docker-port-forward

#!/bin/bash

# If it's stupid but it works, it isn't stupid.

cleanup() {
	if [[ ! -z "$socatPid" ]]; then
		kill "$socatPid"
		wait "$socatPid"
	fi
}

trap cleanup EXIT

if [[ -z "$1" ]]; then
	echo "$0 container sourcePort:destinationPort [command [options...]]"
	echo ""
	echo "Forward port from sourcePort on localhost to destinationPort located inside a given container."
	echo "Optionally a command might be provided which will be called when tunnel is open. The tunel will be closed"
	echo "when command finishes"
	exit 1
fi

set -e

if [[ "$1" == "--internal" ]]; then
	internal="true"
	shift
fi

container="$1"
ports="$2"

shift
shift

sourcePort="$(echo -n "$ports" | cut -d':' -f1)"
destinationPort="$(echo -n "$ports" | cut -d':' -f2)"


if [[ "$internal" == "true" ]]; then
	docker run --rm -i --log-driver=none "--net=container:$container" alpine/socat STDIO "TCP4:localhost:$destinationPort"
else
	socat TCP4-LISTEN:$sourcePort,reuseaddr,fork SYSTEM:"$0 --internal $container $destinationPort" &
	socatPid="$!"

	if [[ -z "$1" ]]; then
		sleep infinity
	else
		"$@"
		sleep 1 # wait for forked Docker container to finish to prevent socat error
	fi

fi