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, 26 insertions, 0 deletions

diff --git a/cloudinit/cmd/devel/parser.py b/cloudinit/cmd/devel/parser.py
new file mode 100644
index 00000000..acacc4ed
--- /dev/null
+++ b/cloudinit/cmd/devel/parser.py
@@ -0,0 +1,26 @@
+# Copyright (C) 2017 Canonical Ltd.
+#
+# This file is part of cloud-init. See LICENSE file for license information.
+
+"""Define 'devel' subcommand argument parsers to include in cloud-init cmd."""
+
+import argparse
+from cloudinit.config.schema import (
+    get_parser as schema_parser, handle_schema_args)
+
+
+def get_parser(parser=None):
+    if not parser:
+        parser = argparse.ArgumentParser(
+            prog='cloudinit-devel',
+            description='Run development cloud-init tools')
+    subparsers = parser.add_subparsers(title='Subcommands', dest='subcommand')
+    subparsers.required = True
+
+    parser_schema = subparsers.add_parser(
+        'schema', help='Validate cloud-config files or document schema')
+    # Construct schema subcommand parser
+    schema_parser(parser_schema)
+    parser_schema.set_defaults(action=('schema', handle_schema_args))
+
+    return parser