Modify euca test to get zone using describe

This modifies the euca test to include describe-availability-zones
so that it is covered. This allows us to not need to hard-code a
zone name for the volume tests.

Change-Id: Iaae0589d4338d948981ca6e2229d2ceb73ff38ef
diff --git a/exercises/euca.sh b/exercises/euca.sh
index fd11622..58b5d91 100755
--- a/exercises/euca.sh
+++ b/exercises/euca.sh
@@ -24,7 +24,6 @@
 # Keep track of the current directory
 EXERCISE_DIR=$(cd $(dirname "$0") && pwd)
 TOP_DIR=$(cd $EXERCISE_DIR/..; pwd)
-VOLUME_ZONE=nova
 VOLUME_SIZE=1
 ATTACH_DEVICE=/dev/vdc
 
@@ -75,11 +74,15 @@
 # Volumes
 # -------
 if [[ "$ENABLED_SERVICES" =~ "n-vol" || "$ENABLED_SERVICES" =~ "c-vol" ]]; then
+   VOLUME_ZONE=`euca-describe-availability-zones | head -n1 | cut -f2`
+   die_if_not_set VOLUME_ZONE "Failure to find zone for volume"
+
    VOLUME=`euca-create-volume -s 1 -z $VOLUME_ZONE | cut -f2`
    die_if_not_set VOLUME "Failure to create volume"
 
    # Test that volume has been created
    VOLUME=`euca-describe-volumes | cut -f2`
+   die_if_not_set VOLUME "Failure to get volume"
 
    # Test volume has become available
    if ! timeout $ASSOCIATE_TIMEOUT sh -c "while ! euca-describe-volumes $VOLUME | grep -q available; do sleep 1; done"; then