essential

If the `essential` parameter of a container is marked as `true`, and that container fails or stops for any reason, all other containers that are part of the task are stopped. If the `essential` parameter of a container is marked as `false`, its failure doesn't affect the rest of the containers in a task. If this parameter is omitted, a container is assumed to be essential. All tasks must have at least one essential container. If you have an application that's composed of multiple containers, group containers that are used for a common purpose into components, and separate the different components into multiple task definitions. For more information, see Application Architecture in the Amazon Elastic Container Service Developer Guide.