo-server:<version> with <version> matching Git tags/releases on GitHub.

Supported platforms:

• linux/amd64
• linux/arm64/v8
• windows-ltsc2022

• HTTP/1.1 Upgrade Handling to raw TCP
• Scripted deterministic responses via JSON body
• Interactive commands in default mode (e.g. reset, set 10)
• Cross-platform & container-friendly
• Useful for client protocol testing and upgrade simulations

POST /api/stream HTTP/1.1
Connection: Upgrade
Upgrade: testproto

The server upgrades the connection and speaks raw TCP after switching protocols.

When no script is provided, the server enters a simple interactive loop:

• Sends a counter every second:

  [0] scripted: counter: 0
  [1] scripted: counter: 1
  ...
  

• Accepts basic commands from the client:

  • reset → resets counter
  • set <n> → sets counter to <n>
  • any other input → "unknown command"

You can connect using the built-in client or tools like nc:

go run ./src/hijack_client.go
# or
{ echo -en "GET /api/stream HTTP/1.1\r\nHost: localhost\r\nConnection: Upgrade\r\nUpgrade: testproto\r\n\r\n"; cat; } | nc localhost 8080

Send a JSON payload with a POST request to /api/stream, along with Upgrade headers.

POST /api/stream HTTP/1.1
Host: localhost:8080
Connection: Upgrade
Upgrade: testproto
Content-Type: application/json

{
  "actions": [
    { "type": "response", "text": "first" },
    { "type": "delay",    "ms": 1000 },
    { "type": "response", "text": "second" },
    { "type": "close" }
  ]
}

A simple Go client for interactive testing is available at:

./src/hijack_client.go

It connects to the server, performs the upgrade handshake, and allows typing commands live.

To run via Docker:

docker run --rm -it -p 8080:8080 gesellix/echo-server:<version>

Issues and contributions welcome via GitHub.