How to add S3 BucketPolicy with AWS CDK

Question

I wanna translate this CloudFormation piece into CDK:

Type: AWS::S3::BucketPolicy
Properties:
  Bucket:
    Ref: S3BucketImageUploadBuffer
  PolicyDocument:
    Version: "2012-10-17"
    Statement:
      Action:
        - s3:PutObject
        - s3:PutObjectAcl
      Effect: Allow
      Resource:
        - ...

Answer 1

In AWS CDK, there are two ways to build a bucket policy:

utilise the addToResourcePolicy function on a Bucket class object.
Create an instance of the BucketPolicy class.
With the addToResourcePolicy method, we take an implicit approach: once we add a policy statement to the bucket, CDK constructs a bucket policy for us.

The second technique is explicit and a little easier to understand for the reader of our code.

This article's code may be found on GitHub.
Let's take a look at a real-life example of both. First, let's look at the addToResourcePolicy method:

lib/cdk-starter-s