[openstack-dev] [nova][neutron][cloud-init] Questions around 'network_data.json'

Joshua Harlow harlowja at fastmail.com
Tue May 24 21:20:47 UTC 2016

Hi there all,

I am working through code/refactoring in cloud-init to enable 
translation of the network_data.json file[1] provided by openstack (via 
nova via neutron?) into the equivalent sysconfig files (ubuntu files 
should already *mostly* work and systemd files are underway as well).

Code for this sysconfig (WIP) is @ 
(requires base branch 
which did some tweaks to make things easier to work with).

Sadly there has been some questions around certain format conversion and 
what it means when certain formats are given, for example in the 
following example:

   "services": [
       "type": "dns",
       "address": ""
   "networks": [
       "network_id": "dacd568d-5be6-4786-91fe-750c374b78b4",
       "type": "ipv4",
       "netmask": "",
       "link": "tap1a81968a-79",
       "routes": [
           "netmask": "",
           "network": "",
           "gateway": ""
       "ip_address": "",
       "id": "network0"
   "links": [
       "ethernet_mac_address": "fa:16:3e:ed:9a:59",
       "mtu": null,
       "type": "bridge",
       "id": "tap1a81968a-79",
       "vif_id": "1a81968a-797a-400f-8a80-567f997eb93f"

In the cloud-init code what happens is that the links get connected to 
the networks and this gets then internally parsed, but for the bridge 
type listed here it appears information is missing about exactly what to 
bridge to (eth0, ethX? something else)?

Should the 'bridge' type just be ignored and it should just be treated 
as a physical device type (which will cause a different set of logic in 
cloud-init to apply); something else?

Thoughts would be appreciated,



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