deploy: Check correct usage of --upgrade for rawdisk deployments

This avoids confusion when the user expected to be doing an initial
deployment and wasn't aware that a file with the same name as the
target already existed. Previously rawdisk.write would try to mount
the file and upgrade it.

Now we require the user to pass '--upgrade' when they intend to
upgrade, as with other deployment extensions.

1 files changed, 21 insertions, 0 deletions

diff --git a/rawdisk.check b/rawdisk.check
index 6a656ee7..5e75abe2 100755
--- a/rawdisk.check
+++ b/rawdisk.check
@@ -20,6 +20,8 @@ import cliapp
 
 import morphlib.writeexts
 
+import os
+
 
 class RawdiskCheckExtension(morphlib.writeexts.WriteExtension):
     def process_args(self, args):
@@ -28,4 +30,23 @@ class RawdiskCheckExtension(morphlib.writeexts.WriteExtension):
 
         self.require_btrfs_in_deployment_host_kernel()
 
+        location = args[0]
+        upgrade = self.get_environment_boolean('UPGRADE')
+        if upgrade:
+            if not os.path.isfile(location):
+                raise cliapp.AppException(
+                    'Cannot upgrade %s: it is not an existing disk image' %
+                    location)
+
+            version_label = os.environ.get('VERSION_LABEL')
+            if version_label is None:
+                raise cliapp.AppException(
+                    'VERSION_LABEL was not given. It is required when '
+                    'upgrading an existing system.')
+        else:
+            if os.path.exists(location):
+                raise cliapp.AppException(
+                    'Target %s already exists. Pass --upgrade if you want to '
+                    'update an existing image.' % location)
+
 RawdiskCheckExtension().run()