Add support for Swarm IDs.

- Every container that gets created through Swarm gets a Swarm ID
  assigned (as a label).
- All API operations (start, stop, ...) can be performed by using either
  the container ID or the swarm ID.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

cluster/engine.go

@@ -463,11 +463,16 @@ func (e *Engine) Container(IDOrName string) *Container {
 	}
 
 	for _, container := range e.Containers() {
-		// Match ID prefix.
+		// Match Container ID prefix.
 		if strings.HasPrefix(container.Id, IDOrName) {
 			return container
 		}
 
+		// Match Swarm ID prefix.
+		if strings.HasPrefix(container.Config.SwarmID(), IDOrName) {
+			return container
+		}
+
 		// Match name, /name or engine/name.
 		for _, name := range container.Names {
 			if name == IDOrName || name == "/"+IDOrName || container.Engine.ID+name == IDOrName || container.Engine.Name+name == IDOrName {

cluster/swarm/cluster.go

@@ -9,6 +9,7 @@ import (
 	"sync"
 
 	log "github.com/Sirupsen/logrus"
+	"github.com/docker/docker/pkg/stringid"
 	"github.com/docker/docker/pkg/units"
 	"github.com/docker/swarm/cluster"
 	"github.com/docker/swarm/discovery"
@@ -80,16 +81,29 @@ func (c *Cluster) RegisterEventHandler(h cluster.EventHandler) error {
 	return nil
 }
 
+// Generate a globally (across the cluster) unique ID.
+func (c *Cluster) generateUniqueID() string {
+	for {
+		id := stringid.GenerateRandomID()
+		if c.Container(id) == nil {
+			return id
+		}
+	}
+}
+
 // CreateContainer aka schedule a brand new container into the cluster.
 func (c *Cluster) CreateContainer(config *cluster.ContainerConfig, name string) (*cluster.Container, error) {
 	c.scheduler.Lock()
 	defer c.scheduler.Unlock()
 
-	// check new name whether avaliable
+	// Ensure the name is avaliable
 	if cID := c.getIDFromName(name); cID != "" {
 		return nil, fmt.Errorf("Conflict, The name %s is already assigned to %s. You have to delete (or rename) that container to be able to assign %s to a container again.", name, cID, name)
 	}
 
+	// Associate a Swarm ID to the container we are creating.
+	config.SetSwarmID(c.generateUniqueID())
+
 	n, err := c.scheduler.SelectNodeForContainer(c.listNodes(), config)
 	if err != nil {
 		return nil, err

cluster/swarm/cluster_test.go

@@ -8,13 +8,14 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func createEngine(t *testing.T, ID string, containers ...dockerclient.Container) *cluster.Engine {
+func createEngine(t *testing.T, ID string, containers ...*cluster.Container) *cluster.Engine {
 	engine := cluster.NewEngine(ID, 0)
 	engine.Name = ID
 	engine.ID = ID
 
 	for _, container := range containers {
-		engine.AddContainer(&cluster.Container{Container: container, Engine: engine})
+		container.Engine = engine
+		engine.AddContainer(container)
 	}
 
 	return engine
@@ -24,9 +25,16 @@ func TestContainerLookup(t *testing.T) {
 	c := &Cluster{
 		engines: make(map[string]*cluster.Engine),
 	}
-	container := dockerclient.Container{
+	container := &cluster.Container{
-		Id:    "container-id",
+		Container: dockerclient.Container{
-		Names: []string{"/container-name1", "/container-name2"},
+			Id:    "container-id",
+			Names: []string{"/container-name1", "/container-name2"},
+		},
+		Config: cluster.BuildContainerConfig(dockerclient.ContainerConfig{
+			Labels: map[string]string{
+				"com.docker.swarm.id": "swarm-id",
+			},
+		}),
 	}
 
 	n := createEngine(t, "test-engine", container)
@@ -45,4 +53,8 @@ func TestContainerLookup(t *testing.T) {
 	// Container engine/name matching.
 	assert.NotNil(t, c.Container("test-engine/container-name1"))
 	assert.NotNil(t, c.Container("test-engine/container-name2"))
+	// Swarm ID lookup.
+	assert.NotNil(t, c.Container("swarm-id"))
+	// Swarm ID prefix lookup.
+	assert.NotNil(t, c.Container("swarm-"))
 }

test/integration/swarm_id.bats

@@ -0,0 +1,31 @@
+#!/usr/bin/env bats
+
+load helpers
+
+function teardown() {
+	swarm_manage_cleanup
+	stop_docker
+}
+
+@test "swarm id generation" {
+	start_docker_with_busybox 2
+	swarm_manage
+
+	# Create a dummy container just so we interfere with the tests.
+	# This one won't be used.
+	docker_swarm run -d busybox true
+
+	# Create a container and get its Swarm ID back.
+	id=$(docker_swarm run -d busybox true)
+	swarm_id=$(docker_swarm inspect -f '{{ index .Config.Labels "com.docker.swarm.id" }}' "$id")
+
+	# Make sure we got a valid Swarm ID.
+	[[ "${#swarm_id}" -eq 64 ]]
+	[[ "$id" != "$swarm_id" ]]
+
+	# API operations should work with Swarm IDs as well as Container IDs.
+	[[ $(docker_swarm inspect -f "{{ .Id }}" "$swarm_id") == "$id" ]]
+
+	# `docker ps` should be able to filter by Swarm ID using the label.
+	[[ $(docker_swarm ps -a -q --no-trunc --filter="label=com.docker.swarm.id=$swarm_id") == "$id" ]]
+}