Fixes NixOS/nixops#756.

AmineChikhaoui · rbvermaa · commit ef5a4295b422 · 2018-01-18T13:18:07.000+01:00
Seems the google compute metadata service behavior changed a bit recently which caused this issue ? see: https://cloud.google.com/compute/docs/storing-retrieving-metadata (cherry picked from commit 5dba59d)
diff --git a/nixos/modules/virtualisation/google-compute-image.nix b/nixos/modules/virtualisation/google-compute-image.nix
@@ -211,7 +211,7 @@ in
           echo "Obtaining SSH keys..."
           mkdir -m 0700 -p /root/.ssh
           AUTH_KEYS=$(${mktemp})
-          ${wget} -O $AUTH_KEYS http://metadata.google.internal/computeMetadata/v1/project/attributes/sshKeys
+          ${wget} -O $AUTH_KEYS --header="Metadata-Flavor: Google" http://metadata.google.internal/computeMetadata/v1/instance/attributes/sshKeys
           if [ -s $AUTH_KEYS ]; then
 
             # Read in key one by one, split in case Google decided
