Add script for resizing GCE persistent disks

Resizes the persistent disk and then SSHs into the machine that has it
mounted and resizes the file system to take advantage of the new space.

Example usage:
MIRROR_DISK_SIZE=250GB ./resize_disks.sh ./configs/ct-mirror-aviator.sh

cloud/google/resize_disks.sh

@@ -0,0 +1,66 @@
+#!/bin/bash
+#
+# Pass a project config file to this command to have it resize all of that
+# project's disks to the size dictated by ./config.sh.
+set -e
+DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+if [ "$1" == "" ]; then
+  echo "Usage: $0 <config-file>"
+  exit 1
+fi
+CONFIG_FILE="$1"
+
+. ${DIR}/config.sh ${CONFIG_FILE}
+GCLOUD="gcloud --project ${PROJECT}"
+
+case "${INSTANCE_TYPE}" in
+  "mirror")
+    NUM_REPLICAS=(${MIRROR_NUM_REPLICAS[@]})
+    DISKS=(${MIRROR_DISKS[@]})
+    MACHINES=(${MIRROR_MACHINES[@]})
+    ZONES=(${MIRROR_ZONES[@]})
+    NEW_SIZE=(${MIRROR_DISK_SIZE[@]})
+    ;;
+  "log")
+    NUM_REPLICAS=(${LOG_NUM_REPLICAS[@]})
+    DISKS=(${LOG_DISKS[@]})
+    MACHINES=(${LOG_MACHINES[@]})
+    ZONES=(${LOG_ZONES[@]})
+    NEW_SIZE=(${LOG_DISK_SIZE[@]})
+   ;;
+  "etcd")
+    NUM_REPLICAS=(${ETCD_NUM_REPLICAS[@]})
+    DISKS=(${ETCD_DISKS[@]})
+    MACHINES=(${ETCD_MACHINES[@]})
+    ZONES=(${ETCD_ZONES[@]})
+    NEW_SIZE=(${ETCD_DISK_SIZE[@]})
+   ;;
+  "prometheus")
+    NUM_REPLICAS=(${PROMETHEUS_NUM_REPLICAS[@]})
+    DISKS=(${PROMETHEUS_DISKS[@]})
+    MACHINES=(${PROMETHEUS_MACHINES[@]})
+    ZONES=(${PROMETHEUS_ZONES[@]})
+    NEW_SIZE=(${PROMETHEUS_DISK_SIZE[@]})
+   ;;
+  *)
+    echo "Unknown INSTANCE_TYPE: ${INSTANCE_TYPE}"
+    exit 1
+esac
+
+for i in $(seq 0 $((${NUM_REPLICAS} - 1))); do
+  ZONE="${ZONES[${i}]}"
+  MACHINE="${MACHINES[${i}]}"
+  DISK="${DISKS[${i}]}"
+
+  echo "Resizing ${DISK} to ${NEW_SIZE}..."
+  if ! ${GCLOUD} compute disks resize "${DISK}" \
+    --zone "${ZONE}" \
+    --size "${NEW_SIZE}"; then
+    continue
+  fi
+
+  echo "Resizing file system on ${MACHINE}..."
+  ${GCLOUD} compute ssh "${MACHINE}" \
+    --zone "${ZONE}" \
+    --command 'sudo resize2fs "$(findmnt -n -o SOURCE --target /data)"'
+done