When the interfaces file is generated it is necessary to determine the
mode (vlan or raw) from the interface name. Originally the plugin
considers that a previous interfaces file exists and will use it to
set the mode value.
But on StarlingX network_config is generated by sysinv and there is no
previous file to parse, so this change adds the mode logic on
file formatting.
Test Plan:
PASS: generate valid ifupdown config when interface name is of format
"vlanNNN" on Debian and apply it with ifup/ifdown command
Story: 2009101
Task: 44659
Signed-off-by: Andre Fernando Zanella Kantek <AndreFernandoZanella.Kantek@windriver.com>
Change-Id: Ibccd189ea14eed4b8504908188fabedfa6bf4c2a
d0a4cdcb1e