Schedule your containers on Amazon ECS

Amazon Elastic Container Service (Amazon ECS) is a shared state, optimistic concurrency system that provides flexible scheduling capabilities for your containerized workloads. The Amazon ECS schedulers use the same cluster state information as the Amazon ECS API to make appropriate placement decisions.

Amazon ECS provides a service scheduler for long-running tasks and applications. It also provides the ability to run standalone tasks or scheduled tasks for batch jobs or single run tasks. You can specify the task placement strategies and constraints for running tasks that best meet your needs. For example, you can specify whether tasks run across multiple Availability Zones or within a single Availability Zone. And, optionally, you can integrate tasks with your own custom or third-party schedulers.

Option	When to use	More information
Service	The service scheduler is suitable for long running stateless services and applications. The service scheduler optionally also makes sure that tasks are registered against an Elastic Load Balancing load balancer. You can update your services that are maintained by the service scheduler. This might include deploying a new task definition or changing the number of desired tasks that are running. By default, the service scheduler spreads tasks across multiple Availability Zones. However, you can use task placement strategies and constraints to customize task placement decisions.	Amazon ECS services
Standalone task	A standalone task is suitable for processes such as batch jobs that perform work and then stop. For example, you can have a process call RunTask when work comes into a queue. The task pulls work from the queue, performs the work, and then exits. Using RunTask, you can allow the default task placement strategy to distribute tasks randomly across your cluster. This minimizes the chances that a single instance gets a disproportionate number of tasks.	Amazon ECS standalone tasks
Scheduled tasks	A scheduled task is suitable when you have tasks to run at set intervals in your cluster, you can use EventBridge Scheduler to create a schedule. You can run tasks for a backup operation or a log scan. The EventBridge Scheduler schedule that you create can run one or more tasks in your cluster at specified times. Your scheduled event can be set to a specific interval (run every N minutes, hours, or days). Otherwise, for more complicated scheduling, you can use a cron expression.	Using Amazon EventBridge Scheduler to schedule Amazon ECS tasks

Compute options

With Amazon ECS, you can specify the infrastructure your tasks or services run on. You can use a capacity provider strategy, or a launch type.

For Fargate, the capacity providers are Fargate and Fargate Spot. For EC2, the capacity provider is the Auto Scaling group with the registered container instances.

The capacity provider strategy distributes your tasks across the capacity providers associated with your cluster.

Only capacity providers that are both already associated with a cluster and have an ACTIVE or UPDATING status can be used in a capacity provider strategy. You can associate a capacity provider with a cluster when you create a cluster.

In a capacity provider strategy, the optional base value designates how many tasks, at a minimum, run on a specified capacity provider. Only one capacity provider in a capacity provider strategy can have a base defined.

The weight value determines the relative percentage of the total number of launched tasks that use the specified capacity provider. Consider the following example. You have a strategy that contains two capacity providers, and both have a weight of 1. When the base percentage is reached, the tasks are split evenly across the two capacity providers. Using that same logic, suppose that you specify a weight of 1 for capacityProviderA and a weight of 4 for capacityProviderB. Then, for every one task that's run using capacityProviderA, there are four tasks that use capacityProviderB.

The launch type launches your tasks directly on either Fargate or on the Amazon EC2 instances that you have manually registered to your clusters.