update doc

README.md

@@ -2,6 +2,7 @@
 AWS CDK L3 construct that allows you to run a build job for specific purposes. Currently this library supports the following use cases:
 
 * Build web frontend static files
+* Build a container image
 * Build Seekable OCI (SOCI) indices for container images
 
 ## Usage
@@ -118,6 +119,35 @@ To mitigate this issue, you can separate the stack for frontend construct from o
       ],
 ```
 
+### Build a container image
+You can build a container image at deploy time by the following code:
+
+```ts
+import { ContainerImageBuild } from 'deploy-time-build;
+
+const image = new ContainerImageBuild(this, 'Build', { 
+    directory: 'example-image', 
+    buildArgs: { DUMMY_FILE_SIZE_MB: '15' },
+    tag: 'my-image-tag',
+});
+new DockerImageFunction(this, 'Function', {
+    code: image.toLambdaDockerImageCode(),
+});
+const armImage = new ContainerImageBuild(this, 'BuildArm', {
+    directory: 'example-image',
+    platform: Platform.LINUX_ARM64,
+    repository: image.repository,
+    zstdCompression: true,
+});
+new FargateTaskDefinition(this, 'TaskDefinition', { 
+    runtimePlatform: { cpuArchitecture: CpuArchitecture.ARM64 } 
+}).addContainer('main', {
+    image: armImage.toEcsDockerImageCode(),
+});
+```
+
+The third argument (props) are the super set of DockerImageAsset's properties. You can additionally set `tag` and `repository`.
+
 ### Build SOCI index for a container image
 [Seekable OCI (SOCI)](https://aws.amazon.com/about-aws/whats-new/2022/09/introducing-seekable-oci-lazy-loading-container-images/) is a way to help start tasks faster for Amazon ECS tasks on Fargate 1.4.0. You can build and push a SOCI index using the `SociIndexBuild` construct.
 

src/container-image-build.ts

@@ -13,10 +13,6 @@ import { Construct } from 'constructs';
 import { SingletonProject } from './singleton-project';
 import { ContainerImageBuildResourceProps } from './types';
 
-/**
- * Note:
- *   the default platform is LINUX_AMD64
- */
 export interface ContainerImageBuildProps extends DockerImageAssetProps {
   /**
    * The tag when to push the image
@@ -37,13 +33,8 @@ export interface ContainerImageBuildProps extends DockerImageAssetProps {
   readonly zstdCompression?: boolean;
 }
 
-// reference:
-// https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_ecr_assets.DockerImageAsset.html
-// https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_lambda.AssetImageCodeProps.html
-// https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_ecs.AssetImageProps.html
-
 /**
- * Build Node.js app and optionally publish the artifact to an S3 bucket.
+ * Build a container image and push it to an ECR repository on deploy-time.
  */
 export class ContainerImageBuild extends Construct implements IGrantable {
   public readonly grantPrincipal: IPrincipal;
@@ -189,13 +180,19 @@ curl -v -i -X PUT -H 'Content-Type:' -d "@payload.json" "$responseURL"
     this.imageTag = custom.getAttString('ImageTag');
   }
 
+  /**
+   * Get the instance of {@link DockerImageCode} for a Lambda function image.
+   */
   public toLambdaDockerImageCode() {
     if (this.props.zstdCompression) {
       throw new Error('You cannot enable zstdCompression for a Lambda image.');
     }
     return DockerImageCode.fromEcr(this.repository, { tagOrDigest: this.imageTag });
   }
 
+  /**
+   * Get the instance of {@link ContainerImage} for an ECS task definition.
+   */
   public toEcsDockerImageCode() {
     return ContainerImage.fromEcrRepository(this.repository, this.imageTag);
   }