Sablier TCP Proxy

A simple TCP proxy that connects to Sablier on each incoming connection. The backend will be started and stopped according to the Sablier configuration.

Every time a new client connect, the Sablier blocking endpoint is called. As long as there is at least one active connection, a background task pings the Sablier endpoint to prevent the services from shutting down if there are only long running connections.

Since this proxy is not protocol aware and not limited to HTTP, the dynamic Sablier configuration doesn't make sense. Therefore only the blocking configuration is implemented.

Usage and Configuration

Replace your Caddy, Traefik or Nginx reverse proxy with ghcr.io/vbrandl/sablier-proxy and configure the proxy service.

The proxy is configured using environment variables and matches the Sablier configuration for other reverse proxies.

Variable	Default Value	Description
LISTEN		IP and port to listen on
UPSTREAM		Upstream IP and port
SABLIER_URL	http://sablier:10000	URL of the Sablier service.
NAMES
GROUP
SESSION_DURATION		Duration until the backend will be shut down
BLOCKING_TIMEOUT
PING_INTERVAL_SEC	10	Interval in which the Sablier endpoint is pinged if there is at least one active connection
UPSTREAM_RETRIES	5	When the backend gets started, this number controls how often the Sablier endpoint is checked before the connection will be dropped
UPSTREAM_RETRY_DURATION_MS	200	Duration between UPSTREAM_RETRIES in ms

Example

The following example will shut down the echo service after 10 seconds of inactivity

services:
  proxy:
    image: ghcr.io/vbrandl/sablier-proxy:latest
    ports:
      - '8080:8080'
    environment:
      - LISTEN="0.0.0.0:8080"
      - UPSTREAM="echo:80"
      - GROUP="demo"
      # shutdown echo server after 10s
      - SESSION_DURATION="10s"
      # block 2s when waiting for the echo server to start
      - BLOCKING_TIMEOUT="2s"

  echo:
    image: cjimti/go-echo
    environment:
      - TCP_PORT=80
    labels:
      - sablier.enable=true
      - sablier.group=demo

  sablier:
    image: acouvreur/sablier:1.7.0
    command:
        - start
        - --provider.name=docker
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock'

License

sablier-proxy is licensed under the MIT License (LICENSE or http://opensource.org/licenses/MIT).