Top 17 Interview Questions and Answers on AWS Lambda

AWS Lambda - Top Interview Questions

AWS Lambda, a serverless computing service has become a top choice for software developers in building cloud applications. As a software developer, you must focus on writing the code rather than thinking about how to manage your servers. One of the best things about this service is that you will need to pay for the computing time you use. We have curated its features into different answers to make the interview easy for you.

 

Key Features of AWS Lambda

AWS Lambda Interview Questions and Answers

1. Top 5 AWS Lambda interview questions for freshers

  1. What is Application Auto Scaling?
  2. Describe automated deployment in your own words.
  3. Is it possible to execute multiple AWS Lambda functions simultaneously?
  4. What makes AWS Lambda different from EC2?
  5. What are some drawbacks of AWS Lambda?

 

2. Top 6 AWS Lambda interview questions for intermediate

  1. Which features of AWS Lambda have been used for automation?
  2. How can you simplify the development process using Lambda layers?
  3. Provide five events to trigger AWS Lambda?
  4. What are the three benefits of implementing AWS Lambda or similar serverless platforms?
  5. What are the available storage options for AWS Lambda?
  6. Can Elastic Blockage Storage (EBS) work with AWS Lambda?

 

3. Top 6 AWS Lambda interview questions for experienced

  1. Share the three best security practices on AWS Lambda.
  2. Share three reasons that make AWS Lambda unique among other serverless platforms.
  3. What are some potential use cases of AWS Lambda.
  4. Explain troubleshooting AWS Lambda or other similar serverless platforms
  5. What is AMI, and how to create it?
  6. Explain automation in serverless applications like AWS Lambda

 

Key Features of AWS Lambda

Some of the key features of AWS Lambda are such as:

  • It supports multiple programming languages - Java, C#, Python, Go, Ruby code, Node.js, and PowerShell.
  • Permits the benefit of the custom logic to use AWS resources like DynomaDb tables and S3 buckets.
  • Allows the creation of customized coding and backend services like mobile backend services.
  • Offers automatic scaling, automated deployment, and integrated security models.
  • Flexible, high-available, fault-tolerant, and an effective integrator.

 

AWS Lambda Interview Questions and Answers

We have compiled a set of AWS Lambda questions and answers for every level to help you here.

 

1. Top 5 AWS Lambda interview questions for freshers

 

1. What is Application Auto Scaling?

AWS Lambda automatically scales out for incoming requests if all existing execution contexts (lambda instances) are busy. It will also automatically scale down the instances during less load on the servers. You can utilize this feature for creating function instances during high demands of computing resources such as memory, CPU, or others without impacting the service performance.

 

2. Describe automated deployment in your own words.

Automated deployment is a process of moving code fully or semi-automatically from the initial development stage to the final development stage. Automation saves time, reduces human errors, and increases efficiency. But, sometimes, the same automation causes issues like long feedback loops, high cost, and poor coding.

 

3. Is it possible to execute multiple AWS Lambda functions simultaneously?

Yes. The availability of the default safety threshold allows users to run many functions simultaneously and control their execution. There is no restriction to running any specific Lambda functions.

 

4. What makes AWS Lambda different from EC2?

AWS Lambda is a serverless and event-based AWS service for running codes without managing servers or instances. Whereas Amazon EC2 is a cloud computing service that provides a platform for creating powerful virtual machine instances (VM instances) or servers in the cloud. With Amazon EC2, you can select any VM instance, but AWS Lambda permits you to write code and upload it to the cloud by invoking functions. You can create a trigger in AWS lambda for creating EC2 instances.

AWS Lambda at a glance
Image Credit: TechTarget

 

5. What are some drawbacks of AWS Lambda?

Function-based computing service, AWS Lambda, has the following 3 main drawbacks:

  • Creating a temporary container or a cold-start time to execute functions for a very short duration ( 100 milliseconds to 2 minutes) is a major drawback. It overheads the repetition of execution for the same processes again.
  • Computational restrictions like default deployment package size (50 MB), memory range (128 MB to 10, 240 MB), and limited disk space (only 512 MB)
  • Lack of control over the environment while developing third-party applications because AWS is the main decision-maker in controlling.

