S3SubscriptionSample

LambdaSharp S3 Bucket Events Source

Before you begin, make sure to setup your LambdaSharp CLI.

Module Definition

Creating a function that is invoked by a S3 bucket events requires two steps. First, either create or reference an S3 bucket in the Items section. Second, the function must reference the bucket in its Sources section using the S3 attribute.

Optionally, the S3 attribute can specify specific S3 events to listen to, an S3 key prefix and suffix.

Module: Sample.S3.Subscription
Description: A sample module integrating with S3 Bucket events
Items:

  - Resource: MyFirstBucket
    Description: The S3 Bucket the function is listening to
    Type: AWS::S3::Bucket
    Allow: ReadWrite

  - Resource: MySecondBucket
    Description: The S3 Bucket the function is listening to
    Type: AWS::S3::Bucket
    Allow: ReadWrite

  - Function: MyFunction
    Description: This function is invoked by an S3 Bucket event
    Memory: 128
    Timeout: 30
    Sources:

      # listen to `s3:ObjectCreated:*` on the bucket
      - S3: MyFirstBucket

      # listen to custom events on specific S3 keys
      - S3: MySecondBucket
        Events:
          - "s3:ObjectCreated:*"
          - "s3:ObjectRemoved:*"
        Prefix: images/
        Suffix: .png

Function Code

The S3 event can be parsed into a S3Event message instance by using the ALambdaFunction<TRequest,TResponse> base class and including the Amazon.Lambda.S3Events nuget package.

public sealed class Function : ALambdaFunction<S3Event, string> {

    //--- Methods ---
    public override Task InitializeAsync(LambdaConfig config)
        => Task.CompletedTask;

    public override async Task<object> ProcessMessageAsync(S3Event s3Event) {
        LogInfo($"# S3 Records = {s3Event.Records.Count}");
        for(var i = 0; i < s3Event.Records.Count; ++i) {
            var record = s3Event.Records[i];
            LogInfo($"EventName = {record.EventName.Value}");
            LogInfo($"EventSource = {record.EventSource}");
            LogInfo($"EventTime = {record.EventTime}");
            LogInfo($"EventVersion = {record.EventVersion}");
            LogInfo($"S3.Bucket.Name = {record.S3.Bucket.Name}");
            LogInfo($"S3.Object.ETag = {record.S3.Object.ETag}");
            LogInfo($"S3.Object.Key = {record.S3.Object.Key}");
            LogInfo($"S3.Object.Size = {record.S3.Object.Size}");
            LogInfo($"S3.Object.VersionId = {record.S3.Object.VersionId}");
            LogInfo($"UserIdentity.PrincipalId = {record.UserIdentity.PrincipalId}");
        }
        return "Ok";
    }
}