refactor: extract code from the container package

pkg/registry/registry.go

@@ -0,0 +1,33 @@
+package registry
+
+import (
+	"github.com/docker/docker/api/types"
+	log "github.com/sirupsen/logrus"
+)
+
+// GetPullOptions creates a struct with all options needed for pulling images from a registry
+func GetPullOptions(imageName string) (types.ImagePullOptions, error) {
+	auth, err := EncodedAuth(imageName)
+	log.Debugf("Got image name: %s", imageName)
+	if err != nil {
+		return types.ImagePullOptions{}, err
+	}
+
+	log.Debugf("Got auth value: %s", auth)
+	if auth == "" {
+		return types.ImagePullOptions{}, nil
+	}
+
+	return types.ImagePullOptions{
+		RegistryAuth:  auth,
+		PrivilegeFunc: DefaultAuthHandler,
+	}, nil
+}
+
+// DefaultAuthHandler will be invoked if an AuthConfig is rejected
+// It could be used to return a new value for the "X-Registry-Auth" authentication header,
+// but there's no point trying again with the same value as used in AuthConfig
+func DefaultAuthHandler() (string, error) {
+	log.Debug("Authentication request was rejected. Trying again without authentication")
+	return "", nil
+}