build: use legacy builder for wcow if not opt-in with a builder compo…

…nent

Signed-off-by: CrazyMax <[email protected]>

cmd/docker/builder.go

@@ -41,8 +41,7 @@ func newBuilderError(warn bool, err error) error {
 }
 
 func processBuilder(dockerCli command.Cli, cmd *cobra.Command, args, osargs []string) ([]string, []string, error) {
-	var useLegacy bool
-	var useBuilder bool
+	var useLegacy, useBuilder bool
 
 	// check DOCKER_BUILDKIT env var is present and
 	// if not assume we want to use the builder component
@@ -73,6 +72,12 @@ func processBuilder(dockerCli command.Cli, cmd *cobra.Command, args, osargs []st
 		return args, osargs, nil
 	}
 
+	// wcow build command must use the legacy builder
+	// if not opt-in through a builder component
+	if !useBuilder && dockerCli.ServerInfo().OSType == "windows" {
+		return args, osargs, nil
+	}
+
 	if useLegacy {
 		// display warning if not wcow and continue
 		if dockerCli.ServerInfo().OSType != "windows" {