Docker Volumes

When using Docker volumes, the built-in local driver or a third-party volume driver can be used. If a third-party driver is used, it should be installed on the container instance before the task is launched. Docker volumes are managed by Docker and a directory is created in /var/lib/docker/volumes on the container instance that contains the volume data. Docker volumes are only supported when using the EC2 launch type. Windows containers only support the use of the local driver. To use Docker volumes, specify a dockerVolumeConfiguration in your task definition. For more information, see Using volumes.

Some common use cases for Docker volumes are:

To provide persistent data volumes for use with containers
To share a defined data volume at different locations on different containers on the same container instance
To define an empty, nonpersistent data volume and mount it on multiple containers within the same task
To provide a data volume to your task that is managed by a third party driver

Specifying a Docker volume in your Task Definition

Before your containers can use data volumes, you must specify the volume and mount point configurations in your task definition. This section describes the volume configuration for a container. For tasks that use a Docker volume, specify a dockerVolumeConfiguration. For tasks that use a bind mount host volume, specify a host and optional sourcePath.

The task definition JSON shown below shows the syntax for the volumes and mountPoints objects for a container.


{
    "containerDefinitions": [
        {
            "mountPoints": [
                {
                    "sourceVolume": "string",
                    "containerPath": "/path/to/mount_volume",
                    "readOnly": boolean
                }
            ]
        }
    ],
    "volumes": [
        {
            "name": "string",
            "host": {
                "sourcePath": "string"
            },
            "dockerVolumeConfiguration": {
                "scope": "string",
                "autoprovision": boolean,
                "driver": "string",
                "driverOpts": {
                    "key": "value"
                },
                "labels": {
                    "key": "value"
                }
            }
        }
    ]
}

name

Type: String

Required: No

The name of the volume. Up to 255 letters (uppercase and lowercase), numbers, hyphens, and underscores are allowed. This name is referenced in the sourceVolume parameter of container definition mountPoints.

dockerVolumeConfiguration

Type: Object

Required: No

This parameter is specified when using Docker volumes. Docker volumes are only supported when using the EC2 launch type. Windows containers only support the use of the local driver. To use bind mounts, specify a host instead.

scope

Type: String

Valid Values: task | shared

Required: No

The scope for the Docker volume, which determines its lifecycle. Docker volumes that are scoped to a task are automatically provisioned when the task starts and destroyed when the task stops. Docker volumes that are scoped as shared persist after the task stops.

autoprovision

Type: Boolean

Default value: false

Required: No

If this value is true, the Docker volume is created if it does not already exist.

Note

This field is only used if the scope is shared.

driver

Type: String

Required: No

The Docker volume driver to use. The driver value must match the driver name provided by Docker because it is used for task placement. If the driver was installed using the Docker plugin CLI, use docker plugin ls to retrieve the driver name from your container instance. If the driver was installed using another method, use Docker plugin discovery to retrieve the driver name. For more information, see Docker plugin discovery. This parameter maps to Driver in the Create a volume section of the Docker Remote API and the --driver option to docker volume create.

driverOpts

Type: String

Required: No

A map of Docker driver specific options to pass through. This parameter maps to DriverOpts in the Create a volume section of the Docker Remote API and the --opt option to docker volume create.

labels

Type: String

Required: No

Custom metadata to add to your Docker volume. This parameter maps to Labels in the Create a volume section of the Docker Remote API and the --label option to docker volume create.

mountPoints

Type: Object

Required: No

The mount points for data volumes in your container.

This parameter maps to Volumes in the Create a container section of the Docker Remote API and the --volume option to docker run.

Windows containers can mount whole directories on the same drive as $env:ProgramData. Windows containers cannot mount directories on a different drive, and mount point cannot be across drives.

sourceVolume

Type: String

Required: Yes, when mountPoints are used

The name of the volume to mount.

containerPath

Type: String

Required: Yes, when mountPoints are used

The path on the container to mount the volume at.

readOnly

Type: Boolean

Required: No

If this value is true, the container has read-only access to the volume. If this value is false, then the container can write to the volume. The default value is false.

Examples

To provide nonpersistent storage for a container using a Docker volume

In this example, you want a container to use an empty data volume that you aren't interested in keeping after the task has finished. For example, you may have a container that need to access some scratch file storage location during a task. This task can be achieved using either a Docker volume.

In the task definition volumes section, define a data volume with name and DockerVolumeConfiguration values. In this example, we specify the scope as task so the volume will deleted once the task stops, set autoprovision to true so the volume will be created for us, and use the built-in local driver.
```
"volumes": [
    {
        "name": "scratch",
        "dockerVolumeConfiguration" : {
            "scope": "task",
            "autoprovision": true,
            "driver": "local",
            "labels": {
                "scratch: space"
            }
        }
    }
]
```
In the containerDefinitions section, define a container with mountPoints that reference the name of the defined volume and the containerPath value to mount the volume at on the container.
```
"containerDefinitions": [
    {
        "name": "container-1",
        "mountPoints": [
            {
              "sourceVolume": "scratch",
              "containerPath": "/var/scratch"
            }
        ]
    }
]
```

To provide persistent storage for a container using a Docker volume

In this example, you want a shared volume for multiple containers to use and you want it to persist after any single task using it has stopped. The built-in local driver is being used so the volume will still be tied to the lifecycle of the container instance.

In the task definition volumes section, define a data volume with name and DockerVolumeConfiguration values. In this example, we will specify a shared scope so the volume will persist, set autoprovision to true so the volume will be created for us, and use the built-in local driver.
```
"volumes": [
    {
        "name": "database",
        "dockerVolumeConfiguration" : {
            "scope": "shared",
            "autoprovision": true,
            "driver": "local",
            "labels": {
                "database: database_name"
            }
        }
    }
]
```

In the containerDefinitions section, define a container with mountPoints that reference the name of the defined volume and the containerPath value to mount the volume at on the container.


"containerDefinitions": [
    {
        "name": "container-1",
        "mountPoints": [
        {
          "sourceVolume": "database",
          "containerPath": "/var/database"
        }
      ]
    },
    {
      "name": "container-2",
      "mountPoints": [
        {
          "sourceVolume": "database",
          "containerPath": "/var/database"
        }
      ]
    }
  ]

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