Add implied version check

stephenfin · stephenfin · commit 07d1ee0ee6f3 · 2025-05-16T12:48:47.000+01:00
Avoid unnecessary lookups for when we are encoding the version in our
service type.

Signed-off-by: Stephen Finucane &lt;stephenfin@redhat.com&gt;
diff --git a/openstack/endpoint.go b/openstack/endpoint.go
@@ -2,20 +2,64 @@ package openstack
 
 import (
 	"context"
+	"regexp"
 	"slices"
+	"strconv"
 
 	"github.com/gophercloud/gophercloud/v2"
 	tokens2 "github.com/gophercloud/gophercloud/v2/openstack/identity/v2/tokens"
 	tokens3 "github.com/gophercloud/gophercloud/v2/openstack/identity/v3/tokens"
 	"github.com/gophercloud/gophercloud/v2/openstack/utils"
 )
 
+var versionedServiceTypeAliasRegexp = regexp.MustCompile(`^.*v(\d)$`)
+
+func extractServiceTypeVersion(serviceType string) int {
+	matches := versionedServiceTypeAliasRegexp.FindAllStringSubmatch(serviceType, 1)
+	if matches != nil {
+		// no point converting to an int
+		ret, err := strconv.Atoi(matches[0][1])
+		if err != nil {
+			return 0
+		}
+		return ret
+	}
+	return 0
+}
+
 func endpointSupportsVersion(ctx context.Context, client *gophercloud.ProviderClient, serviceType, endpointURL string, expectedVersion int) (bool, error) {
 	// Swift doesn't support version discovery :(
 	if expectedVersion == 0 || serviceType == "object-store" {
 		return true, nil
 	}
 
+	// Repeating verbatim from keystoneauth1 [1]:
+	//
+	// > The sins of our fathers become the blood on our hands.
+	// > If a user requests an old-style service type such as volumev2, then they
+	// > are inherently requesting the major API version 2. It's not a good
+	// > interface, but it's the one that was imposed on the world years ago
+	// > because the client libraries all hid the version discovery document.
+	// > In order to be able to ensure that a user who requests volumev2 does not
+	// > get a block-storage endpoint that only provides v3 of the block-storage
+	// > service, we need to pull the version out of the service_type. The
+	// > service-types-authority will prevent the growth of new monstrosities such
+	// > as this, but in order to move forward without breaking people, we have
+	// > to just cry in the corner while striking ourselves with thorned branches.
+	// > That said, for sure only do this hack for officially known service_types.
+	//
+	// So yeah, what mordred said.
+	//
+	// https://github.com/openstack/keystoneauth/blob/5.10.0/keystoneauth1/discover.py#L270-L290
+	impliedVersion := extractServiceTypeVersion(serviceType)
+	if impliedVersion != 0 && impliedVersion != expectedVersion {
+		return false, nil
+	}
+
+	// NOTE(stephenfin) In addition to the above, keystoneauth also supports a URL
+	// hack whereby it will extract the version from the URL. We may wish to
+	// implement this too.
+
 	endpointURL, err := utils.BaseVersionedEndpoint(endpointURL)
 	if err != nil {
 		return false, err
