# Submit a job requiring limits
<a name="job-limit-job"></a>

You apply a limit by specifying it as a host requirement for the job or job step. If you don't specify a limit in a step and that step uses an associated resource, the step's usage isn't counted against the limit when jobs are scheduled..

Some Deadline Cloud submitters enable you to set a host requirement. You can specify the limit's amount requirement name in the submitter to apply the limit.

If your submitter doesn't support adding host requirements, you can also apply a limit by editing the job template for the job.

**To apply a limit to a job step in the job bundle**

1. Open the job template for the job using a text editor. The job template is located in the job bundle directory for the job. For more information, see [Job bundles](https://docs.aws.amazon.com/deadline-cloud/latest/developerguide/build-job-bundle.html) in the *Deadline Cloud Developer Guide*.

1. Find the step definition for the step to apply the limit to.

1. Add the following to the step definition. Replace {{amount.name}} with the amount requirement name of your limit. For typical use, you should set the `min` value to 1.

------
#### [ YAML ]

   ```
     hostRequirements:
       amounts:
       - name: amount.{{name}}
         min: 1
   ```

------
#### [ JSON ]

   ```
   "hostRequirements": {
       "amounts": [
           {
               "name": "{{amount.name}}",
               "min": "1"
           }
       }
   }
   ```

------

   You can add multiple limits to a job step as follows. Replace {{amount.name\_1}} and {{amount.name\_2}} with the amount requirement names of your limits.

------
#### [ YAML ]

   ```
     hostRequirements:
       amounts:
       - name: {{amount.name_1}}
         min: 1
       - name: {{amount.name_2}}
         min: 1
   ```

------
#### [ JSON ]

   ```
   "hostRequirements": {
       "amounts": [
           {
               "name": "amount.{{name_1}}",
               "min": "1"
           },
           {
               "name": "amount.{{name_2}}",
               "min": "1"
           }
       }
   }
   ```

------

1. Save the changes to the job template.

## Automate limits with submission hooks
<a name="job-limit-hooks"></a>

If you want to enforce limits across all job submissions without requiring artists to manually edit job templates, you can use a [pre-submission hook](https://github.com/aws-deadline/deadline-cloud/blob/mainline/docs/submission-hooks.md) to automatically inject the host requirement into every job template at submission time.

A pre-submission hook is a script that runs before the job is submitted. The hook can modify the job bundle's `template.yaml` to add the `hostRequirements` amounts entry for your limit. This approach ensures that every job submitted through the Deadline Cloud CLI or DCC submitters declares its need for the limited resource.

For a complete working example, see the [license limits submission hook sample](https://github.com/aws-deadline/deadline-cloud-samples/tree/mainline/submission_hooks/license_limits) in the Deadline Cloud samples repository.

## End-to-end example: Enforce V-Ray license limits
<a name="job-limit-example"></a>

This example shows how to set up a limit for 5 V-Ray floating licenses and verify that the scheduler enforces it.

**To set up and test a V-Ray license limit**

1. Create the limit on your farm:

   ```
   aws deadline create-limit \
       --farm-id {{farm-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX}} \
       --display-name "VRay License" \
       --amount-requirement-name "amount.vray" \
       --max-count 5
   ```

1. Associate the limit with your queue:

   ```
   aws deadline create-queue-limit-association \
       --farm-id {{farm-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX}} \
       --queue-id {{queue-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX}} \
       --limit-id {{limit-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX}}
   ```

1. Add the host requirement to your job template:

   ```
   specificationVersion: jobtemplate-2023-09
   name: My VRay Render
   steps:
     - name: Render
       hostRequirements:
         amounts:
           - name: amount.vray
             min: 1
       script:
         actions:
           onRun:
             command: vray
             args: ["-scene", "{{Param.SceneFile}}"]
   ```

1. Submit the job. The scheduler allows at most 5 tasks with `amount.vray` to run concurrently across all jobs in the queue. Additional tasks remain in the `READY` state until a slot becomes available.

To verify the limit is working, temporarily set `maxCount` to 1 and submit two jobs. The first job runs while the second remains in the `READY` state until the first completes.