Add HTTP/Streamable HTTP transport for containerised deployment

[eejd]

Summary

This project already does the hard part — Docker SDK integration via the Unix socket. The missing piece is an HTTP transport mode so it can be deployed as a standalone container accessible at http://localhost:<port>/mcp rather than requiring a stdio subprocess on the host.

Use case

Many agent orchestration setups (multi-agent systems, Claude Code MCP configs, etc.) prefer HTTP MCP servers they can declare once in a config file and share across sessions, rather than relying on claude_desktop_config.json subprocess launchers.

A containerised deployment pattern:

services:
  docker-mcp:
    image: docker-mcp:latest
    ports:
      - "127.0.0.1:4001:8080"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    environment:
      DOCKER_MCP_TRANSPORT: http
      DOCKER_MCP_PORT: 8080

With a corresponding MCP client config:

{ "docker-mcp": { "type": "http", "url": "http://localhost:4001/mcp" } }

This is especially useful for homelab / self-hosted setups where multiple agents share a common pool of MCP services, all declared in a single config rather than per-client subprocess entries.

Proposed change

I'd like to contribute a PR that:

1. Adds --transport http mode using FastMCP's built-in HTTP support (run_streamable_http_async)
2. Adds a Dockerfile that installs the package, exposes port 8080, mounts /var/run/docker.sock as a volume, and defaults to HTTP transport
3. Adds a docker-compose.example.yml in docs/

The change would be backward-compatible — stdio remains the default, HTTP is opt-in via env var or CLI flag.

Questions for maintainer

• Is HTTP transport in scope for this project?
• Any preference on FastMCP vs raw mcp server primitives for the transport layer?
• Would you accept a PR that adds this as an optional mode (stdio remains default)?

Happy to open a draft PR once there's alignment on direction.