1 files changed, 47 insertions, 0 deletions
diff --git a/morphlib/exts/kvm.check b/morphlib/exts/kvm.check
index be7c51c2..957d0893 100755
--- a/morphlib/exts/kvm.check
+++ b/morphlib/exts/kvm.check
@@ -17,11 +17,16 @@
 '''Preparatory checks for Morph 'kvm' write extension'''
 
 import cliapp
+import re
+import urlparse
 
 import morphlib.writeexts
 
 
 class KvmPlusSshCheckExtension(morphlib.writeexts.WriteExtension):
+
+    location_pattern = '^/(?P<guest>[^/]+)(?P<path>/.+)$'
+
     def process_args(self, args):
         if len(args) != 1:
             raise cliapp.AppException('Wrong number of command line args')
@@ -32,4 +37,46 @@ class KvmPlusSshCheckExtension(morphlib.writeexts.WriteExtension):
                 'Use the `ssh-rsync` write extension to deploy upgrades to an '
                 'existing remote system.')
 
+        location = args[0]
+        ssh_host, vm_name, vm_path = self.check_and_parse_location(location)
+
+        self.check_ssh_connectivity(ssh_host)
+        self.check_no_existing_libvirt_vm(ssh_host, vm_name)
+        self.check_extra_disks_exist(ssh_host, self.parse_attach_disks())
+
+    def check_and_parse_location(self, location):
+        '''Check and parse the location argument to get relevant data.'''
+
+        x = urlparse.urlparse(location)
+
+        if x.scheme != 'kvm+ssh':
+            raise cliapp.AppException(
+                'URL schema must be kvm+ssh in %s' % location)
+
+        m = re.match(self.location_pattern, x.path)
+        if not m:
+            raise cliapp.AppException('Cannot parse location %s' % location)
+
+        return x.netloc, m.group('guest'), m.group('path')
+
+    def check_no_existing_libvirt_vm(self, ssh_host, vm_name):
+        try:
+            cliapp.ssh_runcmd(ssh_host,
+                ['virsh', '--connect', 'qemu:///system', 'domstate', vm_name])
+        except cliapp.AppException as e:
+            pass
+        else:
+            raise cliapp.AppException(
+                'Host %s already has a VM named %s. You can use the ssh-rsync '
+                'write extension to deploy upgrades to existing machines.' %
+                (ssh_host, vm_name))
+
+    def check_extra_disks_exist(self, ssh_host, filename_list):
+        for filename in filename_list:
+            try:
+                cliapp.ssh_runcmd(ssh_host, ['ls', filename])
+            except cliapp.AppException as e:
+                raise cliapp.AppException('Did not find file %s on host %s' %
+                                          (filename, ssh_host))
+
 KvmPlusSshCheckExtension().run()