Merge ~wesley-wiedenmeier/cloud-init:feature-flags into ~raharper/cloud-init:netconfig-v2-passthrough

[Wesley Wiedenmeier]

Add feature flag for netconfig-v2

e38617d... by Wesley Wiedenmeier on 2017-02-17

Change feature flag for v2 networking to 'NETWORK_CONFIG_V2' to match curtin

[Wesley Wiedenmeier (wesley-wiedenmeier)]

note that the diff displayed below is incorrect, launchpad isn't updating it for some reason

actual diff:

-[laptop1]- -[~/code/cloud-init]-
-[02:07 PM]-git rev-parse HEAD
e38617d52090b3b01278f6840d46154e83fc31da
-[laptop1]- -[~/code/cloud-init]-
-[02:07 PM]-git diff net_devel/netconfig-v2-passthrough
diff --git a/cloudinit/version.py b/cloudinit/version.py
index 92bace1..dd77f7c 100644
--- a/cloudinit/version.py
+++ b/cloudinit/version.py
@@ -6,6 +6,11 @@

 __VERSION__ = "0.7.9"

+FEATURES = [
+ # supports network config version 2
+ 'NETWORK_CONFIG_V2',
+]
+

 def version_string():
     return __VERSION__

3d496d0... by Wesley Wiedenmeier on 2017-03-03

Added documentation on cloud-init feature flags to capabilities doc

[Chad Smith (chad.smith)]

A features subcommand is now implemented in cloud-init, and includes this content and allows a user to run "cloud-init features" on the commandline.

[Ryan Harper (raharper)]

Launchpad language is harsh, it's not really rejected; but marking it so cleans up our list of active reviews.

Unmerged commits

3d496d0... by Wesley Wiedenmeier on 2017-03-03

Added documentation on cloud-init feature flags to capabilities doc

e38617d... by Wesley Wiedenmeier on 2017-02-17

Change feature flag for v2 networking to 'NETWORK_CONFIG_V2' to match curtin

0199004... by Wesley Wiedenmeier on 2017-02-17

Add feature flags to cloudinit.version and 'netconfig-v2' flag

diff --git a/cloudinit/version.py b/cloudinit/version.py
index 92bace1..dd77f7c 100644
--- a/cloudinit/version.py
+++ b/cloudinit/version.py
@@ -6,6 +6,11 @@
 
 __VERSION__ = "0.7.9"
 
+FEATURES = [
+    # supports network config version 2
+    'NETWORK_CONFIG_V2',
+]
+
 
 def version_string():
     return __VERSION__
diff --git a/doc/rtd/topics/capabilities.rst b/doc/rtd/topics/capabilities.rst
index be0802c..9ce11ec 100644
--- a/doc/rtd/topics/capabilities.rst
+++ b/doc/rtd/topics/capabilities.rst
@@ -7,6 +7,7 @@ Capabilities
 - Generating instance ssh private keys
 - Adding ssh keys to a users ``.ssh/authorized_keys`` so they can log in
 - Setting up ephemeral mount points
+- Configuring network devices
 
 User configurability
 ====================
@@ -22,5 +23,27 @@ ec2-run-instances for example.
   string or `user-data` file for usage by cloud-init on instance creation.
 
 
+Feature detection
+=================
+
+Newer versions of cloud-init may have a list of additional features that they
+support. This allows other applications to detect what features the installed
+cloud-init supports without having to parse its version number. If present,
+this list of features will be located at ``cloudinit.version.FEATURES``.
+
+When checking if cloud-init supports a feature, in order to not break the
+detection script on older versions of cloud-init without the features list, a
+script similar to the following should be used. Note that this will exit 0 if
+the feature is supported and 1 otherwise::
+
+    import sys
+    from cloudinit import version
+    sys.exit('<FEATURE_NAME>' not in getattr(version, 'FEATURES', []))
+
+Currently defined feature names include:
+
+ - ``NETWORK_CONFIG_V2`` support for v2 networking configuration, see netplan
+   docs for examples.
+
 .. _Cloud-init: https://launchpad.net/cloud-init
 .. vi: textwidth=78