Tutorial / Cram Notes
Amazon API Gateway
Amazon API Gateway is a managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale.
Configuration Steps:
- API Creation: Start by creating a new API in the API Gateway console. Choose between REST, HTTP, or WebSocket API depending on your needs.
- Resource and Methods: Create resources (like paths or URIs) and define methods (GET, POST, DELETE, etc.) on those resources.
- Integration Type: Choose an integration type for each method. This could be a Lambda function, an HTTP endpoint, or a mock endpoint for testing.
- Deploy API: Once configured, deploy your API to a stage. Stages represent different versions or environments for your API (like dev, test, prod).
- Throttling: Set up throttling rules to protect your backend services from traffic spikes.
- Usage Plans: Optionally, create usage plans to manage and restrict client request rates.
- Monitoring and Logging: Enable CloudWatch logs and set up monitoring to keep an eye on API performance and errors.
AWS Lambda
AWS Lambda lets you run code without provisioning or managing servers. You pay only for the compute time you consume.
Configuration Steps:
- Function Creation: In the AWS Lambda console, begin by creating a new Lambda function. You can author from scratch, use a blueprint, or deploy an application from the AWS Serverless Application Repository.
- Runtime and Code: Select a runtime for your function (supported languages include Node.js, Python, Ruby, Java, Go, .NET, etc.), and then upload your code either directly in the editor or via a ZIP file from Amazon S3.
- Handler Configuration: Specify the function handler, which is the entry point for your Lambda function (e.g.,
index.handlerfor a Node.js function). - Permissions: Define the execution role that grants your function permission to use AWS services and resources.
- Memory and Timeout: Allocate memory to your function and set the maximum execution time (timeout).
- Triggers: Set up triggers such as Amazon S3 events, Amazon DynamoDB streams, API Gateway endpoints, or direct invocations.
- Environment: Configure environment variables to manage configuration data and secrets separately from your code.
AWS Fargate
AWS Fargate is a serverless compute engine for containers. With Fargate, you no longer have to provision, configure, or scale clusters of virtual machines to run containers.
Configuration Steps:
- Task Definitions: Start by creating a task definition, which is a blueprint for your application that specifies the containers you want to run.
- Container Definitions: Within the task definition, add container definitions for each container image, specify the CPU and memory requirements, environment variables, log configuration, and command or entry point.
- Service Creation: Create a service in the Amazon ECS console that defines how your task definitions are run. Specify things like the desired number of tasks, the network configuration, and the load balancer (if any).
- Cluster: While Fargate removes the need for manually managing servers, tasks still run in an Amazon ECS cluster. However, with Fargate, this is a logical grouping rather than a physical cluster of servers.
- Networking: Configure the VPC, subnets, and security groups to control the network access to and from your Fargate tasks.
- Scaling: Optionally, set up Application Auto Scaling to adjust the desired count of tasks automatically based on custom metrics.
- CI/CD Integration: Integrate with CI/CD pipelines for automated deployments using AWS CodePipeline and CodeBuild.
Conclusion
For serverless applications on AWS, optimizing configurations comes down to balancing scalability, performance, security, and cost. Each service—Amazon API Gateway, AWS Lambda, and AWS Fargate—has its specific configurations, but they often integrate together to form a modern serverless application.
Leveraging these services requires an in-depth understanding of AWS best practices, which is essential for clearing the AWS Certified DevOps Engineer – Professional exam. While this overview provides the basic configuration steps, exam candidates should dive into the AWS documentation and whitepapers, as well as gain hands-on experience to build a robust foundation in configuring serverless AWS applications.
Practice Test with Explanation
True or False: Amazon API Gateway cannot trigger AWS Lambda functions directly.
- (A) True
- (B) False
Answer: B) False
Explanation: Amazon API Gateway can indeed trigger AWS Lambda functions directly without the need for additional infrastructure.
When deploying a serverless application, which AWS service can be used to create a deployment package?
