instance-data: add cloud-init merged_cfg and sys_info keys to json (#214)

Cloud-config userdata provided as jinja templates are now distro,
platform and merged cloud config aware. The cloud-init query command
will also surface this config data.

Now users can selectively render portions of cloud-config based on:
* distro name, version, release
* python version
* merged cloud config values
* machine platform
* kernel

To support template handling of this config, add new top-level
keys to /run/cloud-init/instance-data.json.

The new 'merged_cfg' key represents merged cloud config from
/etc/cloud/cloud.cfg and /etc/cloud/cloud.cfg.d/*.

The new 'sys_info' key which captures distro and platform
info from cloudinit.util.system_info.

Cloud config userdata templates can render conditional content
based on these additional environmental checks such as the following
simple example:

```
  ## template: jinja
  #cloud-config
   runcmd:
  {% if distro == 'opensuse' %}
    - sh /custom-setup-sles
  {% elif distro == 'centos' %}
    - sh /custom-setup-centos
  {% elif distro == 'debian' %}
    - sh /custom-setup-debian
  {% endif %}
```

To see all values: sudo cloud-init query --all

Any keys added to the standardized v1 keys are guaranteed to not
change or drop on future released of cloud-init. 'v1' keys will be retained
for backward-compatibility even if a new standardized 'v2' set of keys
are introduced

The following standardized v1 keys are added:
* distro, distro_release, distro_version, kernel_version, machine,
python_version, system_platform, variant

LP: #1865969

1 files changed, 1 insertions, 1 deletions

diff --git a/cloudinit/util.py b/cloudinit/util.py
index c02b3d9a..132f6051 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -656,7 +656,7 @@ def system_info():
         'system': platform.system(),
         'release': platform.release(),
         'python': platform.python_version(),
-        'uname': platform.uname(),
+        'uname': list(platform.uname()),
         'dist': get_linux_distro()
     }
     system = info['system'].lower()