Add single-stack IPv6 support

docs/release-notes.md

@@ -11,6 +11,7 @@ nav_order: 9
 ### Features
 
 - Support partitioning disk with mounted partitions
+- Support IPv6 for single-stack OpenStack
 
 ### Changes
 

internal/providers/openstack/openstack.go

@@ -44,11 +44,16 @@ const (
 )
 
 var (
-	metadataServiceUrl = url.URL{
+	ipv4MetadataServiceUrl = url.URL{
 		Scheme: "http",
 		Host:   "169.254.169.254",
 		Path:   "openstack/latest/user_data",
 	}
+	ipv6MetadataServiceUrl = url.URL{
+		Scheme: "http",
+		Host:   "[fe80::a9fe:a9fe]",
+		Path:   "openstack/latest/user_data",
+	}
 )
 
 func init() {
@@ -167,13 +172,25 @@ func fetchConfigFromDevice(logger *log.Logger, ctx context.Context, path string)
 }
 
 func fetchConfigFromMetadataService(f *resource.Fetcher) ([]byte, error) {
-	res, err := f.FetchToBuffer(metadataServiceUrl, resource.FetchOptions{})
+	var res []byte
+	var err error
+
+	// Try IPv4 endpoint
+	res, err = f.FetchToBuffer(ipv4MetadataServiceUrl, resource.FetchOptions{})
+	if err == nil {
+		return res, nil
+	} else if err == resource.ErrNotFound {
+		return nil, nil
+	}
 
-	// the metadata server exists but doesn't contain any actual metadata,
-	// assume that there is no config specified
-	if err == resource.ErrNotFound {
+	// If IPv4 fails, try IPv6 endpoint
+	res, err = f.FetchToBuffer(ipv6MetadataServiceUrl, resource.FetchOptions{})
+	if err == nil {
+		return res, nil
+	} else if err == resource.ErrNotFound {
 		return nil, nil
 	}
 
+	// If both endpoints fail, it will return the appropriate error
 	return res, err
 }