adding LABEL command

pkg/commands/commands.go

@@ -42,6 +42,8 @@ func GetCommand(cmd instructions.Command) (DockerCommand, error) {
 		return &ExposeCommand{cmd: c}, nil
 	case *instructions.EnvCommand:
 		return &EnvCommand{cmd: c}, nil
+	case *instructions.LabelCommand:
+		return &LabelCommand{cmd: c}, nil
 	}
 	return nil, errors.Errorf("%s is not a supported command", cmd.Name())
 }

pkg/commands/expose.go

@@ -69,6 +69,6 @@ func (r *ExposeCommand) FilesToSnapshot() []string {
 }
 
 func (r *ExposeCommand) CreatedBy() string {
-	s := []string{"/bin/sh", "-c"}
+	s := []string{r.cmd.Name()}
 	return strings.Join(append(s, r.cmd.Ports...), " ")
 }

pkg/commands/label.go

@@ -0,0 +1,72 @@
+/*
+Copyright 2018 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package commands
+
+import (
+	"github.com/containers/image/manifest"
+	"github.com/docker/docker/builder/dockerfile/instructions"
+	"github.com/docker/docker/builder/dockerfile/shell"
+	"github.com/sirupsen/logrus"
+	"strings"
+)
+
+type LabelCommand struct {
+	cmd *instructions.LabelCommand
+}
+
+func (r *LabelCommand) ExecuteCommand(config *manifest.Schema2Config) error {
+	return updateLabels(r.cmd.Labels, config)
+}
+
+func updateLabels(labels []instructions.KeyValuePair, config *manifest.Schema2Config) error {
+	existingLabels := config.Labels
+
+	// Let's unescape values before setting the label
+	shlex := shell.NewLex('\\')
+	for index, kvp := range labels {
+		unescaped, err := shlex.ProcessWord(kvp.Value, []string{})
+		if err != nil {
+			return err
+		}
+		labels[index] = instructions.KeyValuePair{
+			Key:   kvp.Key,
+			Value: unescaped,
+		}
+	}
+	for _, kvp := range labels {
+		logrus.Infof("Applying label %s=%s", kvp.Key, kvp.Value)
+		existingLabels[kvp.Key] = kvp.Value
+	}
+
+	config.Labels = existingLabels
+	return nil
+
+}
+
+// No files have changed, this command only touches metadata.
+func (r *LabelCommand) FilesToSnapshot() []string {
+	return []string{}
+}
+
+// CreatedBy returns some information about the command for the image config history
+func (r *LabelCommand) CreatedBy() string {
+	l := []string{r.cmd.Name()}
+	for _, kvp := range r.cmd.Labels {
+		l = append(l, kvp.String())
+	}
+	return strings.Join(l, " ")
+}

pkg/commands/label_test.go

@@ -0,0 +1,55 @@
+/*
+Copyright 2018 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package commands
+
+import (
+	"github.com/GoogleCloudPlatform/k8s-container-builder/testutil"
+	"github.com/containers/image/manifest"
+	"github.com/docker/docker/builder/dockerfile/instructions"
+	"testing"
+)
+
+func TestUpdateLabels(t *testing.T) {
+	cfg := &manifest.Schema2Config{
+		Labels: map[string]string{
+			"foo": "bar",
+		},
+	}
+
+	labels := []instructions.KeyValuePair{
+		{
+			Key:   "foo",
+			Value: "override",
+		},
+		{
+			Key:   "bar",
+			Value: "baz",
+		},
+		{
+			Key:   "multiword",
+			Value: "lots\\ of\\ words",
+		},
+	}
+
+	expectedLabels := map[string]string{
+		"foo":       "override",
+		"bar":       "baz",
+		"multiword": "lots of words",
+	}
+	updateLabels(labels, cfg)
+	testutil.CheckErrorAndDeepEqual(t, false, nil, expectedLabels, cfg.Labels)
+}