Sharath Thungathurthi

AWS Lambda

Sharath Kumar Thungathurthi's photo
Sharath Kumar Thungathurthi
·

5 min read

Here are some commonly asked questions and answers related to AWS Lambda:

1. What is AWS Lambda?

Answer:
AWS Lambda is a serverless computing service that lets you run your code without managing any servers. You only pay for the time your code runs. Lambda automatically scales and manages the infrastructure needed to run your code in response to events, such as file uploads, HTTP requests, or data changes.

2. What is a Lambda function?

Answer:
A Lambda function is a small piece of code written in one of the supported languages (e.g., Python, Node.js, Java, etc.) that AWS Lambda runs in response to events. You upload your code to Lambda, and it automatically executes when triggered.

3. What languages are supported by AWS Lambda?

Answer:
AWS Lambda supports a wide variety of programming languages, including:

  • Python

  • Node.js

  • Java

  • Ruby

  • Go

  • .NET (C#)

  • Custom runtimes (using AWS Lambda's custom runtime API)

4. How does AWS Lambda work?

Answer:
AWS Lambda works by:

  1. Uploading your code: You write your function and upload it to AWS Lambda.

  2. Triggering your code: Lambda functions are triggered by events (such as changes in S3 buckets, HTTP requests via API Gateway, or database changes in DynamoDB).

  3. Lambda runs the code: Lambda automatically provisions the infrastructure, runs the function, and scales as needed based on demand.

  4. Automatic scaling: Lambda scales automatically depending on the number of incoming events, meaning it can handle hundreds or thousands of requests in parallel.

5. What is the billing model of AWS Lambda?

Answer:
AWS Lambda charges you based on:

  • Number of requests: You pay for every request your function handles.

  • Execution time: You pay for the compute time consumed by your function in milliseconds (from the time the function starts until it finishes execution).

6. What are AWS Lambda triggers?

Answer:
Lambda triggers are events or services that invoke (trigger) a Lambda function to run. Some common Lambda triggers include:

  • Amazon S3: Trigger Lambda when a new file is uploaded.

  • Amazon DynamoDB: Trigger Lambda when a record in a DynamoDB table is modified.

  • Amazon SNS: Trigger Lambda based on messages sent through an SNS topic.

  • API Gateway: Trigger Lambda when an HTTP request is made to an API endpoint.

  • CloudWatch Events: Trigger Lambda for scheduled tasks or event-driven workflows.

7. Can Lambda functions have access to other AWS services?

Answer:
Yes, Lambda functions can access and interact with many AWS services. For example:

  • Amazon S3: Read from or write to S3 buckets.

  • Amazon DynamoDB: Interact with DynamoDB for database operations.

  • Amazon SNS/SQS: Publish messages or consume messages from queues.

  • AWS KMS: Use KMS for encryption and decryption of sensitive data.

  • Amazon RDS: Connect to relational databases such as MySQL or PostgreSQL.

You can grant Lambda the necessary permissions using IAM roles to allow access to these services.

8. What are the advantages of using AWS Lambda?

Answer:

  • No server management: Lambda automatically handles the infrastructure for you.

  • Cost-efficient: You only pay for the time your code runs. There are no charges when the function is not running.

  • Automatic scaling: Lambda scales automatically to handle any number of requests or events.

  • Easy to integrate: Lambda integrates easily with many AWS services like S3, DynamoDB, SNS, and API Gateway.

  • High availability: Lambda functions are run across multiple availability zones, ensuring high availability.

9. What are the limitations of AWS Lambda?

Answer:

  • Execution time limit: The maximum execution time for a Lambda function is 15 minutes. If your task takes longer, you would need to break it up or use a different service.

  • Memory and CPU limits: Lambda functions can be allocated up to 10 GB of memory, and the available CPU power scales with the amount of memory allocated.

  • Package size limit: The maximum deployment package size for Lambda is 50 MB (for direct upload) or 250 MB (when using Amazon S3).

  • Stateless: Lambda functions are stateless, meaning they do not retain information between executions unless you store data externally (e.g., in S3 or DynamoDB).

10. How do you monitor AWS Lambda functions?

Answer:
You can monitor AWS Lambda functions using:

  • Amazon CloudWatch Logs: Lambda automatically sends logs to CloudWatch, where you can view logs related to function execution (e.g., output, errors).

  • CloudWatch Metrics: Lambda provides key metrics, such as invocation count, duration, errors, and throttles in CloudWatch.

  • CloudWatch Alarms: Set up alarms on Lambda metrics to alert you when certain thresholds are exceeded (e.g., too many errors or timeouts).

  • X-Ray: AWS X-Ray helps with tracing and analyzing Lambda function performance and troubleshooting issues.

11. How do you handle errors in AWS Lambda?

Answer:
You can handle errors in AWS Lambda in the following ways:

  • Error handling within the code: You can add error-handling logic (e.g., try-catch blocks) in your function code.

  • Dead-letter queues (DLQs): If your Lambda function fails after retry attempts, you can configure it to send the event to an SQS queue (DLQ) for further inspection and debugging.

  • Retries: Lambda automatically retries failed invocations for asynchronous functions. You can also configure a maximum retry limit.

  • Notifications: You can use SNS to send notifications about failures or errors.

12. How can Lambda integrate with AWS KMS for encryption?

Answer:
AWS Lambda can use AWS KMS (Key Management Service) for encrypting and decrypting sensitive data. You can:

  • Use KMS keys in your Lambda function to encrypt data before storing it (e.g., in S3) or decrypt data when it's read.

  • Configure IAM roles to grant Lambda the necessary permissions to use KMS keys.

  • Lambda can also use KMS to protect sensitive environment variables that your function might use (e.g., API keys or database credentials).

13. How can Lambda function access environment variables?

Answer:
Lambda functions can access environment variables that you configure when setting up the function. These variables can be used to store configuration data like database connection strings, API keys, or other secrets. Lambda can access these variables securely at runtime.

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