Creating a Lambda function in AWS - Practice Exercises

Challenge - 5 Problems

❓ service_behavior

intermediate

What happens when a Lambda function is invoked with an event?

Consider an AWS Lambda function configured with a handler that processes incoming events. What is the expected behavior when the function is invoked with a valid event?

A The Lambda function deletes the event without processing it.

B The Lambda function stores the event in S3 and does not execute any code.

C The Lambda function automatically scales to multiple instances without running the handler.

D The Lambda function executes the handler code with the event data and returns a response or error.

💡 Hint

Think about what a Lambda function is designed to do when triggered.

When a Lambda function is invoked, it runs the handler code with the event data and returns a result or error. It does not store or delete events automatically.

❓ Configuration

intermediate

Which IAM role policy allows a Lambda function to write logs to CloudWatch?

You want your Lambda function to write logs to CloudWatch Logs. Which IAM policy statement should be attached to the Lambda execution role?

A {"Effect": "Deny", "Action": ["logs:CreateLogGroup"], "Resource": "*"}

B {"Effect": "Allow", "Action": ["logs:CreateLogGroup", "logs:CreateLogStream", "logs:PutLogEvents"], "Resource": "arn:aws:logs:*:*:*"}

C {"Effect": "Allow", "Action": ["ec2:StartInstances"], "Resource": "*"}

D {"Effect": "Allow", "Action": ["s3:PutObject"], "Resource": "arn:aws:s3:::my-bucket/*"}

💡 Hint

Focus on permissions related to CloudWatch Logs actions.

To allow Lambda to write logs, the role needs permissions to create log groups, streams, and put log events in CloudWatch Logs.

❓ Architecture

advanced

How to design a Lambda function for high availability and fault tolerance?

You need to design a Lambda function that remains highly available and fault tolerant in case of failures. Which architecture approach best achieves this?

A Disable CloudWatch Logs to improve performance and reduce failure points.

B Deploy the Lambda function only in one Availability Zone to reduce latency.

C Deploy the Lambda function in multiple AWS Regions and use Route 53 latency-based routing to invoke the nearest function.

D Use a single Lambda function with no retries configured to avoid duplicate processing.

💡 Hint

Consider geographic redundancy and routing to improve availability.

Deploying Lambda functions in multiple regions with latency-based routing ensures availability even if one region fails.

❓ security

advanced

What is the best practice to secure environment variables in Lambda functions?

You want to store sensitive data like API keys in Lambda environment variables securely. What is the best practice to protect these secrets?

A Encrypt environment variables using AWS KMS and enable Lambda to decrypt them at runtime.

B Store secrets directly in plain text environment variables without encryption.

C Hardcode secrets inside the Lambda function code for faster access.

D Send secrets as part of the event payload when invoking the Lambda function.

💡 Hint

Think about encryption and secure key management.

Encrypting environment variables with AWS KMS and allowing Lambda to decrypt them at runtime protects secrets from exposure.

✅ Best Practice

expert

How to optimize cold start performance for a Lambda function written in Java?

Java Lambda functions often have longer cold start times. Which approach best reduces cold start latency?

A Use provisioned concurrency to keep Lambda instances initialized and ready to serve requests.

B Increase the memory allocation to the minimum value to reduce startup time.

C Avoid using any dependencies and write all code inline in the handler method.

D Disable VPC access to reduce network initialization delays.

💡 Hint

Consider AWS features that keep functions warm.

Provisioned concurrency keeps Lambda instances initialized, reducing cold start latency especially for Java functions.