# Job definitions on Amazon ECS Managed Instances
<a name="ecs-managed-instances-job-definitions"></a>

AWS Batch jobs on Amazon ECS Managed Instances use the `ecsProperties` job definition format with a platform capability of `MANAGED_INSTANCES`. Amazon ECS Managed Instances jobs do not support legacy `containerProperties`.

The following list describes job definition parameters that are specific to or restricted for Amazon ECS Managed Instances jobs.

`platformCapabilities`  
Must be specified as `MANAGED_INSTANCES`.  

```
"platformCapabilities": [ "MANAGED_INSTANCES" ]
```

`type`  
Must be specified as `container`.  

```
"type": "container"
```

Parameters in `ecsProperties`    
`networkMode`  
Controls how the task's network is configured. This parameter only applies to Amazon ECS Managed Instances job definitions. This parameter does not apply to Fargate or Amazon EC2 platform job definitions.  
Valid values: `host`  
When not specified, the default is `host`. With `host` mode, the container shares the host instance's network stack directly, providing maximum network bandwidth.  

```
"networkMode": "host"
```  
`runtimePlatform`  
Specifies the operating system family and CPU architecture for the task. Use this to run jobs on ARM64 (Graviton) instances. The valid value for `operatingSystemFamily` is `LINUX` (default). The valid values for `cpuArchitecture` are `X86_64` and `ARM64`.  

```
"runtimePlatform": {
  "operatingSystemFamily": "LINUX",
  "cpuArchitecture": "ARM64"
}
```  
`executionRoleArn`  
The IAM role that grants the Amazon ECS container agent permission to make AWS API calls on your behalf, such as pulling container images from Amazon ECR. For more information, see [IAM Roles for Tasks](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task_execution_IAM_role.html) in the *Amazon Elastic Container Service Developer Guide*.

`resourceRequirements`  
Both memory and vCPU requirements must be specified in `resourceRequirements`. Unlike Fargate, Amazon ECS Managed Instances does not restrict which vCPU and memory combinations are valid — you can specify any values that fit within the instance types available to your compute environment. GPU resources are supported.  

```
"resourceRequirements": [
  {"type": "MEMORY", "value": "8192"},
  {"type": "VCPU", "value": "4"},
  {"type": "GPU", "value": "1"}
]
```

Parameters supported on Amazon ECS Managed Instances but not Fargate  
The following parameters are available for Amazon ECS Managed Instances jobs but are blocked for Fargate:  
+ `privileged` — run the container with elevated privileges on the host instance.
+ `resourceRequirements` type `GPU` — request NVIDIA GPU devices.
+ `linuxParameters.devices` — expose host devices to the container.
+ `linuxParameters.tmpfs` — mount RAM-backed tmpfs filesystems.
+ `ulimits` — set resource limits (nofile, nproc, etc.) on the container.
+ `volumes` with `host.sourcePath` — bind mount host paths into the container.

Parameters not supported on Amazon ECS Managed Instances    
`fargatePlatformConfiguration`  
Not applicable for Amazon ECS Managed Instances jobs.  
Multi-node parallel (MNP) jobs  
Amazon ECS Managed Instances does not support multi-node parallel jobs. Use Amazon EC2 managed compute environments for MNP workloads.

Parameters in `logConfiguration`    
`logDriver`  
Only `awslogs`, `splunk`, and `awsfirelens` are supported for Amazon ECS Managed Instances jobs.