Check file can be created at location

1 files changed, 22 insertions, 1 deletions

diff --git a/morphlib/exts/kvm.check b/morphlib/exts/kvm.check
index 1bb4007a..3c6accbf 100755
--- a/morphlib/exts/kvm.check
+++ b/morphlib/exts/kvm.check
@@ -1,5 +1,5 @@
 #!/usr/bin/python
-# Copyright (C) 2014  Codethink Limited
+# Copyright (C) 2014-2015 Codethink Limited
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -43,6 +43,7 @@ class KvmPlusSshCheckExtension(morphlib.writeexts.WriteExtension):
         ssh_host, vm_name, vm_path = self.check_and_parse_location(location)
 
         self.check_ssh_connectivity(ssh_host)
+        self.check_can_create_file_at_given_path(ssh_host, vm_path)
         self.check_no_existing_libvirt_vm(ssh_host, vm_name)
         self.check_extra_disks_exist(ssh_host, self.parse_attach_disks())
 
@@ -73,6 +74,26 @@ class KvmPlusSshCheckExtension(morphlib.writeexts.WriteExtension):
                 'write extension to deploy upgrades to existing machines.' %
                 (ssh_host, vm_name))
 
+    def check_can_create_file_at_given_path(self, ssh_host, vm_path):
+
+        def check_can_write_to_given_path():
+            try:
+                cliapp.ssh_runcmd(ssh_host, ['touch', vm_path])
+            except cliapp.AppException as e:
+                raise cliapp.AppException("Can't write to location %s on %s"
+                                          % (vm_path, ssh_host))
+            else:
+                cliapp.ssh_runcmd(ssh_host, ['rm', vm_path])
+
+        try:
+            cliapp.ssh_runcmd(ssh_host, ['test', '-e', vm_path])
+        except cliapp.AppException as e:
+            # vm_path doesn't already exist, so let's test we can write
+            check_can_write_to_given_path()
+        else:
+            raise cliapp.AppException('%s already exists on %s'
+                                      % (vm_path, ssh_host))
+
     def check_extra_disks_exist(self, ssh_host, filename_list):
         for filename in filename_list:
             try: