API Gateway Throttling and Usage Plans for Serverless APIs
In serverless architectures, AWS API Gateway acts as the front door for your applications, managing incoming API requests and routing them to your backend services like AWS Lambda. To ensure stability, prevent abuse, and manage costs, API Gateway provides powerful mechanisms for controlling API access: Throttling and Usage Plans.
Understanding API Gateway Throttling
Throttling is a critical feature that limits the number of requests your API can accept within a given time period. This protects your backend services from being overwhelmed by traffic spikes, ensuring consistent performance and availability. API Gateway allows you to configure throttling at two levels: the API level and the method level.
Throttling prevents API overload by setting request limits.
Throttling defines the maximum number of requests an API or specific method can handle per second (rate) and the maximum number of requests that can be burst at any given time (burst capacity).
API Gateway throttling is configured using two primary parameters: the request rate and the burst limit. The request rate is the average number of requests per second that API Gateway will allow. The burst limit is the maximum number of requests that can be processed in a short period, allowing for temporary spikes in traffic without immediately hitting the rate limit. When these limits are exceeded, API Gateway returns a 429 Too Many Requests error to the client.
API-Level vs. Method-Level Throttling
| Feature | API-Level Throttling | Method-Level Throttling |
|---|---|---|
| Scope | Applies to all methods within an API. | Applies to a specific API method (e.g., GET /users). |
| Granularity | Broader control, useful for overall API protection. | Finer control, allows different limits for different operations. |
| Use Case | Setting a general cap on total API traffic. | Protecting a resource-intensive GET operation or a sensitive POST operation. |
You can configure both API-level and method-level throttling. If both are set, the most restrictive limit applies. This provides flexibility in managing your API's performance.
Introducing Usage Plans
Usage Plans go a step further than basic throttling by allowing you to define specific throttling and quota limits for different groups of users or applications. This is achieved by associating API stages with a Usage Plan and then granting access to specific APIs via API keys.
Usage Plans enable tiered access control and customized rate limiting.
Usage Plans allow you to create different tiers of access for your API, each with its own throttling limits and quotas, managed through API keys.
A Usage Plan consists of:
- Throttling Limits: The rate and burst limits applied to requests made using API keys associated with this plan.
- Quota Limits: The maximum number of requests allowed within a specific time period (e.g., 10,000 requests per month).
- API Keys: Unique identifiers that clients must include in their requests to be recognized by the Usage Plan.
- Associated APIs/Stages: The specific APIs and their stages that the Usage Plan applies to.
Think of API keys as digital passports for your API users. Usage Plans then dictate how many times each passport holder can enter (make requests) and how quickly they can move (throttling).
How Usage Plans Work with API Keys
When a client makes a request to an API stage associated with a Usage Plan, they must include an API key in the
x-api-key
Throttling limits and quota limits.
Benefits of Throttling and Usage Plans
Implementing throttling and usage plans offers several key benefits for your serverless APIs:
- Cost Management: Prevents unexpected costs by controlling the volume of requests processed by Lambda and other backend services.
- Service Stability: Protects your backend from overload, ensuring consistent performance and availability for all users.
- Security: Mitigates the risk of denial-of-service (DoS) attacks by limiting the rate of incoming requests.
- Tiered Service Offerings: Enables you to create different service levels for various customer segments, monetizing your API effectively.
Practical Considerations
When configuring throttling and usage plans, consider the expected traffic patterns of your API and the capacity of your backend services. Start with conservative limits and gradually adjust them based on monitoring and performance data. Remember to communicate these limits to your API consumers.
429 Too Many Requests
Learning Resources
Official AWS documentation detailing how to configure throttling for your API Gateway APIs, including rate and burst limits.
Comprehensive guide from AWS on setting up usage plans, API keys, and associating them with API stages for access control and rate limiting.
A practical blog post from AWS explaining the concepts of throttling and how to implement them effectively for serverless applications.
This AWS Builders' Library article covers best practices for building serverless APIs, including sections on API Gateway features like throttling.
A YouTube video that visually explains the concepts of API Gateway throttling and usage plans, demonstrating their configuration.
While a book, this study guide often contains detailed explanations and examples relevant to API Gateway features like throttling and usage plans for certification preparation.
A Medium article that delves into the nuances of API Gateway throttling, offering practical tips and common pitfalls to avoid.
Another helpful YouTube tutorial demonstrating the setup and functionality of quotas and throttling within AWS API Gateway.
AWS's official best practices for API Gateway, which includes recommendations on security, performance, and cost optimization, often touching upon throttling.
AWS's overview of serverless architectures, providing context on how API Gateway fits into the broader ecosystem and its role in managing APIs.