Environment variables in Lambda in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

How does Lambda handle environment variables during execution?

Consider an AWS Lambda function configured with environment variables. What happens if you update an environment variable value in the Lambda console while the function is running?

A The running function continues using the old environment variable value until it finishes; new invocations use the updated value.

B The running function immediately uses the new environment variable value without restart.

C The running function throws an error due to environment variable change.

D The Lambda service restarts all running instances immediately to apply the new environment variable.

💡 Hint

Think about how environment variables are loaded when a Lambda function starts.

Lambda loads environment variables when a function instance starts. Changing environment variables affects only new instances or new invocations after restart. Running instances keep using the old values.

❓ security

intermediate

Which environment variable setting improves Lambda security?

You want to store sensitive data like API keys in Lambda environment variables. Which option best improves security?

A Use environment variables only for non-sensitive data and hardcode secrets in code.

B Encrypt environment variables using AWS KMS and enable encryption in Lambda settings.

C Store secrets in environment variables without encryption but restrict IAM roles.

D Store secrets directly as plain text environment variables.

💡 Hint

Think about how AWS helps protect sensitive data in Lambda.

Encrypting environment variables with AWS KMS ensures secrets are protected at rest and decrypted only during function execution, improving security.

❓ Configuration

advanced

What is the correct way to reference an environment variable in a Node.js Lambda function?

Given an environment variable named API_ENDPOINT, which code snippet correctly accesses its value inside a Node.js Lambda handler?

AWS

exports.handler = async (event) => {
  // Access environment variable here
};

A const endpoint = process.env.API_ENDPOINT.value;

B const endpoint = process.env['API_ENDPOINT'];

C const endpoint = process.env.get('API_ENDPOINT');

D const endpoint = process.env.API_ENDPOINT;

💡 Hint

Recall how environment variables are accessed in Node.js.

In Node.js, environment variables are accessed via process.env.VARIABLE_NAME. Both dot notation and bracket notation work, but dot notation is simpler and common.

❓ Architecture

advanced

How to manage environment variables across multiple Lambda functions in different environments?

You have multiple Lambda functions deployed in development, staging, and production. What is the best practice to manage environment variables for these environments?

A Hardcode environment variables in each Lambda function code for each environment.

B Use the same environment variables for all environments to avoid confusion.

C Use separate Lambda environment variable configurations per environment and manage them via infrastructure as code tools.

D Store environment variables in a shared S3 file and read it at runtime from each Lambda.

💡 Hint

Think about how to keep environment variables consistent and manageable across environments.

Using infrastructure as code (like CloudFormation or Terraform) to define environment variables per environment ensures consistency, version control, and easy updates.

🧠 Conceptual

expert

What happens if a Lambda environment variable exceeds the size limit?

AWS Lambda has a size limit for all environment variables combined. What is the result if you try to deploy a Lambda function with environment variables exceeding this limit?

A The deployment fails with an error indicating environment variables size exceeded.

B The Lambda function deploys successfully but truncates environment variables at the limit.

C The Lambda function runs but environment variables are ignored at runtime.

D AWS automatically compresses environment variables to fit the limit.

💡 Hint

Consider AWS Lambda deployment constraints and error handling.

AWS Lambda enforces a hard limit on total environment variable size. Deployments exceeding this limit fail with an error, preventing deployment.