Refactor: fix name of networkAliasExists vairable, for better readabi…

…lity

README.md

@@ -257,6 +257,8 @@ additional details on each available environment variable.
 | `ECS_DYNAMIC_HOST_PORT_RANGE` | `100-200` | This specifies the dynamic host port range that the agent uses to assign host ports from, for container ports mapping. If there are no available ports in the range for containers, including customer containers and Service Connect Agent containers (if Service Connect is enabled), service deployments would fail. | Defined by `/proc/sys/net/ipv4/ip_local_port_range` | `49152-65535` |
 | `ECS_TASK_PIDS_LIMIT` | `100` | Specifies the per-task pids limit cgroup setting for each task launched on the container instance. This setting maps to the pids.max cgroup setting at the ECS task level. See https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#pid. If unset, pids will be unlimited. Min value is 1 and max value is 4194304 (4*1024*1024) | `unset` | Not Supported on Windows |
 | `ECS_EBSTA_SUPPORTED` | `true` | Whether to use the container instance with EBS Task Attach support. This variable is set properly by ecs-init. Its value indicates if correct environment to support EBS volumes by instance has been set up or not. ECS only schedules EBSTA tasks if this feature is supported by the platform type. Check [EBS Volume considerations](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/ebs-volumes.html#ebs-volume-considerations) for other EBS support details | `true` | Not Supported on Windows |
+|`ECS_OVERRIDE_BRIDGE_NETWORK_NAME` | `ecs` | This value specifies a docker network name used for cotnainers scheduled with a bridge type | `` | `` |
+|`ECS_ADD_CONTAINER_NAME_AS_NETWORK_ALIAS` | `true` | This value tell ECS agent to assign a container name as docker network alias name - it can be used only in a custom docker networks, so only when  `ECS_OVERRIDE_BRIDGE_NETWORK_NAME` is non-empty | `true` | `true` |
 
 Additionally, the following environment variable(s) can be used to configure the behavior of the ecs-init service. When using ECS-Init, all env variables, including the ECS Agent variables above, are read from path `/etc/ecs/ecs.config`:
 | Environment Variable Name | Example Value(s)            | Description | Default value |

agent/config/config.go

@@ -603,6 +603,8 @@ func environmentConfig() (Config, error) {
 		WarmPoolsSupport:                    parseBooleanDefaultFalseConfig("ECS_WARM_POOLS_CHECK"),
 		DynamicHostPortRange:                parseDynamicHostPortRange("ECS_DYNAMIC_HOST_PORT_RANGE"),
 		TaskPidsLimit:                       parseTaskPidsLimit(),
+		OverrideBridgeNetworkName:           os.Getenv("ECS_OVERRIDE_BRIDGE_NETWORK_NAME"),
+		AddContainerNameAsNetworkAlias:      parseBooleanDefaultTrueConfig("ECS_ADD_CONTAINER_NAME_AS_NETWORK_ALIAS"),
 	}, err
 }
 

agent/config/types.go

@@ -394,4 +394,9 @@ type Config struct {
 
 	// NodeUnstageTimeout is the amount of time to wait for unstaging an EBS TA volume
 	NodeUnstageTimeout time.Duration
+	// OverrideBridgeNetworkName is a custom bridge name used for docker container - it has to be created before an agent start
+	OverrideBridgeNetworkName string `trim:"true"`
+
+	// AddContainerNameAsNetworkAlias specifies whether container name should be added as network alias
+	AddContainerNameAsNetworkAlias BooleanDefaultTrue
 }

agent/dockerclient/dockerapi/docker_client.go

@@ -71,6 +71,8 @@ const (
 	dockerContainerDieEvent = "die"
 	// dockerContainerEventExitCodeAttribute is the attribute name to get exit code from Docker event attribute.
 	dockerContainerEventExitCodeAttribute = "exitCode"
+	// NetworkAliasDockerLabel is a nanme of docker label to set a network alias value
+	NetworkAliasDockerLabel = "com.amazonaws.ecs.network-alias"
 )
 
 // Timelimits for docker operations enforced above docker
@@ -715,7 +717,20 @@ func (dg *dockerGoClient) createContainer(ctx context.Context,
 		return DockerContainerMetadata{Error: CannotGetDockerClientError{version: dg.version, err: err}}
 	}
 
