Make OpenStack LBaaS v2 Provider configurable

Add option 'lb-provider' to the Loadbalancer section of the OpenStack
cloudprovider configuration to allow using a different LBaaS v2
provider than the default.

pkg/cloudprovider/providers/openstack/openstack.go

@@ -82,6 +82,7 @@ type LoadBalancerOpts struct {
 	SubnetId             string     `gcfg:"subnet-id"`           // overrides autodetection.
 	FloatingNetworkId    string     `gcfg:"floating-network-id"` // If specified, will create floating ip for loadbalancer, or do not create floating ip.
 	LBMethod             string     `gcfg:"lb-method"`           // default to ROUND_ROBIN.
+	LBProvider           string     `gcfg:"lb-provider"`
 	CreateMonitor        bool       `gcfg:"create-monitor"`
 	MonitorDelay         MyDuration `gcfg:"monitor-delay"`
 	MonitorTimeout       MyDuration `gcfg:"monitor-timeout"`

pkg/cloudprovider/providers/openstack/openstack_loadbalancer.go

@@ -515,6 +515,7 @@ func (lbaas *LbaasV2) createLoadBalancer(service *v1.Service, name string, inter
 		Name:        name,
 		Description: fmt.Sprintf("Kubernetes external service %s", name),
 		VipSubnetID: lbaas.opts.SubnetId,
+		Provider:    lbaas.opts.LBProvider,
 	}
 
 	loadBalancerIP := service.Spec.LoadBalancerIP

pkg/cloudprovider/providers/openstack/openstack_test.go

@@ -169,6 +169,7 @@ func TestCheckOpenStackOpts(t *testing.T) {
 					SubnetId:             "6261548e-ffde-4bc7-bd22-59c83578c5ef",
 					FloatingNetworkId:    "38b8b5f9-64dc-4424-bf86-679595714786",
 					LBMethod:             "ROUND_ROBIN",
+					LBProvider:           "haproxy",
 					CreateMonitor:        true,
 					MonitorDelay:         delay,
 					MonitorTimeout:       timeout,