WIP: Flexible Nova Microversion

Set the microversion using a separate method and use integer maths
instead of strings and floats when comparing versions.

pkg/clients/compute.go

@@ -43,12 +43,19 @@ CAPO uses server tags, which were first added in microversion 2.26 and then refi
 in 2.52 so it is possible to apply them when creating a server (which is what CAPO does).
 CAPO supports multiattach volume types, which were added in microversion 2.60.
 */
-var NovaSupportedVersions = []*utils.Version{
-	{ID: "2.1", Priority: 10, Suffix: "/v2.1/"},   // Initial microversion release, same as specifying no version
-	{ID: "2.53", Priority: 20, Suffix: "/v2.53/"}, // Maximum in Pike
-	{ID: "2.60", Priority: 30, Suffix: "/v2.60/"}, // Maximum in Queens
+var NovaSupportedVersions = map[int]*utils.Version{
+	38: {ID: "2.38", Priority: 10, Suffix: "/v2.38/"}, // Maximum in Newton
+	53: {ID: "2.53", Priority: 20, Suffix: "/v2.53/"}, // Maximum in Pike
+	60: {ID: "2.60", Priority: 30, Suffix: "/v2.60/"}, // Maximum in Queens
 }
 
+// Constants for specific microversion requirement.
+// The values correspond to the decimal part of the Nova version for easy comparisons.
+// For example, we require 2.53 for tagging support, so NovaTagging is set to 53.
+const (
+	NovaTagging = 53
+)
+
 // ServerExt is the base gophercloud Server with extensions used by InstanceStatus.
 type ServerExt struct {
 	servers.Server
@@ -66,6 +73,7 @@ type ComputeClient interface {
 
 	ListAttachedInterfaces(serverID string) ([]attachinterfaces.Interface, error)
 	DeleteAttachedInterface(serverID, portID string) error
+	RequireMicroversion(decimal int) error
 }
 
 type computeClient struct{ client *gophercloud.ServiceClient }
@@ -79,6 +87,18 @@ func NewComputeClient(providerClient *gophercloud.ProviderClient, providerClient
 		return nil, fmt.Errorf("failed to create compute service client: %v", err)
 	}
 
+	// Make an initial version negotiation.
+	// The caller can redo this later with more restrictions via RequireMicroversion.
+	supportedVersions := []*utils.Version{}
+	for k := range NovaSupportedVersions {
+		supportedVersions = append(supportedVersions, NovaSupportedVersions[k])
+	}
+	version, _, err := utils.ChooseVersion(providerClient, supportedVersions)
+	if err != nil {
+		return nil, fmt.Errorf("failed to negotiation compute service version: %w", err)
+	}
+	compute.Microversion = version.ID
+
 	return &computeClient{compute}, nil
 }
 
@@ -153,6 +173,26 @@ func (c computeClient) DeleteAttachedInterface(serverID, portID string) error {
 	return mc.ObserveRequestIgnoreNotFoundorConflict(err)
 }
 
+// RequireMicroversion negotiates the Nova microversion for the ComputeClient while taking into account
+// the version requirement given. The microversion will be set to minimum `2.requiredDecimal`,
+// or an error will be returned.
+func (c computeClient) RequireMicroversion(requiredDecimal int) error {
+	supportedMicroversions := []*utils.Version{}
+	for decimal := range NovaSupportedVersions {
+		if decimal < requiredDecimal {
+			continue
+		}
+		supportedMicroversions = append(supportedMicroversions, NovaSupportedVersions[decimal])
+	}
+	chosen, _, err := utils.ChooseVersion(c.client.ProviderClient, supportedMicroversions)
+	if err != nil {
+		return fmt.Errorf("failed to negotiate compute client version: %v", err)
+	}
+	fmt.Println("TODO: Add proper logging. Chose microversion %s", chosen.ID)
+	c.client.Microversion = chosen.ID
+	return nil
+}
+
 type computeErrorClient struct{ error }
 
 // NewComputeErrorClient returns a ComputeClient in which every method returns the given error.
@@ -191,3 +231,7 @@ func (e computeErrorClient) ListAttachedInterfaces(_ string) ([]attachinterfaces
 func (e computeErrorClient) DeleteAttachedInterface(_, _ string) error {
 	return e.error
 }
+
+func (e computeErrorClient) RequireMicroversion(_ int) error {
+	return e.error
+}

pkg/cloud/services/compute/instance.go

@@ -31,7 +31,6 @@ import (
 	"github.com/gophercloud/gophercloud/openstack/compute/v2/servers"
 	"github.com/gophercloud/gophercloud/openstack/imageservice/v2/images"
 	"github.com/gophercloud/gophercloud/openstack/networking/v2/ports"
-	"github.com/gophercloud/gophercloud/openstack/utils"
 	"k8s.io/apimachinery/pkg/runtime"
 	"sigs.k8s.io/cluster-api/util"
 
@@ -346,19 +345,14 @@ func (s *Service) createInstanceImpl(eventObject runtime.Object, openStackCluste
 
 	serverCreateOpts = applyServerGroupID(serverCreateOpts, instanceSpec.ServerGroupID)
 
-	// Filter supported versions based on features used
-	recognizedMicroversions := clients.NovaSupportedVersions
-	supportedMicroversions := []*utils.Version{}
+	compute := s.getComputeClient()
 	if len(instanceSpec.Tags) > 0 {
-		for i := range recognizedMicroversions {
-			if recognizedMicroversions[i].ID == "2.1" {
-				continue
-			}
-			supportedMicroversions = append(supportedMicroversions, recognizedMicroversions[i])
+		err = compute.RequireMicroversion(clients.NovaTagging)
+		if err != nil {
+			return nil, fmt.Errorf("tagging is not supported by the server: %w", err)
 		}
 	}
-
-	server, err = s.getComputeClient().CreateServer(keypairs.CreateOptsExt{
+	server, err = compute.CreateServer(keypairs.CreateOptsExt{
 		CreateOptsBuilder: serverCreateOpts,
 		KeyName:           instanceSpec.SSHKeyName,
 	})