Add support for snap create-user on Ubuntu Core images.

Ubuntu Core images use the `snap create-user` to add users to an
Ubuntu Core system. Add support for creating snap users by adding
a key to the users dictionary.
  users:
    - name: bob
      snapuser: bob@bobcom.io

Or via the 'snappy' dictionary:
  snappy:
    email: bob@bobcom.io

Users may also create a snap user without contacting the SSO by
providing a 'system-user' assertion by importing them into snapd.

Additionally, Ubuntu Core systems have a read-only /etc/passwd such that
the normal useradd/groupadd commands do not function without an additional
flag, '--extrausers', which redirects the pwd to /var/lib/extrausers.

Move the system_is_snappy() check from cc_snappy module to util for
re-use and then update the Distro class to append '--extrausers' if
the system is Ubuntu Core.

1 files changed, 65 insertions, 0 deletions

diff --git a/tests/unittests/test_distros/test_user_data_normalize.py b/tests/unittests/test_distros/test_user_data_normalize.py
index b24888fc..33bf922d 100755
--- a/tests/unittests/test_distros/test_user_data_normalize.py
+++ b/tests/unittests/test_distros/test_user_data_normalize.py
@@ -4,6 +4,7 @@ from cloudinit import helpers
 from cloudinit import settings
 
 from ..helpers import TestCase
+import mock
 
 
 bcfg = {
@@ -296,3 +297,67 @@ class TestUGNormalize(TestCase):
         self.assertIn('bob', users)
         self.assertEqual({'default': False}, users['joe'])
         self.assertEqual({'default': False}, users['bob'])
+
+    @mock.patch('cloudinit.util.subp')
+    def test_create_snap_user(self, mock_subp):
+        mock_subp.side_effect = [('{"username": "joe", "ssh-key-count": 1}\n',
+                                  '')]
+        distro = self._make_distro('ubuntu')
+        ug_cfg = {
+            'users': [
+                {'name': 'joe', 'snapuser': 'joe@joe.com'},
+            ],
+        }
+        (users, _groups) = self._norm(ug_cfg, distro)
+        for (user, config) in users.items():
+            print('user=%s config=%s' % (user, config))
+            username = distro.create_user(user, **config)
+
+        snapcmd = ['snap', 'create-user', '--sudoer', '--json', 'joe@joe.com']
+        mock_subp.assert_called_with(snapcmd, capture=True, logstring=snapcmd)
+        self.assertEqual(username, 'joe')
+
+    @mock.patch('cloudinit.util.subp')
+    def test_create_snap_user_known(self, mock_subp):
+        mock_subp.side_effect = [('{"username": "joe", "ssh-key-count": 1}\n',
+                                  '')]
+        distro = self._make_distro('ubuntu')
+        ug_cfg = {
+            'users': [
+                {'name': 'joe', 'snapuser': 'joe@joe.com', 'known': True},
+            ],
+        }
+        (users, _groups) = self._norm(ug_cfg, distro)
+        for (user, config) in users.items():
+            print('user=%s config=%s' % (user, config))
+            username = distro.create_user(user, **config)
+
+        snapcmd = ['snap', 'create-user', '--sudoer', '--json', '--known',
+                   'joe@joe.com']
+        mock_subp.assert_called_with(snapcmd, capture=True, logstring=snapcmd)
+        self.assertEqual(username, 'joe')
+
+    @mock.patch('cloudinit.util.system_is_snappy')
+    @mock.patch('cloudinit.util.is_group')
+    @mock.patch('cloudinit.util.subp')
+    def test_add_user_on_snappy_system(self, mock_subp, mock_isgrp,
+                                       mock_snappy):
+        mock_isgrp.return_value = False
+        mock_subp.return_value = True
+        mock_snappy.return_value = True
+        distro = self._make_distro('ubuntu')
+        ug_cfg = {
+            'users': [
+                {'name': 'joe', 'groups': 'users', 'create_groups': True},
+            ],
+        }
+        (users, _groups) = self._norm(ug_cfg, distro)
+        for (user, config) in users.items():
+            print('user=%s config=%s' % (user, config))
+            distro.add_user(user, **config)
+
+        groupcmd = ['groupadd', 'users', '--extrausers']
+        addcmd = ['useradd', 'joe', '--extrausers', '--groups', 'users', '-m']
+
+        mock_subp.assert_any_call(groupcmd)
+        mock_subp.assert_any_call(addcmd, logstring=addcmd)