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

2 files changed, 31 insertions, 0 deletions

diff --git a/etc/os-net-config/samples/bond_mapped.yaml b/etc/os-net-config/samples/bond_mapped.yaml
new file mode 100644
index 0000000..9a118c9
--- /dev/null
+++ b/etc/os-net-config/samples/bond_mapped.yaml
@@ -0,0 +1,23 @@
+# Example showing use of the optional nicN abstraction
+# for device naming, which defaults to an ordered
+# translation to biodev names based on which interfaces
+# are active on the system.
+# Optionally the default mapping may be overriden by
+# a mapping file via the -m option.
+network_config:
+  -
+     type: ovs_bridge
+     name: br-ctlplane
+     use_dhcp: true
+     members:
+       -
+         type: ovs_bond
+         name: bond1
+         use_dhcp: true
+         members:
+           -
+             type: interface
+             name: nic1
+           -
+             type: interface
+             name: nic2
diff --git a/etc/os-net-config/samples/mapping.yaml b/etc/os-net-config/samples/mapping.yaml
new file mode 100644
index 0000000..5faec22
--- /dev/null
+++ b/etc/os-net-config/samples/mapping.yaml
@@ -0,0 +1,8 @@
+# This can be used with the -m option to override the
+# default mapping of the nicN aliases in configs
+# The mapping can specify either a device name or a mac address
+interface_mapping:
+    nic1: em3
+    nic2: em1
+    nic3: 12:34:56:de:f0:12
+    nic4: 12:34:56:78:9a:bc