docker ps: add "Platform" as formatting option

    docker ps --format 'table {{.ID}}\t{{.Image}}{{.Command}}\t{{.RunningFor}}\t{{.Status}}\t{{.Ports}}\t{{.Names}}\t{{.Platform}}'
    CONTAINER ID   IMAGECOMMAND                CREATED          STATUS          PORTS     NAMES              PLATFORM
    e422855eac55   docker-cli-dev"/bin/bash"   12 minutes ago   Up 12 minutes             strange_jennings   linux/arm64

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: jsternberg

cli/command/formatter/container.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/containerd/platforms"
 	"github.com/distribution/reference"
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/pkg/stringid"
@@ -26,6 +27,7 @@ const (
 	mountsHeader     = "MOUNTS"
 	localVolumes     = "LOCAL VOLUMES"
 	networksHeader   = "NETWORKS"
+	platformHeader   = "PLATFORM"
 )
 
 // NewContainerFormat returns a Format for rendering using a Context
@@ -111,6 +113,7 @@ func NewContainerContext() *ContainerContext {
 		"Mounts":       mountsHeader,
 		"LocalVolumes": localVolumes,
 		"Networks":     networksHeader,
+		"Platform":     platformHeader,
 	}
 	return &containerCtx
 }
@@ -210,6 +213,17 @@ func (c *ContainerContext) RunningFor() string {
 	return units.HumanDuration(time.Now().UTC().Sub(createdAt)) + " ago"
 }
 
+// Platform returns a human-readable representation of the platform
+// of the container if it is available.
+//
+// TODO(thaJeztah): should this take arguments to control "how" it's formatted?
+func (c *ContainerContext) Platform() string {
+	if c.c.ImageManifestDescriptor != nil && c.c.ImageManifestDescriptor.Platform != nil {
+		return platforms.FormatAll(*c.c.ImageManifestDescriptor.Platform)
+	}
+	return ""
+}
+
 // Ports returns a comma-separated string representing open ports of the container
 // e.g. "0.0.0.0:80->9090/tcp, 9988/tcp"
 // it's used by command 'docker ps'