- (A) AWS CodeCommit
- (B) AWS CodeBuild
- (C) AWS CodeDeploy
- (D) AWS Lambda
Answer: B) AWS CodeBuild
Explanation: AWS CodeBuild is used to compile source code and create deployment packages for serverless applications, which can include AWS Lambda functions.
True or False: AWS Lambda functions can only be triggered by AWS services.
- (A) True
- (B) False
Answer: B) False
Explanation: AWS Lambda functions can be triggered by AWS services and can also be invoked directly through the AWS SDKs or the AWS CLI.
Multiple Select: Which of the following are valid event sources for triggering an AWS Lambda function?
- (A) S3 events
- (B) API Gateway requests
- (C) Direct AWS CLI invocations
- (D) Manual invocations via AWS Management Console
Answer: A) S3 events, B) API Gateway requests, C) Direct AWS CLI invocations, D) Manual invocations via AWS Management Console
Explanation: All these options are valid event sources that can trigger an AWS Lambda function.
Which service is best suited for running containers without having to manage servers or clusters?
- (A) Amazon Elastic Container Service (ECS)
- (B) AWS Fargate
- (C) Amazon Elastic Kubernetes Service (EKS)
- (D) AWS Lambda
Answer: B) AWS Fargate
Explanation: AWS Fargate allows you to run containers without managing servers or clusters and is a serverless compute engine for containers.
True or False: AWS Lambda supports blue/green deployment strategy out-of-the-box.
- (A) True
- (B) False
Answer: B) False
Explanation: AWS Lambda does not support blue/green deployments natively, but you can implement such deployment strategies using AWS CodeDeploy in conjunction with Lambda.
Multiple Select: Which of the following are true regarding Amazon API Gateway?
- (A) It can transform and route HTTP requests to different downstream services.
- (B) It automatically scales with the number of incoming requests.
- (C) It can only be used with AWS Lambda as a backend service.
- (D) It supports versioning and stage variables.
Answer: A) It can transform and route HTTP requests to different downstream services, B) It automatically scales with the number of incoming requests, D) It supports versioning and stage variables.
Explanation: Amazon API Gateway can interface with a variety of backend services, not just AWS Lambda, and it does support request transformation, routing, auto-scaling, as well as versioning and stage variables.
True or False: AWS Fargate runs your containers only if they are defined as part of an Amazon ECS task definition.
- (A) True
- (B) False
Answer: A) True
Explanation: AWS Fargate requires you to define your containers as part of an Amazon ECS task definition to manage and run the containers.
Which AWS service would you use to connect an AWS Lambda function to a VPC?
- (A) AWS Direct Connect
- (B) Amazon Route 53
- (C) AWS NAT Gateway
- (D) AWS Lambda VPC Connector
Answer: D) AWS Lambda VPC Connector
Explanation: AWS Lambda functions can be connected to a VPC using the AWS Lambda VPC Connector, which allows Lambda functions access to resources within a VPC.
True or False: When using Amazon API Gateway, traffic encryption between the client to the gateway can be optionally turned off.
- (A) True
- (B) False
Answer: B) False
Explanation: Encryption in transit between the client and Amazon API Gateway is mandatory, and traffic is encrypted using HTTPS/SSL.
Which of the following AWS services is used to orchestrate serverless workflow in coordination with AWS Lambda functions?
- (A) AWS Step Functions
- (B) AWS Elastic Beanstalk
- (C) AWS CodePipeline
- (D) Amazon Simple Workflow Service (SWF)
Answer: A) AWS Step Functions
Explanation: AWS Step Functions is a serverless function orchestrator that makes it easy to sequence AWS Lambda functions into serverless workflows.
True or False: AWS Lambda supports container images as a deployment package format.
- (A) True
- (B) False
Answer: A) True
Explanation: AWS Lambda supports the deployment of Lambda function code as container images, allowing the use of custom runtimes and dependencies.
Interview Questions
Interview Question 1: Can you explain what serverless means in the context of AWS services, and what are the benefits of using a serverless architecture?