 

2. Top 6 AWS Lambda interview questions for intermediate

 

1. Which features of AWS Lambda have been used for automation?

The following features of AWS Lambda support automation

  • Environmental variables: AWS Lambda has various environmental variables to setup any deployment process. These variables have been used as credential data to bring changes during deployment.
  • Aliases: AWS Lambda supports different aliases which could be used during automation pipeline, stage production, and deployment.
  • Functions: These codes perform testing without impacting other production codes. It further keeps end-points intact, making it easy to align any task.

 

2. How can you simplify the development process using Lambda layers?

A Lambda layer refers to an archive containing additional codes like dependencies, data, custom runtimes, libraries, and configuration files. It reduces the size of uploaded archives and deploys the processes quickly. You can use the AWS Lambda layer to package code libraries into a place and share them with Lambda functions. By bundling, you can simplify the development process.

 

3. Provide five events to trigger AWS Lambda?

AWS Lambda or any other serverless platform contains invoked functions through events. You can use any of the following major events to trigger AWS Lambda or its functions:

  • Amazon API Gateway: It is a standard, secured, and scalable gateway for creating web API that routes HTTP requests for the Lambda function.
  • Dynamo DB: The event is used to invoke the Lambda function for processing records in a queue or data stream stored in the Amazon DynamoDB stream. When an event is invoked, the function reads a record from the data stream and processes it.
  • Amazon S3: This event is used for processing Amazon S3 objects by invoking a Lambda function. For example, while creating, deleting, or updating an object, the event could be used for triggering the Lambda function. Users need to configure notification settings on a bucket and grant permission to invoke functions.
  • Amazon SQS: The Simple Queue Service or SQS event triggers the Lambda function for processing messages in Amazon SQS. Like other events, the event enables the function to read messages in batches and delete them from the queue after processing.
  • AWS Step functions: This event is used for connection Lambda functions to state machines or serverless workflow.

 

4. What are the three benefits of implementing AWS Lambda or similar serverless platforms?

Serverless platforms like AWS Lambda offers many benefits, but the three primary benefits are as follow:

  • Reduction in execution cost as you need to pay only for computing costs. AWS takes care of everything, including the number of instances and scaling services. You don't need to pay for idle time, which reduces execution costs.
  • Managed AWS infrastructure reduces the overhead of the underlying managing servers. It saves lots of time on different operation tasks like managing layers and upgrading operating systems.
  • Automating scaling and deployment saves time and costs.

 

5. What are the available storage options for AWS Lambda?

Amazon has provided many storage options for AWS Lambda. The main storages are as follows:

  • Amazon S3: Amazon Simple Storage Service or simply Amazon S3 is the most common storage option. It allows you to store and access unstructured and massive data. You must use it only for static web content and media storage.
  • EBS: Elastic Blockage Storage or EBS is block-level storage used with Amazon EC2 instances. The durability feature of this storage permits you to store data which frequently changes and needs long-term persistence. You must avoid temporary and high-durable data storage.
  • EC2 instance storage: Amazon Elastic Compute Cloud or EC2 instance storage is temporary block storage for EC2 instances. You must avoid storing valuable or critical data because of its temporary storage feature.
  • Amazon EFS: Amazon Elastic File System or simply EFS is another serverless storage option that allows storing data without provisioning. This storage automatically grows and shrinks when you add or remove data. You can easily mount it with AWS Lambda.

All these storages are durable. You can either access it as an individual or integrated way.

 

6. Can Elastic Blockage Storage (EBS) work with AWS Lambda?

Yes, it works. EBS is basically a virtual storage area network where tasks can be started. AWS Lambda supports all of the services offered by AWS. It is fault-tolerant which makes it easy to detect faults quickly. Moreover, it removes the concern of data loss in case of disk failure in RAID. Using provisioning, you can easily connect EBS to APIs. Some key features are as follows:

  • Supports optimized performance
  • Secured and high available storage
  • Offers easy data-back and restoration

 

3. Top 6 AWS Lambda interview questions for experienced

 

1. Share the three best security practices on AWS Lambda.

The shared responsibility model has been followed to enable security within AWS Lambda (see image).

