Determine the internal vlan tag that openstack uses on br-int for a given provider network id

find-internal-tag-for-network.py

from keystoneauth1 import identity
from keystoneauth1 import session
from neutronclient.v2_0 import client
from ovs_vsctl import VSCtl
from argparse import ArgumentParser
import ovs_vsctl.parser as ovs_vsctl_parser
import pdb
import os
"""
If you want to find the internal vlan tag that openstack assigns for a given provider segmentation ID
run this script on the neutron node with the following invocation

python find-internal-tag-for-network.py 300

"""


if __name__ == "__main__":
    parser = ArgumentParser()
    parser.add_argument("network_segementation_id", default=None, help="OpenStack Network ID")
    args = parser.parse_args()
    network_segmentation_id = args.network_segementation_id

    username= os.environ.get("OS_USERNAME")
    password= os.environ.get("OS_PASSWORD")
    project_name= os.environ.get("OS_PROJECT_NAME")
    project_domain_id='default'
    if os.environ.get("OS_PROJECT_DOMAIN_NAME") is not None:
       project_domain_id = os.environ.get("OS_PROJECT_DOMAIN_NAME")
    user_domain_id='default'
    if os.environ.get("OS_USER_DOMAIN_NAME") is not None:
        user_domain_id= os.environ.get("OS_USER_DOMAIN_NAME")
    auth_url= os.environ.get("OS_AUTH_URL")
    if auth_url is None:
       print "Missing auth url ... set OS_AUTH_URL environment variable"
       sys.exit()
    auth = identity.Password(auth_url=auth_url,
                    username=username,
                    password=password,
                    project_name=project_name,
                    project_domain_id=project_domain_id,
                    user_domain_id=user_domain_id)
    sess = session.Session(auth=auth)
    neutron = client.Client(session=sess)
    networks = neutron.list_networks()['networks']
    network_id = 0
    for network in networks:
       if network['provider:segmentation_id'] == int(network_segmentation_id):
          network_id = network['id']

    vsctl = VSCtl('tcp', '127.0.0.1', 6640)

    ports = vsctl.run(command='list port',parser=ovs_vsctl_parser.list_cmd_parser)
    for port in ports:
        other_config = port.other_config
        if 'net_uuid' in other_config and str(other_config['net_uuid']) == network_id:
            print "internal vlan tag = ", other_config['tag']
            break