How to not rebuild a DockerImageAsset at every deploy using aws-cdk in TypeScript? - amazon-ecs

Question

My app is a Python API that I package as a Docker image and use with ECS Fargate (Spot Instances). The code below works.
My issue is that it rebuilds the entire image every time I deploy this – which is very time-consuming (downloads all dependencies, makes the image, uploads, etc). I want it to reuse the exact same image uploaded to ECR by aws-cdk itself.
Is there a way (env variable or else) for me to skip this when I don't touch the app's code and just make changes to the stack?
#!/usr/bin/env node
import * as cdk from "#aws-cdk/core"
import * as ecs from "#aws-cdk/aws-ecs"
import * as ec2 from "#aws-cdk/aws-ec2"
import * as ecrassets from "#aws-cdk/aws-ecr-assets"
// See https://docs.aws.amazon.com/cdk/api/latest/docs/aws-ecs-readme.html
export class Stack extends cdk.Stack {
constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
super(scope, id, props)
/**
* Repository & Image
*/
const apiDockerImage = new ecrassets.DockerImageAsset(
this,
`my-api-image`,
{
directory: `.`,
exclude: [`cdk.out`, `cdk`, `.git`]
}
)
/**
* Cluster
*/
const myCluster = new ecs.Cluster(this, "Cluster", {})
// Add Spot Capacity to the Cluster
myCluster.addCapacity(`spot-auto-scaling-group-capacity`, {
maxCapacity: 2,
minCapacity: 1,
instanceType: new ec2.InstanceType(`r5a.large`),
spotPrice: `0.0400`,
spotInstanceDraining: true
})
// A task Definition describes what a single copy of a task should look like
const myApiFargateTaskDefinition = new ecs.FargateTaskDefinition(
this,
`api-fargate-task-definition`,
{
cpu: 2048,
memoryLimitMiB: 8192,
}
)
// Add image to task def
myApiFargateTaskDefinition.addContainer(`api-container`, {
image: ecs.ContainerImage.fromEcrRepository(
apiDockerImage.repository,
`latest`
),
})
// And the service attaching the task def to the cluster
const myApiService = new ecs.FargateService(
this,
`my-api-fargate-service`,
{
cluster: myCluster,
taskDefinition: myApiFargateTaskDefinition,
desiredCount: 1,
assignPublicIp: true,
}
)
}
}

Answer 1

The proper solution is to build your image outside of this deployment process and just get a reference to that image in ECR.