API Gateway plays a critical role in any application developed on Amazon Web Services (AWS). As one prepares for the “AWS Certified Developer – Associate (DVA-C02)” exam, a deep understanding of API Gateway and its components such as stages is crucial.

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What are API Gateway Stages?

To understand stages in API Gateway, it is vital to first understand what an API Gateway is. Essentially, an API Gateway is a fully managed service that facilitates developers to create, manage, secure, and monitor APIs. It acts as a front-door to applications, making it possible to access data, business logic, or functionality.

API Gateway stages, on the other hand, are essentially lifecycle phases of an API. They can be considered as a ‘version’ or a ‘snapshot’ of the API which corresponds to a specific deployment. This categorization allows users to manage their deployments efficiently and promotes environment-based workflows like development, testing, QA and production. The stages indicate various application environments where APIs have been or will be deployed.

Utility of API Gateway Stages

In API Gateway, each API stage is associated with a single deployment and may have its specific configurations, allowing room for differentiation between supposedly similar API stages. This proves useful when different configurations are required at different stages of the API lifecycle. Thus, API Gateway stages facilitate configuration and management, allowing developers to control each stage by setting stage variables, enabling caching, managing throttling, and enlisting SDK generation.

A significant benefit of API Gateway stages is that they enable a user to maintain multiple copies of an API, facilitating simultaneous version management. Additionally, they incorporate settings to control access, throttling, logging, caching etc., enhancing the API Gateway management.

An Example of API Gateway Stages

Assume an application that initially runs in the ‘dev’, ‘qa’, and ‘prod’ stages. A developer prepares an update to enhance its functionalities. Using API Gateway stages, the update is initially deployed in the ‘dev’ stage for testing. If bugs are found, they are fixed, and the fixed version is redeployed in ‘dev’.

Once ‘dev’ testing is successful, the update is deployed to ‘qa’ for further quality control. Any issues encountered are addressed in the ‘dev’ stage then deployed in ‘qa’ again. Once it passes ‘qa’, the update is deployed to ‘prod’ making it the new live version of your API.

Common Configuration Options in API Gateway Stages

When creating or editing stages in API Gateway, developers can configure various options. Here are some of the standard configuration settings:

  • Logging: Enable logging to understand and trace back errors, issues or success logs.
  • Throttling: API Gateway enables you to set up rate limiting to handle traffic spikes and prevent misuse.
  • Access Permissions: You can control who has access to your APIs by setting up IAM roles.
  • Caching: API Gateway also allows you to set up caching to improve performance.

It is advised that candidates for the “AWS Certified Developer – Associate (DVA-C02)” exam understand the different possibilities of API Gateway stages and how to configure them as per requirements. In conclusion, API Gateway stages are integral for an efficient API management and understanding them adds significant value to the developer’s AWS knowledge repository.

Practice Test

True or False: API Gateway stages are snapshots of the API Gateway stack at a point in time.

  • True
  • False

Answer: False

Explanation: API Gateway stages are not snapshots of the API stack. They are named references to a deployment of an API, which act as “environments”.

Which of the following actions can be performed on an API Gateway stage? (multiple select)

  • A. Invoking API methods
  • B. Setting up stage variables
  • C. Configuring settings for caching
  • D. Deploying an API

Answer: A, B, C

Explanation: API Gateway stages allow you to invoke API methods, set up stage variables and also configure settings for caching. Deploying an API is done to a stage but not from within a stage.

True or False: There can only be one active stage at any given time.

  • True
  • False

Answer: False

Explanation: There can be multiple active stages at a given time in API Gateway. These stages are like different working environments.

In API Gateway, what is the purpose of stage variables? (single select)

  • A. To store secure data like passwords
  • B. To pass data between stages
  • C. To maintain specific configurations for each stage
  • D. All of the above

Answer: C

Explanation: Stage variables in API Gateway are used to maintain specific configurations for each stage—like environment-specific variables.

Which of the following statements about API Gateway caching is true? (single select)

  • A. It helps to reduce traffic to the backend systems
  • B. It degrades the performance of APIs
  • C. It can only be enabled at the deployment stage

Answer: A

Explanation: By enabling API Gateway caching, you can cache the response from your endpoint for a specified time. This helps to reduce the number of calls made to your endpoint and also reduces latency for your users.

