varnish-configuration-loader

#! /bin/sh

print_usage()
{
	cat << EOF 1>&2
Usage:
	$(basename "$0") [ -n <varnish-instance-name> ] -I <varnish-cli-command-file> [ -i <reload-interval> ]
EOF
}

getopt_output="$(getopt --name "$(basename $0)" --options "h,n:,I:,i:" -- "$@")"

if [ $? -ne 0 ]
then
	printf "\n"
	print_usage
	exit 1
fi

eval set -- "${getopt_output}"

while true
do
	case "$1"
	in
		"-h")
			print_usage
			exit 0
		;;
		"-n")
			varnish_name="$2"
			shift 2
		;;
		"-I")
			cli_file="$(realpath --no-symlinks "$2")"
			shift 2
		;;
		"-i")
			interval="$2"
			shift 2
		;;
		"--")
			break
		;;
	esac
done

argument_error=false

if [ -z "${cli_file}" ]
then
	printf -- "-I option is missing\n"
	argument_error=true
fi

if ${argument_error}
then
	printf "\n"
	print_usage
	exit 1
fi

if [ ! -f "${cli_file}" ]
then
	printf "Varnish CLI command file ('%s') not found\n" "${cli_file}"
	exit 1
fi

varnishadm_options=""

if [ -n "${varnish_name}" ]
then
	varnishadm_options="${varnishadm_options} -n \"${varnish_name}\""
fi

_varnishadm() {
	eval varnishadm ${varnishadm_options} "$@"
}

ping() {
	until _varnishadm ${varnishadm_options} ping > /dev/null 2>&1
	do
		sleep 1
	done
}

load_configuration() {
	printf "Loading Varnish configuration\n"
	while read "command"
	do
		if ! _varnishadm ${varnishadm_options} ${command}
		then
			printf "Failed loading Varnish configuration\n"
			return 1
		fi
	done < "${cli_file}"
	printf "Successfully loaded Varnish configuration\n"

	if [ "$(_varnishadm ${varnishadm_options} status -j | jq -er ".[3]")" = "stopped" ]
	then
		printf "Starting Varnish\n"
		if ! _varnishadm ${varnishadm_options} start
		then
			printf "Failed starting Varnish\n"
			return 1
		fi
		printf "Successfully started Varnish\n"
	fi

	return 0
}

clean_configuration() {
	if ! unused_labels="$(_varnishadm ${varnishadm_options} vcl.list -j | jq -er ".[3:] | map(select(.status == \"available\" and .state == \"label\" and .label.refs == null))")"
	then
		printf "Failed to retrieve unused Varnish configuration labels\n"
		return 1
	fi

	for i in $(seq 0 $(echo "${unused_labels}" | jq "length - 1"))
	do
		label="$(echo "${unused_labels}" | jq -r ".[$i].name")"
		printf "Discarding unused Varnish configuration label '${label}'\n"
		_varnishadm ${varnishadm_options} vcl.discard "${label}"
		printf "Successfully discarded unused Varnish configuration label\n"
	done

	if ! unused_files="$(_varnishadm ${varnishadm_options} vcl.list -j | jq -er ".[3:] | map(select(.status == \"available\" and .state != \"label\" and .labels == null))")"
	then
		printf "Failed to retrieve unused Varnish configuration files\n"
		return 1
	fi

	for i in $(seq 0 $(echo "${unused_files}" | jq "length - 1"))
	do
		file="$(echo "${unused_files}" | jq -r ".[$i].name")"
		printf "Discarding unused Varnish configuration file '${file}'\n"
		_varnishadm ${varnishadm_options} vcl.discard "${file}"
		printf "Successfully discarded unused Varnish configuration file\n"
	done

	return 0
}

printf "Waiting for Varnish to respond to ping\n"
ping
printf "Varnish successfully responded to ping\n"

if [ -z "${interval}" ]
then
	load_configuration
else
	old_checksum=""

	while true
	do
		checksum="$(sha256sum "${cli_file}")"

		ping

		if [ "${checksum}" != "${old_checksum}" ]
		then
			load_configuration
			old_checksum="${checksum}"
		fi

		clean_configuration

		sleep "${interval}"
	done
fi