-	dockerContainer, err := client.ContainerCreate(ctx, config, hostConfig, &network.NetworkingConfig{}, nil, name)
+	networkConfig := network.NetworkingConfig{
+		EndpointsConfig: make(map[string]*network.EndpointSettings),
+	}
+
+	if config.Labels != nil { // This can happen only in tests
+		networkAliasName, networkAliasExists := config.Labels[NetworkAliasDockerLabel]
+		if networkAliasExists && hostConfig.NetworkMode.IsUserDefined() {
+			networkConfig.EndpointsConfig[hostConfig.NetworkMode.UserDefined()] = &network.EndpointSettings{
+				Aliases: []string{networkAliasName},
+			}
+		}
+	}
+
+	dockerContainer, err := client.ContainerCreate(ctx, config, hostConfig, &networkConfig, nil, name)
 	if err != nil {
 		return DockerContainerMetadata{Error: CannotCreateContainerError{err}}
 	}

agent/dockerclient/dockerapi/docker_client_test.go

@@ -574,8 +574,10 @@ func TestCreateContainerTimeout(t *testing.T) {
 	wait := &sync.WaitGroup{}
 	wait.Add(1)
 	hostConfig := &dockercontainer.HostConfig{Resources: dockercontainer.Resources{Memory: 100}}
-	mockDockerSDK.EXPECT().ContainerCreate(gomock.Any(), &dockercontainer.Config{}, hostConfig,
-		&network.NetworkingConfig{}, gomock.Any(), "containerName").Do(func(u, v, w, x, y, z interface{}) {
+	networkConfig := &network.NetworkingConfig{EndpointsConfig: make(map[string]*network.EndpointSettings)}
+
+	mockDockerSDK.EXPECT().ContainerCreate(gomock.Any(), &dockercontainer.Config{}, hostConfig, networkConfig,
+		gomock.Any(), "containerName").Do(func(u, v, w, x, y, z interface{}) {
 		wait.Wait()
 	}).MaxTimes(1).Return(dockercontainer.CreateResponse{}, errors.New("test error"))
 	ctx, cancel := context.WithCancel(context.TODO())
@@ -592,6 +594,8 @@ func TestCreateContainer(t *testing.T) {
 
 	name := "containerName"
 	hostConfig := &dockercontainer.HostConfig{Resources: dockercontainer.Resources{Memory: 100}}
+	dockerContainerConfig := &dockercontainer.Config{}
+
 	gomock.InOrder(
 		mockDockerSDK.EXPECT().ContainerCreate(gomock.Any(), gomock.Any(), hostConfig, gomock.Any(), gomock.Any(), name).
 			Do(func(u, v, actualHostConfig, x, y, actualName interface{}) {
@@ -609,7 +613,7 @@ func TestCreateContainer(t *testing.T) {
 	)
 	ctx, cancel := context.WithCancel(context.TODO())
 	defer cancel()
-	metadata := client.CreateContainer(ctx, nil, hostConfig, name, defaultTestConfig().ContainerCreateTimeout)
+	metadata := client.CreateContainer(ctx, dockerContainerConfig, hostConfig, name, defaultTestConfig().ContainerCreateTimeout)
 	assert.NoError(t, metadata.Error)
 	assert.Equal(t, "id", metadata.DockerID)
 	assert.Nil(t, metadata.ExitCode, "Expected a created container to not have an exit code")

agent/engine/docker_task_engine.go

@@ -2016,6 +2016,18 @@ func (engine *DockerTaskEngine) createContainer(task *apitask.Task, container *a
 	config.Labels[labelTaskDefinitionVersion] = task.Version
 	config.Labels[labelCluster] = engine.cfg.Cluster
 
+	if task.IsNetworkModeBridge() && engine.cfg.OverrideBridgeNetworkName != "" {
+		logger.Info("Assigning docker container to a custom network", logger.Fields{
+			field.TaskID:    task.GetID(),
+			field.Container: container.Name,
+			"network":       engine.cfg.OverrideBridgeNetworkName,
+		})
+		hostConfig.NetworkMode = dockercontainer.NetworkMode(engine.cfg.OverrideBridgeNetworkName)
+		if engine.cfg.AddContainerNameAsNetworkAlias.Enabled() {
+			config.Labels[dockerapi.NetworkAliasDockerLabel] = container.Name
+		}
+	}
+
 	if dockerContainerName == "" {
 		// only alphanumeric and hyphen characters are allowed
 		reInvalidChars := regexp.MustCompile("[^A-Za-z0-9-]+")