True or False: It’s not possible to track the performance of a specific stage in API Gateway.

  • True
  • False

Answer: False

Explanation: API Gateway stages are integrated with CloudWatch which allows performance tracking for a specific stage using metrics.

True or False: An API Gateway stage cannot be associated with a specific deployment.

  • True
  • False

Answer: False

Explanation: An API Gateway stage always references a specific deployment of an API.

Single Select: What is the main purpose of API Gateway stages?

  • A. To maintain version control of APIs
  • B. To allow for testing of APIs in different environments
  • C. To monitor the performance of APIs
  • D. All of the above

Answer: B

Explanation: The main purpose of API Gateway stages is to allow the testing of APIs in various environments (like dev, test, prod).

True or False: When you create an API Gateway stage, a new CloudFront distribution is created.

  • True
  • False

Answer: True

Explanation: Every time you create a stage in API Gateway, a new CloudFront distribution is created, unless the stage is associated with a regional endpoint.

True or False: Once created, stage variables cannot be updated or deleted.

  • True
  • False

Answer: False

Explanation: Stage variables in API Gateway can be created, updated and deleted as per the requirements of different stages or environments.

Interview Questions

What is an API Gateway stage in AWS?

In AWS, an API Gateway Stage is a phase within an existing API Gateway where it is deployed. It’s contextualized as different environments (like test, beta, production) to which the gateway API is deployed.

Can you explain the primary purpose of stages in API Gateway?

The primary purpose of stages in API Gateway is to create different environments (like dev, beta, prod) for API version control, enabling developers to test, monitor, and roll out new changes with minimal risk.

Are stage variables supported in AWS API Gateway?

Yes, stage variables are supported in AWS API Gateway. They act as environment variables that can be used to modify API behavior in different stages.

What is the maximum number of stages an API Gateway can have?

There are no specific maximum limits defined for the number of stages an API Gateway can have. However, AWS service limits might vary by region.

What is the use of the “Deployment” tab within AWS API Gateway?

The “Deployment” tab is used to create new stages, manage or configure existing stages, or clone an API Gateway from an existing stage.

How can you enable caching in API Gateway?

Caching can be enabled at the stage level in API Gateway. After it’s enabled, you can specify a TTL (time-to-live) period to control how long the cache data is stored.

Can you enable CloudWatch logging for API Gateway Stages?

Yes, CloudWatch logging can be enabled for different API Gateway stages. This helps in monitoring API calls made to the API Gateway deployment stages.

How is throttling managed in the API Gateway stages?

Throttling at the stage level in API Gateway is set by configuring the method request rates and burst capacity. These control the maximum number of requests per second (RPS) and the maximum number of requests at a time.

Can you explain how to manage access control in API Gateway stages?

Access control for API Gateway stages can be managed through AWS Identity and Access Management (IAM), Amazon Cognito user pools, or Lambda authorizers.

What is the use of the canary release deployment in API Gateway stages?

Canary release deployment allows you to roll out API changes in stages, directing a certain percentage of API traffic to new deployments. This helps in catching potential issues before fully deploying the API.

Can you enable cross-origin resource sharing (CORS) at the API Gateway stage level?

Yes, you can enable CORS at the resource level within a stage or for the whole API stage directly from the API Gateway console.

How do you update an existing API stage in API Gateway?

An existing API stage can be updated by redeploying the updated API to the existing stage or by using the PATCH method provided by API Gateway Stage Update API.

What is the purpose of usage plans in API Gateway stages?

Usage plans in API Gateway stages can be associated with API keys to enable rate limiting and quotas on a per-API key basis.

How to delete API Gateway stages?

API Gateway stages can be deleted using the AWS Management Console, AWS CLI or the API Gateway REST API, by the API Gateway Stage Delete operation.

How do you migrate an API deployment from one stage to another in API Gateway?

An API deployment can be migrated from one stage to another by creating a new deployment in the target stage with the same configuration as the existing stage.

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