CodeParkECS (Elastic Container Service) runs containers on AWS. It has four main ideas.
A cluster is a logical group of compute capacity where tasks run. The capacity is either EC2 instances you register, or Fargate (AWS runs the servers for you).
A task definition is a versioned blueprint. Think of it as a richer Docker Compose file. It lists:
- the containers and their images
- CPU and memory
- ports
- environment variables and secrets
- log settings
- the task role and the execution role
A task is one running copy of a task definition. It is one or more containers that are scheduled together.
A service keeps a desired number of tasks running. It:
- replaces tasks that stop or fail health checks
- registers tasks with a load balancer target group
- does rolling deployments when you update the task definition
- can scale the task count with Application Auto Scaling
One-off jobs, like a database migration, run as standalone tasks without a service.
- A cluster is where tasks run, on EC2 or Fargate capacity.
- A task definition is a versioned blueprint of containers, resources and roles.
- A task is one running copy of a task definition.
- A service keeps N tasks running, works with load balancers, and handles deploys and scaling.
- Standalone tasks suit one-off jobs, like a migration.
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