schema cli: Add schema subcommand to cloud-init cli and cc_runcmd schema

This branch does a few things:
  - Add 'schema' subcommand to cloud-init CLI for validating
    cloud-config files against strict module jsonschema definitions
  - Add --annotate parameter to 'cloud-init schema' to annotate
    existing cloud-config file content with validation errors
  - Add jsonschema definition to cc_runcmd
  - Add unit test coverage for cc_runcmd
  - Update CLI capabilities documentation

This branch only imports development (and analyze) subparsers when the
specific subcommand is provided on the CLI to avoid adding costly unused
file imports during cloud-init system boot.

The schema command allows a person to quickly validate a cloud-config text
file against cloud-init's known module schemas to avoid costly roundtrips
deploying instances in their cloud of choice. As of this branch, only
cc_ntp and cc_runcmd cloud-config modules define schemas. Schema
validation will ignore all undefined config keys until all modules define
a strict schema.

To perform validation of runcmd and ntp sections of a cloud-config file:
$ cat > cloud.cfg <<EOF
runcmd: bogus
EOF
$ python -m cloudinit.cmd.main schema --config-file cloud.cfg

$ python -m cloudinit.cmd.main schema --config-file cloud.cfg \
  --annotate

Once jsonschema is defined for all ~55 cc modules, we will move this
schema subcommand up as a proper subcommand of the cloud-init CLI.

1 files changed, 20 insertions, 1 deletions

diff --git a/tests/unittests/test_cli.py b/tests/unittests/test_cli.py
index 7780f164..24498802 100644
--- a/tests/unittests/test_cli.py
+++ b/tests/unittests/test_cli.py
@@ -46,7 +46,7 @@ class TestCLI(test_helpers.FilesystemMockingTestCase):
         self._call_main()
         error = self.stderr.getvalue()
         expected_subcommands = ['analyze', 'init', 'modules', 'single',
-                                'dhclient-hook', 'features']
+                                'dhclient-hook', 'features', 'devel']
         for subcommand in expected_subcommands:
             self.assertIn(subcommand, error)
 
@@ -79,6 +79,25 @@ class TestCLI(test_helpers.FilesystemMockingTestCase):
         for subcommand in expected_subcommands:
             self.assertIn(subcommand, error)
 
+    def test_devel_subcommand_parser(self):
+        """The subcommand cloud-init devel calls the correct subparser."""
+        self._call_main(['cloud-init', 'devel'])
+        # These subcommands only valid for cloud-init schema script
+        expected_subcommands = ['schema']
+        error = self.stderr.getvalue()
+        for subcommand in expected_subcommands:
+            self.assertIn(subcommand, error)
+
+    @mock.patch('cloudinit.config.schema.handle_schema_args')
+    def test_wb_devel_schema_subcommand_parser(self, m_schema):
+        """The subcommand cloud-init schema calls the correct subparser."""
+        exit_code = self._call_main(['cloud-init', 'devel', 'schema'])
+        self.assertEqual(1, exit_code)
+        # Known whitebox output from schema subcommand
+        self.assertEqual(
+            'Expected either --config-file argument or --doc\n',
+            self.stderr.getvalue())
+
     @mock.patch('cloudinit.cmd.main.main_single')
     def test_single_subcommand(self, m_main_single):
         """The subcommand 'single' calls main_single with valid args."""