Serverless architecture refers to a setup where the developer does not have to manage the servers on which the back-end services run. In the context of AWS, it includes services such as AWS Lambda for compute, Amazon API Gateway for APIs, and AWS Fargate for running containers without managing servers or clusters. The benefits include no server management, automatic scaling, high availability, and a pay-for-use billing model which reduces cost.
Interview Question 2: How would you configure an Amazon API Gateway to handle a sudden surge in traffic?
You would enable throttling in the API Gateway settings to define limits on the number of requests per second and the burst capacity. You may also use Amazon CloudWatch to monitor and set alarms for traffic and utilize AWS Auto Scaling to automatically adjust capacity to maintain steady performance.
Interview Question 3: What are some of the common triggers you can use for AWS Lambda functions, and how would you configure one?
Common triggers for AWS Lambda include Amazon S3 events, Amazon DynamoDB update streams, Amazon Kinesis streams, Amazon SNS notifications, and API Gateway requests. To configure a trigger, you select the AWS service you want to be the source of the trigger and specify the event or resource change that would invoke the Lambda function.
Interview Question 4: Explain how you can manage configuration changes to Lambda functions in a CI/CD pipeline.
Lambda function configurations can be managed using infrastructure as code tools, such as AWS CloudFormation or Terraform. These allow you to define the Lambda function configuration in code, enabling automated deployment and versioning through a CI/CD pipeline.
Interview Question 5: How do you ensure that a set of serverless applications is secure?
To ensure security, you need to implement identity and access management (IAM) policies to secure access to AWS services, use VPCs if necessary to isolate resources, encrypt sensitive data using AWS KMS, and follow the principle of least privilege when assigning roles and permissions to Lambda functions and other resources.
Interview Question 6: What are the differences between Amazon ECS, AWS Lambda, and AWS Fargate, and what criteria would you use to determine when to use each?
Amazon ECS is a container management service used to run Docker containers. AWS Lambda is a compute service that lets you run code without provisioning or managing servers. AWS Fargate is a serverless compute engine for containers that works with both Amazon ECS and Amazon EKS. The criteria for using each depends on the need for server management, containerization, granular scaling, and how frequently the task or service will run.
Interview Question 7: How would you set up an API in the Amazon API Gateway to connect to a Lambda function?
To set up an API in Amazon API Gateway to connect to Lambda, you would first create a new API in the API Gateway console, define the resource and method, and then integrate the method with a Lambda function by selecting the Lambda Function as an integration type and specifying the name of the function.
Interview Question 8: Can you describe the differences between cold and warm starts in AWS Lambda, and how to mitigate issues related to cold starts?
A cold start happens when a Lambda function is invoked after not having been used for an extended period, leading to slower start-up times as AWS provisions new resources. A warm start occurs when the function is already initialized. To mitigate cold starts, you can use provisioned concurrency, which keeps a specified number of instances ready at all times, or utilize AWS Lambda layers to reduce the package size.
Interview Question 9: How do you monitor and debug AWS Lambda functions?
AWS Lambda functions can be monitored using Amazon CloudWatch, which provides metrics, logs, and can create alarms for monitoring function activity. To debug Lambda, you can use CloudWatch Logs to access function logs, set up X-Ray tracing for more detailed insights, or perform local debugging by mocking the AWS environment.
Interview Question 10: Discuss how AWS Fargate contributes to the serverless ecosystem and what are its typical use cases.
AWS Fargate is a serverless compute engine for containers, removing the need to manage servers or clusters, contributing to the serverless ecosystem by simplifying container management. Typical use cases for Fargate include microservices architectures, batch processing jobs, and any application that can be containerized and could benefit from automatic scaling and managed infrastructure.
This blog post was extremely helpful in configuring API Gateway with Lambda. Thanks a lot!
How do you handle versioning in AWS Lambda?
Does anyone know the best practices for setting up Fargate with ECS?
Thanks! This tutorial greatly simplified my understanding of serverless architecture.
I found this post very confusing.
Can someone explain how to use IAM roles with Lambda functions?
This helped me clear a lot of doubts I had about AWS Fargate.
What are the costs associated with using API Gateway?