Amazon EC2 Container Service (ECS) – Container Management for the AWS Cloud
Earlier this year I wrote about container computing and enumerated some of the benefits that you get when you use it as the basis for a distributed application platform: consistency & fidelity, development efficiency, and operational efficiency. Because containers are lighter in weight and have less memory and computational overhead than virtual machines, they make it easy to support applications that consist of hundreds or thousands of small, isolated “moving parts.” A properly containerized application is easy to scale and maintain, and makes efficient use of available system resources.
Introducing Amazon Amazon EC2 Container Service
In order to help you to realize these benefits, we are announcing a preview of our new container management service, EC2 Container Service (or ECS for short). This service will make it easy for you to run any number of Docker containers across a managed cluster of Amazon Elastic Compute Cloud (EC2) instances using powerful APIs and other tools. You do not have to install cluster management software, purchase and maintain the cluster hardware, or match your hardware inventory to your software needs when you use ECS. You simply launch some instances in a cluster, define some tasks, and start them. ECS is built around a scalable, fault-tolerant, multi-tenant base that takes care of all of the details of cluster management on your behalf.
By the way, don’t let the word “cluster” scare you off! A cluster is simply a pool of compute, storage, and networking resources that serves as a host for one or more containerized applications. In fact, your cluster can even consist of a single t2.micro instance. In general, a single mid-sized EC2 instance has sufficient resources to be used productively as a starter cluster.
EC2 Container Service Benefits
Here’s how this service will help you to build, run, and scale Docker-based applications:
- Easy Cluster Management – ECS sets up and manages clusters made up of Docker containers. It launches and terminates the containers and maintains complete information about the state of your cluster. It can scale to clusters that encompass tens of thousands of containers across multiple Availability Zones.
- High Performance – You can use the containers as application building blocks. You can start, stop, and manage thousands of containers in seconds.
- Flexible Scheduling – ECS includes a built-in scheduler that strives to spread your containers out across your cluster to balance availability and utilization. Because ECS provides you with access to complete state information, you can also build your own scheduler or adapt an existing open source scheduler to use the service’s APIs.
- Extensible & Portable – ECS runs the same Docker daemon that you would run on-premises. You can easily move your on-premises workloads to the AWS cloud, and back.
- Resource Efficiency – A containerized application can make very efficient use of resources. You can choose to run multiple, unrelated containers on the same EC2 instance in order to make good use of all available resources. You could, for example, decide to run a mix of short-term image processing jobs and long-running web services on the same instance.
- AWS Integration – Your applications can make use of AWS features such as Elastic IP addresses, resource tags, and Virtual Private Cloud (VPC). The containers are, in effect, a new base-level building block in the same vein as EC2 and S3.
- Secure – Your tasks run on EC2 instances within an Amazon Virtual Private Cloud. The tasks can take advantage of IAM roles, security groups, and other AWS security features. Containers run in a multi-tenant environment and can communicate with each other only across defined interfaces. The containers are launched on EC2 instances that you own and control.
Using EC2 Container Service
ECS was designed to be easy to set up and to use!
You can launch an ECS-enabled AMI and your instances will be automatically checked into your default cluster. If you want to launch into a different cluster you can specify it by modifying the configuration file in the image, or passing in User Data on launch. To ECS-enable a Linux AMI, you simply install the ECS Agent and the Docker daemon.
ECS will add the newly launched instance to its capacity pool and run containers on it as directed by the scheduler. In other words, you can add capacity to any of your clusters by simply launching additional EC2 instances in them!
The ECS Agent will be available in open source form under an Apache license. You can install it on any of your existing Linux AMIs and call
registerContainerInstances to add them to your cluster.
Here are a few vocabulary items to help you to get familiar with the terminology used by ECS:
- Cluster – A cluster is a pool of EC2 instances in a particular AWS Region, all managed by ECS. One cluster can contain multiple instance types and sizes, and can reside within one or more Availability Zones.
- Scheduler – A scheduler is associated with each cluster. The scheduler is responsible for making good use of the resources in the cluster by assigning containers to instances in a way that respects any placement constraints and simultaneously drives as much parallelism as possible, while also aiming for high availability.
- Container – A container is a packaged (or “Dockerized,” as the cool kids like to say) application component. Each EC2 instance in a cluster can serve as a host to one or more containers.
- Task Definition – A JSON file that defines a Task as a set of containers. Fields in the file define the image for each container, convey memory and CPU requirements, and also specify the port mappings that are needed for the containers in the task to communicate with each other.
- Task – A task is an instantiation of a Task Definition consisting of one or more containers, defined by the work that they do and their relationship to each other.
- ECS-Enabled AMI – An Amazon Machine Image (AMI) that runs the ECS Agent and dockerd. We plan to ECS-enable the Amazon Linux AMI and are working with our partners to similarly enable their AMIs.
EC2 Container Service includes a set of APIs that are both simple and powerful. You can create, describe, and destroy clusters and you can register EC2 instances therein. You can create task definitions and initiate and manage tasks.
Here is the basic set of steps that you will follow in order to run your application on ECS. I am making the assumption that you have already Dockerized your application by breaking it down in to fine-grained components, each described by a
Dockerfile and each running nicely on your existing infrastructure. There are plenty of good resources online to help you with this process. Many popular application components have already been Dockerized and can be found on Docker Hub. You can use ECS with any public or private Docker repository that you can acccess. Ok, so here are the steps:
- Create a cluster, or decide to use the default one for your account in the target Region.
- Create your task definitions and register them with the cluster.
- Launch some EC2 instances and register them with the cluster.
- Start the desired number of copies of each task.
- Monitor the overall utilization of the cluster and the overall throughput of your application, and make adjustments as desired. For example, you can launch and then register additional EC2 instances in order to expand the cluster’s pool of available resources.
EC2 Container Service Pricing and Availability
The service is launch today in preview form. If you are interested in signing up, click here to join the waiting list.
There is no extra charge for ECS. As usual, you pay only for the resources that you use.