AWS Lambda Interview Questions and Answers for 7 years experience

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AWS Lambda Interview Questions (7 Years Experience)

  1. What is AWS Lambda, and how does it differ from EC2?

    • Answer: AWS Lambda is a serverless compute service that lets you run code without provisioning or managing servers. You upload your code, and Lambda executes it in response to events, such as changes in an S3 bucket or an HTTP request via API Gateway. In contrast, EC2 involves managing virtual servers, operating systems, and patching – a significantly more hands-on approach. Lambda is event-driven and scales automatically, while EC2 requires manual scaling and resource management.

  2. Explain the different Lambda execution environments.

    • Answer: Lambda functions run within isolated execution environments. These environments are updated regularly by AWS, providing security patches and runtime updates. You select the runtime environment (e.g., Node.js, Python, Java) when creating the function, and Lambda manages the underlying infrastructure. The execution environment provides necessary libraries and dependencies, ensuring consistency across invocations.

  3. Describe the Lambda lifecycle.

    • Answer: The Lambda lifecycle begins when an event triggers the function. Lambda allocates resources, initializes the runtime environment, and executes the handler function. After execution, Lambda cleans up resources and returns the result. If the function encounters an error or times out, Lambda logs the error and reports the failure. The lifecycle includes phases like initialization, invocation, execution, and cleanup, each managed by AWS.

  4. How do you handle errors in Lambda functions?

    • Answer: Error handling involves using try-catch blocks in your code to catch exceptions. You can log detailed error information using CloudWatch Logs. You can implement retry mechanisms using dead-letter queues (DLQs) to reprocess failed invocations. For synchronous invocations, appropriate HTTP status codes are returned. Asynchronous invocations rely on monitoring and retry mechanisms.

  5. What are Lambda layers, and why are they useful?

    • Answer: Lambda layers are packages of code and data that can be added to your Lambda functions. They're useful for sharing common code, dependencies, or configurations across multiple functions. This promotes code reusability, reduces function size, and simplifies deployment. Layers are versioned and can be updated independently, avoiding redundant code in individual functions.

  6. Explain the concept of Lambda concurrency.

    • Answer: Lambda concurrency refers to the number of Lambda functions that can execute concurrently. AWS limits concurrency per region and per function. You can configure concurrency limits using resource policies or through the AWS Management Console. Reaching the concurrency limit can lead to throttling, where requests are delayed or rejected. Managing concurrency is crucial for scaling applications effectively.

  7. How do you monitor Lambda function performance?

    • Answer: Lambda performance is monitored using CloudWatch metrics and logs. CloudWatch provides metrics on invocation duration, errors, throttles, and concurrency. Logs provide detailed information about function execution, including errors and stack traces. Using CloudWatch dashboards and alarms allows you to proactively identify and address performance issues.

  8. What are Lambda environment variables, and how are they used?

    • Answer: Lambda environment variables are key-value pairs that can be configured for your Lambda functions. They provide a secure way to configure settings like database credentials, API keys, and other sensitive information without hardcoding them into your code. This enhances security and simplifies configuration management across different environments.

  9. Discuss different ways to trigger a Lambda function.

    • Answer: Lambda functions can be triggered by various events, including S3 object uploads, DynamoDB updates, API Gateway requests, SNS messages, Kinesis data streams, scheduled events (CloudWatch Events), and others. The choice of trigger depends on the application's architecture and requirements. Each trigger type involves configuring an event source to invoke the appropriate Lambda function.

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