|cdk| Examples
This topic contains some examples to help you get started using some of the advanced constructs offered by the |cdk|.
- :doc:`ecs_example` walks you through creating a Fargate service running on an ECS cluster fronted by an internet-facing
application load balancer.
- :doc:`apples_example` walks you through creating the resources for a simple widget dispensing service.
.. toctree:: :maxdepth: 2 :hidden: ECS Example <ecs_example> Apples Example <apples_example>
|ECSlong| (|ECS|) is a highly scalable, fast, container management service that makes it easy to run, stop, and manage Docker containers on a cluster. You can host your cluster on infrastructure that is managed by |ECS| by launching your services or tasks using the Fargate launch type. For more control you can host your tasks on a cluster of |EC2long| (|EC2|) instances that you manage by using the EC2 launch type.
This example shows you how to launch some services using the Fargate launch type. If you've ever used the console to create a Fargate service, you know that there are many steps you must follow to accomplish that task. AWS has a number of tutorials and documentation topics that walk you through creating a Fargate service, including:
- How to Deploy Docker Containers - AWS
- Setting up with Amazon ECS and Getting Started with Amazon ECS using Fargate
This example creates a similar Fargate service in |cdk| code.
Since |ECS| can be used with a number of AWS services, you should understand how the |ECS| construct that we use in this example gives you a leg up on using AWS services by providing the following benefits:
Automatically configures a load balancer.
Automatic security group opening for load balancers, which enables load balancers to communicate with instances without you explictly creating a security group.
Automatic ordering dependency between service and load balancer attaching to a target group, where the |cdk| enforces the correct order of creating the listener before an instance is created
Automatic userdata configuration on auto-scaling group, which creates the correct configuration to associate a cluster to AMI(s).
Early validation of parameter combinations, which exposes |CFN| issues earlier, thus saving you deployment time. For example, depending upon the task, it is easy to mis-configure the memory settings. Previously you would not encounter an error until you deployed your app, but now the |cdk| can detect a misconfiguration and emit an error when you synthesize your app.
Automatically adds permissions for |ECR| if you use an image from |ECR| When you use an image from |ECR|, the |cdk| adds the correct permissions.
Convenient API for autoscaling The |cdk| supplies a method so you can autoscale instances when you use an |EC2| cluster; this functionality is done automatically when you use an instance in a Fargate cluster.
In addition, the |cdk| will prevent instances from being deleted when autoscaling tries to kill an instance, but either a task is running or is scheduled on that instance.
Previously, you had to create a Lambda function to have this functionality.
Asset support, so that you can deploy source from your machine to |ECS| in one step Previously, to use application source you had to perform a number of manual steps (upload to |ECR|, create Docker image, etc.).
Step 1: Create the Directory and Initialize the |cdk|
Let's start with creating a new directory to hold our |cdk| code and create a new app in that directory.
mkdir MyEcsConstruct
cd MyEcsConstruct.. tabs::
.. group-tab:: TypeScript
.. code-block:: sh
cdk init --language typescript
Build the app and confirm that it creates an empty stack.
.. code-block:: sh
npm run build
cdk synth
You should see a stack like the following,
where CDK-VERSION is the version of the CDK.
.. code-block:: sh
Resources:
CDKMetadata:
Type: 'AWS::CDK::Metadata'
Properties:
Modules: @aws-cdk/cdk=CDK-VERSION,@aws-cdk/cx-api=CDK-VERSION,my_ecs_construct=0.1.0
Install support for |EC2| and |ECS|.
.. tabs::
.. group-tab:: TypeScript
.. code-block:: sh
npm install @aws-cdk/aws-ec2 @aws-cdk/aws-ecs
There are two different ways of running your container tasks with |ECS|:
- Using the Fargate launch type, where |ECS| manages the physical machines that your containers are running on for you
- Using the EC2 launch type, where you do the managing, such as specifying autoscaling
The following example creates a Fargate service running on an ECS cluster fronted by an internet-facing application load balancer.
.. tabs::
.. group-tab:: TypeScript
Add the following import statements to *lib/my_ecs_construct-stack.ts*:
.. code-block:: typescript
import ec2 = require('@aws-cdk/aws-ec2');
import ecs = require('@aws-cdk/aws-ecs');
Replace the comment at the end of the constructor with the following code:
.. code-block:: typescript
const vpc = new ec2.VpcNetwork(this, 'MyVpc', {
maxAZs: 3 // Default is all AZs in region
});
const cluster = new ecs.Cluster(this, 'MyCluster', {
vpc: vpc
});
// Create a load-balanced Fargate service and make it public
new ecs.LoadBalancedFargateService(this, 'MyFargateService', {
cluster: cluster, // Required
cpu: '512', // Default is 256
desiredCount: 6, // Default is 1
image: ecs.ContainerImage.fromDockerHub('amazon/amazon-ecs-sample'), // Required
memoryMiB: '2048', // Default is 512
publicLoadBalancer: true // Default is false
});
Save it and make sure it builds and creates a stack.
.. code-block:: sh
npm run build
cdk synth
The stack is hundreds of lines, so we won't show it here.
The stack should contain one default instance, a private subnet and a public subnet
for the three availability zones, and a security group.
Deploy the stack.
.. code-block:: sh
cdk deploy
|CFN| displays information about the dozens of steps that
it takes as it deploys your app.
That's how easy it is to create a Fargate service to run a Docker image.