improve flannel vxlan conditional logic

[Daneyon Hansen]

Currently, the flannel conditional logic for managing the config json is difficult to understand:

https://github.com/openstack/magnum/blob/master/magnum/templates/kubernetes/fragments/write-network-config.sh#L27-L40

It is recommended to implement improved conditional logic to all bay types that support the flannel network-driver. For example:

if [ "$use_vxlan" = 1 ]; then
    backend_type="vxlan"
else
    backend_type="udp"
fi
cat > $FLANNEL_JSON <<EOF
....
    "Backend": {
         "Type": "$backend_type"
    }
}
EOF

[Eli Qiao (taget-9)]

https://review.openstack.org/241866 will fix this.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/241866
Committed: https://git.openstack.org/cgit/openstack/magnum/commit/?id=14909f0944649b4de7eb5c8785162defaad0d55a
Submitter: Jenkins
Branch: master

commit 14909f0944649b4de7eb5c8785162defaad0d55a
Author: Angus Lees <email address hidden>
Date: Thu Nov 5 15:12:43 2015 +1100

    Add flannel's host-gw backend option

    Allow configuring Flannel with 3 different backends

    Magnum deploys k8s/swarm over a dedicated neutron private network,
    possibly using flannel. Flannel's `host-gw` backend gives the best
    performance in this topopolgy (private layer2): no packet processing
    overhead, no reduction to MTU, scales to many hosts as well as the
    alternatives. The performance difference is significant, see bug for
    performance numbers for the 3 backend options.

    Note that part of this change involves relaxing the minion IP spoofing
    rules to allow traffic from all dynamically-allocated flannel subnets.
    This is morally equivalent to what we were doing previously with
    encapsulation - only now neutron is able to see the inner IP header
    directly.

    This patch repurposes the label "flannel_use_vxlan" when the network
    driver is flannel.

    1. Rename the label flannel_use_vxlan to flannel_backend
    2. Redefine the value of this label from "yes/no"
       to "udp/vxlan/host-gw"

    For example, to create a bay model with flannel as network driver:
    --network-driver flannel --labels flannel_backend=host-gw

    Other backend options are udp and vxlan.

    Co-Authored-By: Ton Ngo <email address hidden>
    Partial-Bug: #1518605
    Closes-Bug: #1516789
    Change-Id: I6d2441664ad1baaca14d0e6ff4bcddbe75bee094

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/magnum 3.0.0 release.