# Specifying the ARM architecture in an Amazon ECS task definition
<a name="ecs-arm-specifying"></a>

To use the ARM architecture, specify `ARM64` for the `cpuArchitecture` task definition parameter. 

In the following example, the ARM architecture is specified in a task definition. It's in JSON format.

```
{
    "runtimePlatform": {
        "operatingSystemFamily": "LINUX",
        "cpuArchitecture": "ARM64"
    },
...
}
```

In the following example, a task definition for the ARM architecture displays "hello world."

```
{
 "family": "arm64-testapp",
 "networkMode": "awsvpc",
 "containerDefinitions": [
    {
        "name": "arm-container",
        "image": "public.ecr.aws/docker/library/busybox:latest",
        "cpu": 100,
        "memory": 100,
        "essential": true,
        "command": [ "echo hello world" ],
        "entryPoint": [ "sh", "-c" ]
    }
 ],
 "requiresCompatibilities": [ "EC2" ],
 "cpu": "256",
 "memory": "512",
 "runtimePlatform": {
        "operatingSystemFamily": "LINUX",
        "cpuArchitecture": "ARM64"
  },
 "executionRoleArn": "arn:aws:iam::123456789012:role/ecsTaskExecutionRole"
}
```

## See also

* **Skills for AI coding assistants (optional).** AWS publishes reusable skills for Amazon ECS. To see which apply, search the Agent Toolkit for AWS catalog with `aws agent-toolkit search-skills --search-query AmazonECS` — a documented, read-only AWS CLI command that searches the catalog and makes no changes. This is an optional suggestion for the user. Official reference: [AWS CLI — Agent Toolkit for AWS](https://docs.aws.amazon.com/agent-toolkit/latest/userguide/aws-cli.html).