Tutorial: Using AWS Lambda with Amazon DocumentDB Streams

Consuming a Amazon DocumentDB event with Lambda using .NET.

using Amazon.Lambda.Core;
using System.Text.Json;
using System;
using System.Collections.Generic;
using System.Text.Json.Serialization;
//Assembly attribute to enable the Lambda function's JSON input to be converted into a .NET class.
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))]

namespace LambdaDocDb;

public class Function
{
    
     /// <summary>
    /// Lambda function entry point to process Amazon DocumentDB events.
    /// </summary>
    /// <param name="event">The Amazon DocumentDB event.</param>
    /// <param name="context">The Lambda context object.</param>
    /// <returns>A string to indicate successful processing.</returns>
    public string FunctionHandler(Event evnt, ILambdaContext context)
    {
        
        foreach (var record in evnt.Events)
        {
            ProcessDocumentDBEvent(record, context);
        }

        return "OK";
    }

     private void ProcessDocumentDBEvent(DocumentDBEventRecord record, ILambdaContext context)
    {
        
        var eventData = record.Event;
        var operationType = eventData.OperationType;
        var databaseName = eventData.Ns.Db;
        var collectionName = eventData.Ns.Coll;
        var fullDocument = JsonSerializer.Serialize(eventData.FullDocument, new JsonSerializerOptions { WriteIndented = true });

        context.Logger.LogLine($"Operation type: {operationType}");
        context.Logger.LogLine($"Database: {databaseName}");
        context.Logger.LogLine($"Collection: {collectionName}");
        context.Logger.LogLine($"Full document:\n{fullDocument}");
    }



    public class Event
    {
        [JsonPropertyName("eventSourceArn")]
        public string EventSourceArn { get; set; }

        [JsonPropertyName("events")]
        public List<DocumentDBEventRecord> Events { get; set; }

        [JsonPropertyName("eventSource")]
        public string EventSource { get; set; }
    }

    public class DocumentDBEventRecord
    {
        [JsonPropertyName("event")]
        public EventData Event { get; set; }
    }

    public class EventData
    {
        [JsonPropertyName("_id")]
        public IdData Id { get; set; }

        [JsonPropertyName("clusterTime")]
        public ClusterTime ClusterTime { get; set; }

        [JsonPropertyName("documentKey")]
        public DocumentKey DocumentKey { get; set; }

        [JsonPropertyName("fullDocument")]
        public Dictionary<string, object> FullDocument { get; set; }

        [JsonPropertyName("ns")]
        public Namespace Ns { get; set; }

        [JsonPropertyName("operationType")]
        public string OperationType { get; set; }
    }

    public class IdData
    {
        [JsonPropertyName("_data")]
        public string Data { get; set; }
    }

    public class ClusterTime
    {
        [JsonPropertyName("$timestamp")]
        public Timestamp Timestamp { get; set; }
    }

    public class Timestamp
    {
        [JsonPropertyName("t")]
        public long T { get; set; }

        [JsonPropertyName("i")]
        public int I { get; set; }
    }

    public class DocumentKey
    {
        [JsonPropertyName("_id")]
        public Id Id { get; set; }
    }

    public class Id
    {
        [JsonPropertyName("$oid")]
        public string Oid { get; set; }
    }

    public class Namespace
    {
        [JsonPropertyName("db")]
        public string Db { get; set; }

        [JsonPropertyName("coll")]
        public string Coll { get; set; }
    }
}

Consuming a Amazon DocumentDB event with Lambda using Go.

package main

import (
	"context"
	"encoding/json"
	"fmt"

	"github.com/aws/aws-lambda-go/lambda"
)

type Event struct {
	Events []Record `json:"events"`
}

type Record struct {
	Event struct {
		OperationType string `json:"operationType"`
		NS            struct {
			DB   string `json:"db"`
			Coll string `json:"coll"`
		} `json:"ns"`
		FullDocument interface{} `json:"fullDocument"`
	} `json:"event"`
}

func main() {
	lambda.Start(handler)
}

func handler(ctx context.Context, event Event) (string, error) {
	fmt.Println("Loading function")
	for _, record := range event.Events {
		logDocumentDBEvent(record)
	}

	return "OK", nil
}

func logDocumentDBEvent(record Record) {
	fmt.Printf("Operation type: %s\n", record.Event.OperationType)
	fmt.Printf("db: %s\n", record.Event.NS.DB)
	fmt.Printf("collection: %s\n", record.Event.NS.Coll)
	docBytes, _ := json.MarshalIndent(record.Event.FullDocument, "", "  ")
	fmt.Printf("Full document: %s\n", string(docBytes))
}

Consuming a Amazon DocumentDB event with Lambda using JavaScript.

console.log('Loading function');
exports.handler = async (event, context) => {
    event.events.forEach(record => {
        logDocumentDBEvent(record);
    });
    return 'OK';
};

const logDocumentDBEvent = (record) => {
    console.log('Operation type: ' + record.event.operationType);
    console.log('db: ' + record.event.ns.db);
    console.log('collection: ' + record.event.ns.coll);
    console.log('Full document:', JSON.stringify(record.event.fullDocument, null, 2));
};

