ConfigDrive: write 'injected' files and legacy networking

Previous commit disabled the consumption of 'injected' files in 
configdrive (openstack server boot --file=/target/file=local-file)
unless the datasource was in 'pass' mode.  The default mode is 'net'
so that would never happen.

Also here are:
a.) a fix for 'links_path_prefix' string from debian, to finally
    disable the rendering of systemd.link files (LP: #1594546)
b.) some comments to apply_network_config
c.) implement a backwards compatibility for for distros that do
    not yet implement apply_network_config by converting the network
    config into ENI format and calling apply_network.

    This is required because prior to the previous commit, those distros
    would have had 'apply_network' called with the openstack provided
    ENI file.  But after this change they will have apply_network_config
    called by cloudinit's main.
d.) a network_state_to_eni helper for converting net config to eni
    it supports the not-actually-correct 'hwaddress' field in ENI.

LP: #1602373

2 files changed, 26 insertions, 3 deletions

diff --git a/cloudinit/distros/__init__.py b/cloudinit/distros/__init__.py
index 14b500f8..006a7062 100644
--- a/cloudinit/distros/__init__.py
+++ b/cloudinit/distros/__init__.py
@@ -32,6 +32,8 @@ import stat
 from cloudinit import importer
 from cloudinit import log as logging
 from cloudinit import net
+from cloudinit.net import eni
+from cloudinit.net import network_state
 from cloudinit import ssh_util
 from cloudinit import type_utils
 from cloudinit import util
@@ -138,9 +140,30 @@ class Distro(object):
             return self._bring_up_interfaces(dev_names)
         return False
 
+    def _apply_network_from_network_config(self, netconfig, bring_up=True):
+        LOG.warn("apply_network_config is not currently implemented "
+                 "for distribution '%s'.  Attempting to use "
+                 "apply_network", self.__class__)
+        header = '\n'.join([
+            "# Converted from network_config for distro %s" % self.__class__,
+            "# Implmentation of _write_network_config is needed."
+        ])
+        ns = network_state.parse_net_config_data(netconfig)
+        contents = eni.network_state_to_eni(
+            ns, header=header, render_hwaddress=True)
+        self.apply_network(contents, bring_up=bring_up)
+
     def apply_network_config(self, netconfig, bring_up=False):
-        # Write it out
-        dev_names = self._write_network_config(netconfig)
+        # apply network config netconfig
+        # This method is preferred to apply_network which only takes
+        # a much less complete network config format (interfaces(5)).
+        try:
+            dev_names = self._write_network_config(netconfig)
+        except NotImplementedError:
+            # backwards compat until all distros have apply_network_config
+            return self._apply_network_from_network_config(
+                netconfig, bring_up=bring_up)
+
         # Now try to bring them up
         if bring_up:
             return self._bring_up_interfaces(dev_names)
diff --git a/cloudinit/distros/debian.py b/cloudinit/distros/debian.py
index 5ae9a509..4d336b5b 100644
--- a/cloudinit/distros/debian.py
+++ b/cloudinit/distros/debian.py
@@ -67,7 +67,7 @@ class Distro(distros.Distro):
         self._net_renderer = eni.Renderer({
             'eni_path': self.network_conf_fn,
             'eni_header': ENI_HEADER,
-            'links_prefix_path': None,
+            'links_path_prefix': None,
             'netrules_path': None,
         })