How to override resourceRequirements with aws_cloudwatch_event_target?

Question

I have a AWS Batch Job defined in Terraform and working fine in AWS. I am creating several override rules with `cronExpression()` so the job is invoked at specific times.
I am using `aws_cloudwatch_event_target` and `aws_cloudwatch_event_rule`. Most of the functionality works. I am the rule triggers with the right, name, arn, etc. even the right command.
My TF code looks like:
```terraform
resource "aws_cloudwatch_event_rule" "batchjob" {
  name       = "foo"
  is_enabled = true
  # runs on the first of every month at 15:00 UTC 
  # https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/ScheduledEvents.html
  schedule_expression = "cron(0 15 1 * ? *)"
}

resource "aws_cloudwatch_event_target" "batchjob_target" {
  rule     = "foo"
  arn      = ""
  role_arn = ""
  input = jsonencode({
    # https://docs.aws.amazon.com/batch/latest/APIReference/API_ContainerOverrides.html
    "ContainerOverrides" : {
      "Command" : [
        "/bin/java",
        "-jar",
        "/batch-jobs.jar",
        "foobar"
      ],
      # VCPU and MEMORY are linked: https://docs.aws.amazon.com/batch/latest/APIReference/API_ResourceRequirement.html
      # https://repost.aws/questions/QUP1kkGbDrT1uC4jTW6DXZ4A/set-cpu-and-memory-requirements-for-a-fargate-aws-batch-job-from-an-aws-cloudwatch-event
      "ResourceRequirements" : [
        {
          "Type"  = "VCPU"
          "Value" = "4"
        },
        {
          "Type"  = "MEMORY"
          "Value" = "8192"
        }
      ]
    }
    }
  )
}
batch_target {
  job_name       = "foo"
  job_definition = aws_batch_job_definition.job_definition.arn
}

```

I have confirmed that `ContainerOverrides` and `Command` must be _pascal_ case for it work. If I use _camel_ case, it doesn't see the overrides.

I was able to get it to work vai the AWS CLI with the following command:
```shell
AWS_PROFILE=dev aws batch submit-job \
        --job-name "foobar" \
        --job-queue "arn:aws:batch:us-west-2:" \
        --job-definition "arn:aws:batch:us-west-2:" \
        --container-overrides '{"command": ["/bin/java","-jar","/batch-jobs.jar","foobar"], "resourceRequirements": [{"value": "4", "type": "VCPU"}, {"value": "8192", "type": "MEMORY"}]}'
```

But I cannot figure out the proper syntax, in terraform to override the resource requirements. What am I missing?

Justin_B · Accepted Answer

Hi Eric, thanks for reaching out!

Looking in to this, I was able to confirm internally that the ResourceRequirement parameters under ContainerOverrides are not processed when configuring a Batch Job as an EventBridge rule target. The parameters under Command will be accepted, but ResourceRequirements do not get passed from the EventBridge Target to the Batch Job. I can also confirm that there is a Feature Request in place to allow for this, but I'm unable to provide an ETA on when this may be available.

However, I can recommend that instead of using an EventBridge rule with a cron expression, you can accomplish your use case using the newer [EventBridge Scheduler feature](https://docs.aws.amazon.com/eventbridge/latest/userguide/scheduler.html). This feature has [TerraForm support](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/scheduler_schedule) and will allow you to schedule direct Batch SubmitJob calls with all the parameters you wish to pass, including Container Override parameters with ResourceRequirement fields.

I tested this feature with VCPU and MEMORY ResourceRequirements with a Scheduler schedule in the console and passed the following JSON for the API call:

```
{
	"JobDefinition": "arn:aws:batch:us-west-1:123456789012:",
	"JobName": "MyData",
	"JobQueue": "arn:aws:batch:us-west-1:123456789012:",
	"ContainerOverrides": {
		"ResourceRequirements": [{
				"Type": "VCPU",
				"Value": "4"
			},
			{
				"Type": "MEMORY",
				"Value": "8192"
			}
		]
	}
}
```

The job was successfully started using the VCPU and MEMORY requirements specified in my ContainerOverride fields.

I hope this information was helpful!

How to override resourceRequirements with aws_cloudwatch_event_target?

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