#!/bin/bash

usage() {

	echo "$0 [-f FLANNEL-ENV-FILE] [-d DOCKER-ENV-FILE] [-i] [-c] [-m]

Generate Docker daemon options based on flannel env file

OPTIONS:

	-f	Path to flannel env file. Defaults to /run/flannel/subnet.env

	-d	Path to Docker env file to write to. Defaults to /run/docker_opts.env

	-i	Output each Docker option as individual var. e.g. DOCKER_OPT_MTU=1500

	-c	Output combined Docker options into DOCKER_OPTS var

	-k	Set the combined options key to this value (default DOCKER_OPTS=)

	-m	Do not output --ip-masq (useful for older Docker version)

" >/dev/stderr 

	exit 1

}

flannel_env="/run/flannel/subnet.env"

docker_env="/run/docker_opts.env"

combined_opts_key="DOCKER_OPTS"

indiv_opts=false

combined_opts=false

ipmasq=true

while getopts "f:d:ick:" opt; do

	case $opt in

		f)

			flannel_env=$OPTARG

			;;

		d)

			docker_env=$OPTARG

			;;

		i)

			indiv_opts=true

			;;

		c)

			combined_opts=true

			;;

		m)

			ipmasq=false

			;;

		k)

			combined_opts_key=$OPTARG

			;;

		\?)

			usage

			;;

	esac

done

if [ $indiv_opts = false ] && [ $combined_opts = false ]; then

	indiv_opts=true

	combined_opts=true

fi

if [ -f "$flannel_env" ]; then

	source $flannel_env

fi

if [ -n "$FLANNEL_SUBNET" ]; then

	DOCKER_OPT_BIP="--bip=$FLANNEL_SUBNET"

fi

if [ -n "$FLANNEL_MTU" ]; then

	DOCKER_OPT_MTU="--mtu=$FLANNEL_MTU"

fi

if [ "$FLANNEL_IPMASQ" = true ] && [ $ipmasq = true ] ; then

	DOCKER_OPT_IPMASQ="--ip-masq=false"

fi

eval docker_opts="\$${combined_opts_key}"

docker_opts+=" "

echo -n "" >$docker_env

for opt in $(compgen -v DOCKER_OPT_); do

	eval val=\$$opt

	if [ "$indiv_opts" = true ]; then

		echo "$opt=\"$val\"" >>$docker_env

	fi

	docker_opts+="$val "

done

if [ "$combined_opts" = true ]; then

	echo "${combined_opts_key}=\"${docker_opts}\"" >>$docker_env

fi