Merge pull request #52013 from FengyunPan/autoprobing-external-network

Automatic merge from submit-queue (batch tested with PRs 52013, 56719). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Support autoprobing floating-network-id for openstack cloud provider

Currently if user doesn't specify floatingnetwork-id and loadbalancer.openstack.org/floating-network-id annotation, openstack cloud provider can't create a external LoadBalancer service.
Actually we can get  floatingnetwork-id automatically. 
If we get multiple  floatingnetwork-ids, then ask user to specify one, or we use the  floatingnetwork-id to create floatingip for external LoadBalancer service.

This is a part of #50726

**Special notes for your reviewer**:
/assign @dims

**Release note**:
```release-note
Support autoprobing floating-network-id for openstack cloud provider
```

pkg/cloudprovider/providers/openstack/BUILD

@@ -39,6 +39,7 @@ go_library(
         "//vendor/github.com/gophercloud/gophercloud/openstack/identity/v3/extensions/trusts:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/identity/v3/tokens:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions:go_default_library",
+        "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/external:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/layer3/floatingips:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/layer3/routers:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/listeners:go_default_library",
@@ -47,6 +48,7 @@ go_library(
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/pools:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/security/groups:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/security/rules:go_default_library",
+        "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/networks:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/openstack/networking/v2/ports:go_default_library",
         "//vendor/github.com/gophercloud/gophercloud/pagination:go_default_library",
         "//vendor/github.com/mitchellh/mapstructure:go_default_library",

pkg/cloudprovider/providers/openstack/openstack_loadbalancer.go

@@ -25,6 +25,7 @@ import (
 	"github.com/golang/glog"
 	"github.com/gophercloud/gophercloud"
 	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions"
+	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/external"
 	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/layer3/floatingips"
 	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/listeners"
 	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/loadbalancers"
@@ -32,6 +33,7 @@ import (
 	v2pools "github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/pools"
 	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/security/groups"
 	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/security/rules"
+	"github.com/gophercloud/gophercloud/openstack/networking/v2/networks"
 	neutronports "github.com/gophercloud/gophercloud/openstack/networking/v2/ports"
 	"github.com/gophercloud/gophercloud/pagination"
 
@@ -566,6 +568,52 @@ func getNodeSecurityGroupIDForLB(compute *gophercloud.ServiceClient, nodes []*v1
 	return nodeSecurityGroupIDs.List(), nil
 }
 
+// getFloatingNetworkIdForLB returns a floating-network-id for cluster.
+func getFloatingNetworkIdForLB(client *gophercloud.ServiceClient) (string, error) {
+	var floatingNetworkIds []string
+
+	type NetworkWithExternalExt struct {
+		networks.Network
+		external.NetworkExternalExt
+	}
+
+	err := networks.List(client, networks.ListOpts{}).EachPage(func(page pagination.Page) (bool, error) {
+		var externalNetwork []NetworkWithExternalExt
+		err := networks.ExtractNetworksInto(page, &externalNetwork)
+		if err != nil {
+			return false, err
+		}
+
+		for _, externalNet := range externalNetwork {
+			if externalNet.External {
+				floatingNetworkIds = append(floatingNetworkIds, externalNet.ID)
+			}
+		}
+
+		if len(floatingNetworkIds) > 1 {
+			return false, ErrMultipleResults
+		}
+		return true, nil
+	})
+	if err != nil {
+		if isNotFound(err) {
+			return "", ErrNotFound
+		}
+
+		if err == ErrMultipleResults {
+			glog.V(4).Infof("find multiple external networks, pick the first one when there are no explicit configuration.")
+			return floatingNetworkIds[0], nil
+		}
+		return "", err
+	}
+
+	if len(floatingNetworkIds) == 0 {
+		return "", ErrNotFound
+	}
+
+	return floatingNetworkIds[0], nil
+}
+
 // TODO: This code currently ignores 'region' and always creates a
 // loadbalancer in only the current OpenStack region.  We should take
 // a list of regions (from config) and query/create loadbalancers in
@@ -596,7 +644,13 @@ func (lbaas *LbaasV2) EnsureLoadBalancer(clusterName string, apiService *v1.Serv
 	}
 
 	floatingPool := getStringFromServiceAnnotation(apiService, ServiceAnnotationLoadBalancerFloatingNetworkId, lbaas.opts.FloatingNetworkId)
-	glog.V(4).Infof("EnsureLoadBalancer using floatingPool: %v", floatingPool)
+	if len(floatingPool) == 0 {
+		var err error
+		floatingPool, err = getFloatingNetworkIdForLB(lbaas.network)
+		if err != nil {
+			glog.Warningf("Failed to find floating-network-id for loadbalancer service %s/%s: %v", apiService.Namespace, apiService.Name, err)
+		}
+	}
 
 	var internalAnnotation bool
 	internal := getStringFromServiceAnnotation(apiService, ServiceAnnotationLoadBalancerInternal, "false")
@@ -606,7 +660,7 @@ func (lbaas *LbaasV2) EnsureLoadBalancer(clusterName string, apiService *v1.Serv
 		internalAnnotation = true
 	case "false":
 		if len(floatingPool) != 0 {
-			glog.V(4).Infof("Ensure an external loadbalancer service.")
+			glog.V(4).Infof("Ensure an external loadbalancer service, using floatingPool: %v", floatingPool)
 			internalAnnotation = false
 		} else {
 			return nil, fmt.Errorf("floating-network-id or loadbalancer.openstack.org/floating-network-id should be specified when ensuring an external loadbalancer service")