API Gateway

An API Gateway is a critical component in a Microservices architecture, as it serves as a single entry point for external clients to access the Microservices system. It provides a layer of abstraction between the client and the underlying Microservices, and acts as a reverse proxy to route incoming requests to the appropriate Microservice(s). The API Gateway can also handle other cross-cutting concerns such as authentication, rate limiting, load balancing, and caching, which simplifies the development and management of the Microservices system.

Here's an example of how to build an API Gateway using Kong, an open-source API Gateway and Service Mesh platform that's widely used in production environments.

• Install Kong on your local machine or a server. You can follow the installation instructions on the Kong website.
• Start Kong using the command-line interface:

• Use the Kong Admin API to define a new API that will serve as the entry point for the Microservices system:

This creates a new API named "my-api" that routes requests to the Microservice at http://my-microservice:8080. Requests to the http://localhost:8000/api endpoint will be forwarded to the Microservice, as this is the uris property value.

• Add a new plugin to the API that enables rate limiting:

This adds the rate-limiting plugin to the "my-api" API, with a limit of 10 requests per minute.

• Start your Microservice, and make sure it's accessible at the upstream URL defined in the API.
• Test the API Gateway by sending a request to the http://localhost:8000/api endpoint. The request should be forwarded to the Microservice, and the response should be returned to the client through the API Gateway.

That's it! With just a few commands, we've built a basic API Gateway using Kong that routes requests to a Microservice and provides rate-limiting functionality.

Here's an example of how to build an API Gateway using Tyk, another popular open-source API Gateway platform:

• Install Tyk on your local machine or a server. You can follow the installation instructions on the Tyk website.
• Start the Tyk Gateway using the command-line interface:

This creates a new organization and user account for the Tyk Gateway.

• Configure a new API definition in the Tyk Dashboard:

• Log in to the Tyk Dashboard by visiting http://localhost:3000 in your web browser.
• Click the "APIs" tab in the left-hand menu.
• Click the "Add New API" button.
• Fill out the form with the necessary details for your API, including the upstream URL for your Microservice.
• Save the API definition.

• Add a new rate-limiting policy to the API definition:

• Click the "Policies" tab in the left-hand menu.
• Click the "Add Policy" button.
• Fill out the form with the necessary details for your rate-limiting policy, such as the maximum number of requests per minute.
• Save the policy.

• Apply the rate-limiting policy to the API definition:

• Click the "APIs" tab in the left-hand menu.
• Click the name of the API you created in step 3.
• Click the "Policies" tab.
• Click the "Add Policy" button.
• Select the rate-limiting policy you created in step 4.
• Save the changes.

• Start your Microservice and make sure it's accessible at the upstream URL defined in the API.
• Test the API Gateway by sending a request to the API endpoint defined in the API definition. The request should be forwarded to the Microservice, and the response should be returned to the client through the Tyk Gateway.

That's it! With just a few steps, we've built a basic API Gateway using Tyk that routes requests to a Microservice and provides rate-limiting functionality.

Note that these examples are just a starting point, and a real-world API Gateway would likely include additional functionality such as authentication, load balancing, and other features to make it more scalable, resilient, and fault-tolerant. However, Kong and Tyk provide a powerful and flexible foundation for building API Gateways in a Microservices architecture.