Understanding AWS Lambda and Its Triggers

AWS Lambda is a serverless compute service, allowing you to run code without provisioning or managing servers. It automatically scales by running code in response to triggers and only charges for compute time consumed.

Triggers are the mechanisms that start the execution of your Lambda function. AWS services like S3, DynamoDB, and API Gateway can directly invoke your function in response to events such as object creation or table updates.

API Gateway acts as an HTTP endpoint triggering Lambda functions. It's perfect for creating serverless microservices. With custom integration, you can transform requests/responses, and implement authentication and authorization mechanisms.

Event source mapping enables automatic invocation of Lambda functions for services like Kinesis, DynamoDB Streams, and SQS. The service polls the resource and invokes your function with a batch of records.

Amazon CloudWatch Events and EventBridge can schedule the execution of Lambda functions using cron or rate expressions. This enables automated, time-driven execution, ideal for regular maintenance tasks or workflows.

A lesser-known feature is the ability to set up cross-account triggers. By configuring the correct permissions, a Lambda function in one AWS account can be invoked by an event occurring in a different account.

Lambda Destinations allow you to define what happens after your Lambda function executes. You can route the result to another Lambda function, SNS, SQS, or EventBridge for further processing or notifications.