multisocat

A socat image that runs on multiple ports.

Design

As nobody but can be overriden by user option.

For each environment variable that starts with SOCAT_ spawn off an instance of SOCAT_ with those parameters. Note that order is not guaranteed.

Have nc installed to allow creation of HEALTHCHECK. (A good addition to this image is a small shell script that will just do nc -z given a list of ports locally and verify that they are all open, maybe in a future release or PR)

Additionally provide BLACKHOLE_TCP and BLACKHOLE_UDP which provides a comma separated list of ports to listen but not respond to. Primarily used for testing. These would be implemented as nc -l and nc -ul respectively.

Wait for all those socat instances to finish.

Example

Here is an example of a service that forwards to a remote logstash/graylog server that exposes several ports.

version: '3.7'
services:
  log:
    image: trajano/multisocat
    user: root
    environment:
      SOCAT_BEATS: "TCP-LISTEN:5044,fork TCP:202.54.1.5:5044"
      SOCAT_TEXT: "TCP-LISTEN:5555,fork TCP:202.54.1.5:5555"
      SOCAT_GELF: "UDP-LISTEN:12201,fork UDP:202.54.1.5:12201"
      BLACKHOLE_TCP: "514,50000"
      BLACKHOLE_UDP: "514,60000"
    healthcheck:
      test: nc -z localhost 5044

Note that the user needs to be root in order for ports less than 1024 to be openned.