best security practices on AWS Lambda
Image Credit: AWS Amazon
 

AWS is responsible for taking care of infrastructure security standards like Identity Access and Management (IAM) permissions & roles, VPC & networking settings, etc. And you need to take care of applications and other cloud configurations. You can adopt the following three best security practices:

  • Granting least privilege, IAM for Lambda functions is the best security practice. Each Lambda function should be configured with one IAM role to permit accessing essential resources only. You can configure IAM for implementing resource-based policies to check the authorization of services that invoke functions.
  • Avoid storing AWS configuration in Lambda execution configuration or function code. Keeping it in EC2 System Manager Parameter Store or Lambda environment variables is good.
  • Utilize API Gateway to add an additional layer of security to the functions. It uses encryption, authentication, and request throttling to enable security. It makes changes in API configuration and authorization settings.

 

2. Share three reasons that make AWS Lambda unique among other serverless platforms.

AWS Lambda has the potential to perform server provisioning, security, monitoring, code deployment, or running web services. Its features make it the first choice for development and deployment. Let's see three main reasons:

  • The pricing model saves huge costs by paying only for what you use.
  • Multiple languages and open-source frameworks support deploying an application and performing data processing in AWS Lambda.
  • The completely event-driven feature of AWS Lambda runs it while invoking functions. As a software developer, you always prefer to use it for those applications services which have periods and peaks in traffic.

 

3. What are some potential use cases of AWS Lambda.

Processing data at scale, creating event-driven applications, and running web/mobile backends are evergreen applications of AWS Lambda. These applications support you to create real use cases. Let's see three famous use cases:

  • Operating serverless websites: It is getting popular because of its pricing model, S3 storage, and hosting.
  • Predictive page rendering: It prepares web pages for display based on how users will select them on the subsequent requests. For example, You can resize the images for various gadgets after uploading them into S3 storage.
  • Developing a futuristic app: Another use case to save cost, time & effort while managing infrastructure and other deployment processes.

 

4. Explain troubleshooting AWS Lambda or other similar serverless platforms

Many issues can arise when using AWS Lambda or other similar serverless platforms. Different issues related to deployment, invocation, execution, networking, or container image might occur while using Lambda. You need to follow specific functions or services for troubleshooting any issue. The following table suggests the relevant positions regarding AWS Lambda to troubleshoot issues:

Issue type Services/Functions
Deployment AWS CloudFormation, AWS CodeDeploy, AWS CodePipeline
Invocation Use specific functions based on invoking issues
Execution Use AWS CloudWatch Logs and X-Ray
Networking Need to make changes in Virtual Private Cloud (VPC) configuration
Container Image Use specific functions based on issues

 

5. What is AMI, and how to create it?

AMI stands for the Amazon Machine Image that contains the necessary information for launching an instance. Amazon EBS snapshots, launch permissions, and block device mapping are three main elements of AMI. Generally, we call it a template to use with the AWS service.

You must use the same configuration to launch many instances using a single AMI. But use different configurations to launch different instances using different AMIs.

Amazon Machine Image (AMI) Service
Image Credit: Amazon
 

You can use Lambda functions to create AMI. Steps for creating AMI are as follow:

  • Use an existing AMI for launching an instance from a trusted AMI
  • Customized it by adding components like installing software
  • Save this configuration and named it “custom AMI”
  • You can launch instances from this custom AMI

 

6. Explain automation in serverless applications like AWS Lambda

Generally, an integrated continuous delivery pipeline is used for creating and deploying applications automatically. The pipeline connects the resources to each other to enable continuous delivery. Regarding AWS Lambda, AWS CodePipeline is used for the same purpose. You need to configure a pipeline to call the Lambda function to execute tasks such as modeling, visualizing, etc.

Another deployment option is "CodeDeploy." It automates applications deployments to AWS Lambda, Amazon EC2 instances, on-premises instances, or Amazon EC2 services. CodeDeploy is a good option for rolling deployment for Lambda functions. Besides Lambda functions, you can deploy codes, packages, scripts, executables, multimedia files, and web and configuration files.

We hope that we have covered all essential concepts to answer AWS Lambda interview questions that are mostly asked by the interviewer. In case you have queries, do let us know in the comment box. Also, it is suggested to get familiar with AWS services would be beneficial for you for creating applications on the serverless platform.

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