The cluster name in generate-yaml.sh is now a random string. (#370)

This change removes the static name from generate-yaml.sh and instead
generates a random string for the name. The reason for doing this is to
allow the script to be run over and over without failing due to accounts
already existing with the same name and to allow developers to verify
their changes with a more clean environment

clusterctl/examples/google/generate-yaml.sh

@@ -21,7 +21,13 @@ set -o pipefail
 GCLOUD_PROJECT=$(gcloud config get-value project)
 ZONE=$(gcloud config get-value compute/zone)
 ZONE="${ZONE:-us-central1-f}"
-CLUSTER_NAME=test1
+# Generate a somewhat unique cluster name, UUID is not an option as service-accounts are limited to 30 characters in length
+# and one has a 19 character prefix (i.e. 'machine-controller-'). Of the 11 remaining characters 6 are reserved for the human
+# friendly cluster name, one for a dash, and 5 are left for this random string.
+RANDOM_STRING=$(head -c5 < <(LC_ALL=C tr -dc 'a-zA-Z0-9' < /dev/urandom) | tr '[:upper:]' '[:lower:]')
+# Human friendly cluster name, limited to 6 characters
+HUMAN_FRIENDLY_CLUSTER_NAME=test1
+CLUSTER_NAME=${HUMAN_FRIENDLY_CLUSTER_NAME}-${RANDOM_STRING}
 
 OUTPUT_DIR=out
 
@@ -179,3 +185,5 @@ cat $ADDON_TEMPLATE_FILE \
   | sed -e "s/\$CLUSTER_NAME/$CLUSTER_NAME/" \
   | sed "s/\$LOADBALANCER_SA_KEY/$LOADBALANCER_SA_KEY/" \
   > $ADDON_GENERATED_FILE
+
+echo -e "\nYour cluster name is '${CLUSTER_NAME}'"