cmd/ctr, service/containers: implement container filter

Signed-off-by: Stephen J Day <stephen.day@docker.com>

cmd/ctr/labels.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/urfave/cli"
+)
+
+var containersSetLabelsCommand = cli.Command{
+	Name:        "set-labels",
+	Usage:       "Set and clear labels for a container.",
+	ArgsUsage:   "[flags] <name> [<key>=<value>, ...]",
+	Description: "Set and clear labels for a container.",
+	Flags:       []cli.Flag{},
+	Action: func(clicontext *cli.Context) error {
+		var (
+			ctx, cancel         = appContext(clicontext)
+			containerID, labels = objectWithLabelArgs(clicontext)
+		)
+		defer cancel()
+
+		client, err := newClient(clicontext)
+		if err != nil {
+			return err
+		}
+
+		if containerID == "" {
+			return errors.New("please specify a container")
+		}
+
+		container, err := client.LoadContainer(ctx, containerID)
+		if err != nil {
+			return err
+		}
+
+		setlabels, err := container.SetLabels(ctx, labels)
+		if err != nil {
+			return err
+		}
+
+		var labelStrings []string
+		for k, v := range setlabels {
+			labelStrings = append(labelStrings, fmt.Sprintf("%s=%s", k, v))
+		}
+
+		fmt.Println(strings.Join(labelStrings, ","))
+
+		return nil
+	},
+}