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, 9 insertions, 9 deletions

diff --git a/doc/rtd/topics/capabilities.rst b/doc/rtd/topics/capabilities.rst
index b8034b07..31eaba53 100644
--- a/doc/rtd/topics/capabilities.rst
+++ b/doc/rtd/topics/capabilities.rst
@@ -51,15 +51,6 @@ described in this document.
   usage: cloud-init [-h] [--version] [--file FILES] [--debug] [--force]
                     {init,modules,query,single,dhclient-hook,features} ...
 
-  positional arguments:
-    {init,modules,query,single,dhclient-hook,features}
-      init                initializes cloud-init and performs initial modules
-      modules             activates modules using a given configuration key
-      query               query information stored in cloud-init
-      single              run a single module
-      dhclient-hook       run the dhclient hookto record network info
-      features            list defined features
-
   optional arguments:
     -h, --help            show this help message and exit
     --version, -v         show program's version number and exit
@@ -69,6 +60,15 @@ described in this document.
     --force               force running even if no datasource is found (use at
                           your own risk)
 
+  Subcommands:
+    {init,modules,single,dhclient-hook,features,analyze,devel}
+      init                initializes cloud-init and performs initial modules
+      modules             activates modules using a given configuration key
+      single              run a single module
+      dhclient-hook       run the dhclient hookto record network info
+      features            list defined features
+      analyze             Devel tool: Analyze cloud-init logs and data
+      devel               Run development tools
 
   % cloud-init features
   NETWORK_CONFIG_V1