wip adding docker run commands [ci skip]

engine/image.go

@@ -0,0 +1,34 @@
+// Copyright 2019 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by the Polyform License
+// that can be found in the LICENSE file.
+
+package engine
+
+import (
+	"strings"
+
+	"github.com/docker/distribution/reference"
+)
+
+// helper function parses the image and returns the
+// canonical image name, domain name, and whether or not
+// the image tag is :latest.
+func parseImage(s string) (canonical, domain string, latest bool, err error) {
+	// parse the docker image name. We need to extract the
+	// image domain name and match to registry credentials
+	// stored in the .docker/config.json object.
+	named, err := reference.ParseNormalizedNamed(s)
+	if err != nil {
+		return
+	}
+	// the canonical image name, for some reason, excludes
+	// the tag name. So we need to make sure it is included
+	// in the image name so we can determine if the :latest
+	// tag is specified
+	named = reference.TagNameOnly(named)
+
+	return named.String(),
+		reference.Domain(named),
+		strings.HasSuffix(named.String(), ":latest"),
+		nil
+}