Move annotation generation to producer package

Signed-off-by: Evan Lezar <elezar@nvidia.com>

Author: elezar

api/producer/annotations.go

@@ -17,12 +17,101 @@
 package producer
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 
 	"tags.cncf.io/container-device-interface/api/producer/k8s"
 )
 
+const (
+	// AnnotationPrefix is the prefix for CDI container annotation keys.
+	AnnotationPrefix = "cdi.k8s.io/"
+)
+
+// UpdateAnnotations updates annotations with a plugin-specific CDI device
+// injection request for the given devices. Upon any error a non-nil error
+// is returned and annotations are left intact. By convention plugin should
+// be in the format of "vendor.device-type".
+func UpdateAnnotations(annotations map[string]string, plugin string, deviceID string, devices []string) (map[string]string, error) {
+	key, err := AnnotationKey(plugin, deviceID)
+	if err != nil {
+		return annotations, fmt.Errorf("CDI annotation failed: %w", err)
+	}
+	if _, ok := annotations[key]; ok {
+		return annotations, fmt.Errorf("CDI annotation failed, key %q used", key)
+	}
+	value, err := AnnotationValue(devices)
+	if err != nil {
+		return annotations, fmt.Errorf("CDI annotation failed: %w", err)
+	}
+
+	if annotations == nil {
+		annotations = make(map[string]string)
+	}
+	annotations[key] = value
+
+	return annotations, nil
+}
+
+// AnnotationKey returns a unique annotation key for an device allocation
+// by a K8s device plugin. pluginName should be in the format of
+// "vendor.device-type". deviceID is the ID of the device the plugin is
+// allocating. It is used to make sure that the generated key is unique
+// even if multiple allocations by a single plugin needs to be annotated.
+func AnnotationKey(pluginName, deviceID string) (string, error) {
+	const maxNameLen = 63
+
+	if pluginName == "" {
+		return "", errors.New("invalid plugin name, empty")
+	}
+	if deviceID == "" {
+		return "", errors.New("invalid deviceID, empty")
+	}
+
+	name := pluginName + "_" + strings.ReplaceAll(deviceID, "/", "_")
+
+	if len(name) > maxNameLen {
+		return "", fmt.Errorf("invalid plugin+deviceID %q, too long", name)
+	}
+
+	if c := rune(name[0]); !isAlphaNumeric(c) {
+		return "", fmt.Errorf("invalid name %q, first '%c' should be alphanumeric",
+			name, c)
+	}
+	if len(name) > 2 {
+		for _, c := range name[1 : len(name)-1] {
+			switch {
+			case isAlphaNumeric(c):
+			case c == '_' || c == '-' || c == '.':
+			default:
+				return "", fmt.Errorf("invalid name %q, invalid character '%c'",
+					name, c)
+			}
+		}
+	}
+	if c := rune(name[len(name)-1]); !isAlphaNumeric(c) {
+		return "", fmt.Errorf("invalid name %q, last '%c' should be alphanumeric",
+			name, c)
+	}
+
+	return AnnotationPrefix + name, nil
+}
+
+// AnnotationValue returns an annotation value for the given devices.
+func AnnotationValue(devices []string) (string, error) {
+	value, sep := "", ""
+	for _, d := range devices {
+		if err := ValidateQualifiedName(d); err != nil {
+			return "", err
+		}
+		value += sep + d
+		sep = ","
+	}
+
+	return value, nil
+}
+
 // ValidateSpecAnnotations checks whether spec annotations are valid.
 func ValidateSpecAnnotations(name string, any interface{}) error {
 	if any == nil {