# Specify a Docker volume in an Amazon ECS task definition
<a name="specify-volume-config"></a>

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 following task definition JSON 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",
            "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 the container definition `mountPoints` object.

`dockerVolumeConfiguration`  
Type: [DockerVolumeConfiguration](https://docs.aws.amazon.com/AmazonECS/latest/APIReference/API_DockerVolumeConfiguration.html) Object  
Required: No  
This parameter is specified when using Docker volumes. Docker volumes are supported only when running tasks on EC2 instances. Windows containers support only the use of the `local` driver. To use bind mounts, specify a `host` instead.    
`scope`  
Type: String  
Valid Values: `task` \$1 `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 doesn't already exist. This field is used only if the `scope` is `shared`. If the `scope` is `task`, then this parameter must be omitted.  
`driver`  
Type: String  
Required: No  
The Docker volume driver to use. The driver value must match the driver name provided by Docker because this name is used for task placement. If the driver was installed by using the Docker plugin CLI, use `docker plugin ls` to retrieve the driver name from your container instance. If the driver was installed by using another method, use Docker plugin discovery to retrieve the driver name.  
`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 Docker.  
`labels`  
Type: String  
Required: No  
Custom metadata to add to your Docker volume.

`mountPoints`  
Type: Object array  
Required: No  
The mount points for the data volumes in your container. This parameter maps to `Volumes` in the create-container Docker 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 points cannot be used across drives. You must specify mount points to attach an Amazon EBS volume directly to an Amazon ECS task.    
`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 in the container where the volume will be mounted.  
`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`.  
For tasks that run on EC2 instances running the Windows operating system, leave the value as the default of `false`.