Add mapping option to influence nicN mapping order

Currently there's a fixed mapping between abstracted interface
names (nic1, nic2 etc) and the underlying biosdevname for the
device.

In many cases, this mapping based on system enumeration is
sufficient, but in some cases, particularly when you perform
detailed pre-deployment discovery of interfaces, you may wish
to alter the mapping independently of the config (e.g if the
config is in a heat template, and the discovery data is
provided at runtime).

So this adds a -m option to os-net-config, which enables a
mapping file to be provided, such that specific interfaces
may be mapped to their abstract names based on knowledge of
the devices or the networks they are connected to.

The mapping file has the following format, where em1 and em2 are
device names as detected by the OS (e.g biosdevname):

interface_mapping:
    nic1: em2
    nic2: em1

Or you can use the device MAC instead:

interface_mapping:
    nic1: 12:34:56:78:9a:bc
    nic2: 12:34:56:de:f0:12

Change-Id: I93e6d3ed733244834bb3c2126c91db705b4d9167

1 files changed, 19 insertions, 0 deletions

diff --git a/os_net_config/cli.py b/os_net_config/cli.py
index 2df13c9..d22573d 100644
--- a/os_net_config/cli.py
+++ b/os_net_config/cli.py
@@ -38,6 +38,9 @@ def parse_opts(argv):
     parser.add_argument('-c', '--config-file', metavar='CONFIG_FILE',
                         help="""path to the configuration file.""",
                         default='/etc/os-net-config/config.yaml')
+    parser.add_argument('-m', '--mapping-file', metavar='MAPPING_FILE',
+                        help="""path to the interface mapping file.""",
+                        default='/etc/os-net-config/mapping.yaml')
     parser.add_argument('-p', '--provider', metavar='PROVIDER',
                         help="""The provider to use."""
                         """One of: ifcfg, eni, iproute.""",
@@ -94,6 +97,8 @@ def main(argv=sys.argv):
     opts = parse_opts(argv)
     configure_logger(opts.verbose, opts.debug)
     logger.info('Using config file at: %s' % opts.config_file)
+    if opts.mapping_file:
+        logger.info('Using mapping file at: %s' % opts.mapping_file)
     iface_array = []
 
     provider = None
@@ -116,6 +121,7 @@ def main(argv=sys.argv):
             logger.error('Unable to set provider for this operating system.')
             return 1
 
+    # Read config file containing network configs to apply
     if os.path.exists(opts.config_file):
         with open(opts.config_file) as cf:
             iface_array = yaml.load(cf.read()).get("network_config")
@@ -123,10 +129,23 @@ def main(argv=sys.argv):
     else:
         logger.error('No config file exists at: %s' % opts.config_file)
         return 1
+
     if not isinstance(iface_array, list):
         logger.error('No interfaces defined in config: %s' % opts.config_file)
         return 1
+
+    # Read the interface mapping file, if it exists
+    # This allows you to override the default network naming abstraction
+    # mappings by specifying a specific nicN->name or nicN->MAC mapping
+    if os.path.exists(opts.mapping_file):
+        with open(opts.mapping_file) as cf:
+            iface_mapping = yaml.load(cf.read()).get("interface_mapping")
+            logger.debug('interface_mapping JSON: %s' % str(iface_mapping))
+    else:
+        iface_mapping = None
+
     for iface_json in iface_array:
+        iface_json.update({'nic_mapping': iface_mapping})
         obj = objects.object_from_json(iface_json)
         provider.add_object(obj)
     files_changed = provider.apply(noop=opts.noop, cleanup=opts.cleanup)