rlisthosts

#!/usr/bin/env bash
# rlisthosts -- helper for rdo/rup to discover hosts
#
# Might use LDAP one day, but for now it"s just a static list (instead of
# having that list hardcoded in rup, then copied to other tools).

. lib.bash || exit

usage() {
	echo "Usage: ${0##*/} [+]<host|@group>..."
	echo
	echo "Produce a list of hostnames, expanding '@group' specifications."
	echo "Comma-separated items are accepted and expanded to space-separated."
	echo
	echo_opt "host, @grp"	"add single host or the specified group"
	echo_opt "+host, +@grp"	"append to default list, instead of replacing"
	echo_opt "-a"		"add all hosts from all groups"
	echo_opt "-l"		"list known groups and exit"
}

declare -A groups=()

groups[default]="wolke sky star land ember wind dust"

if [[ -e ~/.config/rlisthosts ]]; then
	while read -r alias rest; do
		if [[ $alias == [!#]* ]]; then
			groups[$alias]=$rest
		fi
	done < ~/.config/rlisthosts
fi

hosts=

set -f
set -- ${*//,/ }
set +f

(( $# )) || set -- @default

for arg; do
	if [[ $arg == +* ]]; then
		arg=${arg#+}
		hosts=${groups[default]}
	fi
	case $arg in
		--help)
			usage; exit 0;;
		-a)
			hosts+=" ${groups[*]}";;
		-l)
			for group in "${!groups[@]}"; do
				echo "$group = ${groups[$group]}"
			done; exit 0;;
		-*)
			vmsg "Unknown option '$arg'" >&2; exit 2;;
		@all)
			hosts+=" ${groups[*]}";;
		@*)
			if [[ ! ${groups[${arg#@}]} ]]; then
				vmsg "Unknown group '$arg'" >&2; exit 1
			fi
			hosts+=" ${groups[${arg#@}]}";;
		*)
			hosts+=" $arg";;
	esac
done

set -f
hosts=${hosts//,/ }

declare -A seen=()
for host in $hosts; do
	seen[$host]=1
done

echo ${!seen[@]}
set +f