Example for Fargate Task Defintion with ECR Docker Image Asset - https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-ecr-assets.DockerImageAsset.html

docker-image-asset.ts

import ecs = require('@aws-cdk/aws-ecs');
import { DockerImageAsset } from '@aws-cdk/aws-ecr-assets';
import path = require('path')

export interface FooFargateProps {  
}

export class FooFargate extends cdk.Construct {
  constructor(scope: cdk.Construct, id: string, props: FooFargateProps = {}) {
    super(scope, id);

    const taskDefinition = new ecs.FargateTaskDefinition(this, 'FooDefinition', {
      memoryLimitMiB: 2048,
      cpu: 1024    
    });

    const asset = new DockerImageAsset(this, 'FooEcrImage', {
      directory: path.join(__dirname, 'assets'),
    });
    
    asset.repository.grantPull(taskDefinition.taskRole)

    const logging = new ecs.AwsLogDriver({
      streamPrefix: "foo"
    })
    
    taskDefinition.addContainer('DefaultContainer', {
      image: ecs.ContainerImage.fromEcrRepository(asset.repository),
      memoryReservationMiB: 2048,
      cpu: 1024,
      logging
    });
  }
}