Add dockerimage.Push

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## v0.0.5 - Migrate `dockerimage` to _sherlock-mavrodi_
 
 - Add function `dockerimage.BuildFromContainerfile` for building Container Image.
+- Add function `dockerimage.Push` for pushing a Container Image.
 
 **Bugfixes**
 - Correct docs of `StreamContainerLog`

pkg/dockerimage/push.go

@@ -0,0 +1,49 @@
+package dockerimage
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"os"
+	"strings"
+)
+
+const (
+	// remoteDigestPrefix is the line start we search for to get the remote
+	// digest
+	remoteDigestPrefix = "latest: digest: sha256:"
+)
+
+// Push calls docker and pushes a tag.
+// Returns the remote digest for the pushed image.
+func Push(tag string) (string, error) {
+
+	r, w := io.Pipe()
+	defer r.Close()
+	defer w.Close()
+
+	digest := make(chan string)
+	defer close(digest)
+	go func() {
+		scanner := bufio.NewScanner(r)
+		for scanner.Scan() {
+			if !strings.HasPrefix(scanner.Text(), remoteDigestPrefix) {
+				continue
+			}
+
+			digest <- scanner.Text()[len(remoteDigestPrefix) : len(remoteDigestPrefix)+64]
+			return
+		}
+	}()
+	err := executeDockerCommandWithStdout(io.MultiWriter(os.Stdout, w), "push", tag)
+	if err != nil {
+		return "", err
+	}
+
+	select {
+	case d := <-digest:
+		return d, nil
+	default:
+		return "", errors.New("No digest in output found")
+	}
+}