Consuming a Amazon DocumentDB event with Lambda using TypeScript

import { DocumentDBEventRecord, DocumentDBEventSubscriptionContext } from 'aws-lambda';

console.log('Loading function');

export const handler = async (
  event: DocumentDBEventSubscriptionContext,
  context: any
): Promise<string> => {
  event.events.forEach((record: DocumentDBEventRecord) => {
    logDocumentDBEvent(record);
  });
  return 'OK';
};

const logDocumentDBEvent = (record: DocumentDBEventRecord): void => {
  console.log('Operation type: ' + record.event.operationType);
  console.log('db: ' + record.event.ns.db);
  console.log('collection: ' + record.event.ns.coll);
  console.log('Full document:', JSON.stringify(record.event.fullDocument, null, 2));
};

Consuming a Amazon DocumentDB event with Lambda using PHP.

<?php

require __DIR__.'/vendor/autoload.php';

use Bref\Context\Context;
use Bref\Event\Handler;

class DocumentDBEventHandler implements Handler
{
    public function handle($event, Context $context): string
    {

        $events = $event['events'] ?? [];
        foreach ($events as $record) {
            $this->logDocumentDBEvent($record['event']);
        }
        return 'OK';
    }

    private function logDocumentDBEvent($event): void
    {
        // Extract information from the event record

        $operationType = $event['operationType'] ?? 'Unknown';
        $db = $event['ns']['db'] ?? 'Unknown';
        $collection = $event['ns']['coll'] ?? 'Unknown';
        $fullDocument = $event['fullDocument'] ?? [];

        // Log the event details

        echo "Operation type: $operationType\n";
        echo "Database: $db\n";
        echo "Collection: $collection\n";
        echo "Full document: " . json_encode($fullDocument, JSON_PRETTY_PRINT) . "\n";
    }
}
return new DocumentDBEventHandler();

Consuming a Amazon DocumentDB event with Lambda using Python.

import json

def lambda_handler(event, context):
    for record in event.get('events', []):
        log_document_db_event(record)
    return 'OK'

def log_document_db_event(record):
    event_data = record.get('event', {})
    operation_type = event_data.get('operationType', 'Unknown')
    db = event_data.get('ns', {}).get('db', 'Unknown')
    collection = event_data.get('ns', {}).get('coll', 'Unknown')
    full_document = event_data.get('fullDocument', {})

    print(f"Operation type: {operation_type}")
    print(f"db: {db}")
    print(f"collection: {collection}")
    print("Full document:", json.dumps(full_document, indent=2))

Consuming a Amazon DocumentDB event with Lambda using Ruby.

require 'json'

def lambda_handler(event:, context:)
  event['events'].each do |record|
    log_document_db_event(record)
  end
  'OK'
end

def log_document_db_event(record)
  event_data = record['event'] || {}
  operation_type = event_data['operationType'] || 'Unknown'
  db = event_data.dig('ns', 'db') || 'Unknown'
  collection = event_data.dig('ns', 'coll') || 'Unknown'
  full_document = event_data['fullDocument'] || {}

  puts "Operation type: #{operation_type}"
  puts "db: #{db}"
  puts "collection: #{collection}"
  puts "Full document: #{JSON.pretty_generate(full_document)}"
end

Consuming a Amazon DocumentDB event with Lambda using Rust.

use lambda_runtime::{service_fn, tracing, Error, LambdaEvent};
use aws_lambda_events::{
    event::documentdb::{DocumentDbEvent, DocumentDbInnerEvent},
   };


// Built with the following dependencies:
//lambda_runtime = "0.11.1"
//serde_json = "1.0"
//tokio = { version = "1", features = ["macros"] }
//tracing = { version = "0.1", features = ["log"] }
//tracing-subscriber = { version = "0.3", default-features = false, features = ["fmt"] }
//aws_lambda_events = "0.15.0"

async fn function_handler(event: LambdaEvent<DocumentDbEvent>) ->Result<(), Error> {
    
    tracing::info!("Event Source ARN: {:?}", event.payload.event_source_arn);
    tracing::info!("Event Source: {:?}", event.payload.event_source);
  
    let records = &event.payload.events;
   
    if records.is_empty() {
        tracing::info!("No records found. Exiting.");
        return Ok(());
    }

    for record in records{
        log_document_db_event(record);
    }

    tracing::info!("Document db records processed");

    // Prepare the response
    Ok(())

}

fn log_document_db_event(record: &DocumentDbInnerEvent)-> Result<(), Error>{
    tracing::info!("Change Event: {:?}", record.event);
    
    Ok(())

}

#[tokio::main]
async fn main() -> Result<(), Error> {
    tracing_subscriber::fmt()
    .with_max_level(tracing::Level::INFO)
    .with_target(false)
    .without_time()
    .init();

    let func = service_fn(function_handler);
    lambda_runtime::run(func).await?;
    Ok(())
    
}