Update get_metadata_value to use v1 metadata server url for instance with fallback to project.

1 files changed, 36 insertions, 9 deletions

diff --git a/google-startup-scripts/usr/share/google/get_metadata_value b/google-startup-scripts/usr/share/google/get_metadata_value
index 005b44d..4df6186 100755
--- a/google-startup-scripts/usr/share/google/get_metadata_value
+++ b/google-startup-scripts/usr/share/google/get_metadata_value
@@ -16,20 +16,47 @@
 # Get a metadata value from the metadata server.
 
 declare -r VARNAME=$1
-declare -r MDS=http://169.254.169.254/computeMetadata/v1/instance/attributes
+declare -r MDS_PREFIX=http://169.254.169.254/computeMetadata/v1
+declare -r MDS_INSTANCE=${MDS_PREFIX}/instance/attributes
+declare -r MDS_PROJECT=${MDS_PREFIX}/project/attributes
 declare -r MDS_TRIES=${MDS_TRIES:-100}
 
+function metadata_get_url_code() {
+  return $(curl "${1}" -H "Metadata-Flavor: Google" -s \
+      -w "%{http_code}" -o /dev/null)
+}
+
+function print_metadata_value() {
+  local readonly response=$(curl "${1}" -H "Metadata-Flavor: Google" -s)
+  local readonly return_code=$?
+  # If the command completed successfully, print the metadata value to stdout.
+  if [[ ${return_code} == 0 ]]; then
+    printf ${response}
+  fi
+  return ${return_code}
+}
+
+function print_metadata_value_if_exists() {
+  local readonly url=$1
+  metadata_get_url_code ${url}
+  http_code=$?
+  # Test the instance metadata value.
+  if test ${http_code} -eq 200; then
+    print_metadata_value ${url}
+    return_code=$?
+  fi
+}
+
 function get_metadata_value() {
   local readonly varname=$1
-  local readonly tmpfile=$(mktemp)
-  curl -f ${MDS}/${varname} -H "Metadata-Flavor: Google" > ${tmpfile} 2>/dev/null
-  local return_code=$?
-  if [[ ${return_code} == 0 ]]; then
-    cat ${tmpfile}
-  else
-    echo "curl for ${varname} returned ${return_code}" > /dev/console
+  # Print the instance metadata value.
+  print_metadata_value_if_exists ${MDS_INSTANCE}/${varname}
+  return_code=$?
+  # If the instance doesn't have the value, try the project.
+  if [[ ${return_code} != 0 ]]; then
+    print_metadata_value_if_exists ${MDS_INSTANCE}/${varname}
+    return_code=$?
   fi
-  rm -f ${tmpfile}
   return ${return_code}
 }