Use an externally-managed task definition, rather than one created by Jenkins. Allows you to use a task definition created in the AWS Console, command line, or other tools. Specifying an explicit task definition will override all other task definition options, and will prevent Jenkins from creating or modifying task definitions for this agent. (You should still specify reasonable CPU and memory sizes in Jenkins. The values will not be used by ECS, but will be used by Jenkins to estimate cluster capacity.)

You may specify either a full task definition ARN, a family name, or a family name and revision. If specifying only a family name, Jenkins will use the latest active task definition with that family name. If you enter the full ARN, Jenkins will always use the specified ARN, even if you create later revisions of the task definition. See the DescribeTaskDefinition API documentation for details.

For example, if the task definition you would like to use is in the "hello_world" family, you could enter "hello_world", "hello_world:8", or "arn:aws:ecs:us-east-1:123456789012:task-definition/hello_world:8" as the Task Definition Override.

Important: If your externally-managed task definition contains multiple container definitions (sidecars), the Jenkins agent container must be the first container defined in the task definition.