gcssh

#!/bin/bash

CACHE_FILE=~/.gssh-zone-cache

if [ $# -lt 1 -o "$1" = "-h" -o "$1" = "--help" ]
then
	echo "Usage:"
	echo "$0 --get-zone hostname    : Get the zone for a host"
	echo "$0 --flush-cache          : Flush all hosts from the zone cache"
	echo "$0 --flush-cache hostname : Flush a specific host from the zone cache"
	echo "$0 hostname [gcloud arguments...]"
	echo
	exit 1
fi

if [ "$1" = "--flush-cache" ]
then
	if [ $# -eq 1 ]
	then
		rm -f "$CACHE_FILE"
	else
		# BSD sed needs the -E argument but GNU sed does not
		if [ `uname` = "Darwin" ]
		then
			sed -E -i.bak "/^$2:/d" "$CACHE_FILE"
		else
			sed -i.bak "/^$2:/d" "$CACHE_FILE"
		fi
	fi
	exit 0
fi

GETZONE=0
if [ "$1" = "--get-zone" ]
then
	GETZONE=1
	shift
fi

# Check for the zone in the cache
GCEHOST="$1"
shift

if [ -f "$CACHE_FILE" ]
then
	ZONE=`grep "^$GCEHOST:" "$CACHE_FILE" | sed 's/^[^:]*:\(.*\)$/\1/'`
	if [ "$ZONE" != "" ]
	then
		echo "Using zone $ZONE (from cache)" >&2
	fi
else
	ZONE=""
fi

if [ "$ZONE" = "" ]
then
	# Get the zone from gcloud and store it in the cache
	echo "Detecting zone for $GCEHOST..." >&2
	ZONE=`gcloud compute instances list --filter="name=('$GCEHOST')" | grep "$GCEHOST" | awk '{print $2}'`
	if [ "$ZONE" = "" ]
	then
		echo "ERROR: Could not detect the zone for $GCEHOST" >&2
		exit 1
	fi
	
	echo "Zone detected as $ZONE" >&2
	echo "$GCEHOST:$ZONE" >>"$CACHE_FILE"
fi

if [ $GETZONE -eq 1 ]
then
	echo $ZONE
else
	gcloud compute ssh $GCEHOST --ssh-flag="-A" --zone $ZONE $@
fi