Do microservices require API Gateways?
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Modern commerce and microservices
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An API gateway is a software app found between a client and a set of backend microservices.
The API Gateway works as a reverse proxy, accepts API calls from the client application and forwards this traffic to the relevant service. The API gateway also performs other functions such as enforcing security and ensuring high availability and scalability.
Why should Microservices have an API Gateway
In this article, we attempt to show you why API Gateways are critical parts of microservices architecture. We will also discuss the common features of an API gateway, the challenges that an API gateway has to overcome and some pointers that you have to keep in mind when you choose to use an API Gateway.
API Gateways – Why they are required
A microservice architecture presents many advantages to users as well as challenges that have to be addressed. API gateways are built to address such challenges.
1. Centralized access to Decentralized Microservices
A microservice architecture application typically works as modules/functions and each service focuses on implementing a specific business action. This design pattern enables easy development testing, deployment, and maintenance of different capabilities of an application. Nevertheless, this design means increased complexity for the clients to access these services.
Nevertheless, an API gateway is designed to handle several calls simultaneously and route them to the services appropriately. It also can split a single call into multiple requests to different services and consolidate the results as they respond.
2. Management and discovery for scalable, distributed services
An elastic cloud allows horizontal scaling of services whenever demand surges are encountered. However, for this, efficient load balancing, resiliency features like retries and timeouts, and easier ways to discover services are to be incorporated.
API gateways offer better utilization of resources by managing load balancing between replicas of the same service. Whereas traditional proxies employ load balancing algorithms like ‘Random or Round Robin’, API Gateways are designed to use sophisticated algorithms such as weighted connections/least connections, or custom implementations that help to leverage the service registry. These techniques are used to provide efficient traffic routing. The API can do this as it simultaneously implements features such as retries whenever a service is down, rerouting requests to healthy service instances, or error handling.
3. Microservice Language and protocol independence abstraction
In microservices, the different services are built independently using different technologies and protocols. As an example, developers could develop a service in Java, implement it as a RESTful API, or write it in Go and implement it using a gRPC protocol interface. Of course, this language and protocol independence allows for a lot of flexibility. It also means that clients have to understand and implement different communication protocols to access these APIs.
The advantage of the API Gateway lies in the fact that it can translate between the different protocols, thus allowing clients to call any service they require using a single protocol. API Gateways work to effectively hide service implementations from the client applications. With the interface definition remaining the same, developers can bring about desired changes to the service logic using any preferred technology stack without the client even knowing it.
This means a service previously written in Java can be rewritten in Python and redeployed behind the API gateway. The interface will remain the same and the client action is not affected. It calls the same function using the same parameters and produces the same results without identifying the underlying technology and although the logic may have changed.
4. Routing to Microservices based on deployment strategies
During deployment, any improvements to the features and bug fixes have to be handled specially. Teams can adopt different strategies for this such as canary release or blue/green deployments. However, they have to ensure that they have already optimized their CI/CD pipelines to fit these strategies.
API gateways can be configured in a manner so that they route traffic according to the chosen strategies, thereby switching/routing traffic between the old and new service versions appropriately.
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5. Traffic control to prevent overloading of resources
Front-end services that face the Internet can be subject to malicious attacks and exploitation of different kinds. They have to be made capable to handle sudden demand surges from valid users and, of course, the troublemakers. So request throttling and blacklist capabilities are required to be built in to keep systems secure and reliable.
API gateways form effective barriers against Distributed Denial of Service (DDoS) attacks by throttling the number of requests made to the affected services. This prevents the services from being overwhelmed and also protects them from becoming unresponsive.
API Gateways – Common Features and Benefits
An API gateway forms the outer edge of your microservices system and acts as a proxy to manage all incoming traffic. For this to happen, the API Gateway has to be endowed with several features.
- Authentication - Authorization- Audit
Any request made to service has to be authenticated to ensure access only for valid users. An API gateway is designed to authenticate all traffic before routing it to the service that has been called. The API gateway can either perform the authentication by itself or can be designed to use external authentication providers.
The authorization ensures that your users have the necessary access permissions to request a specific action from a service. Just like with authentication, an API gateway can use its access control lists (ACL) for authorization or fetch the information from external service providers.
Since all calls have to pass through the API Gateway, system administrators have, in their hands, an invaluable audit trail of who accessed the service when, and for what purpose. This makes it easy for troubleshooting errors, monitor performance, or address security incidents.
- Managing Traffic
Traffic management is core to any API Gateway. The API gateway is a virtual endpoint for the API clients, and this number remains the same over time. This reduces the requirement for any disruptive change for the clients when services or versions are deployed. This ultimately makes way for a better developer experience.
When using Kubernetes, a container orchestration platform meant for the cloud, it is easy to scale up services across multiple nodes inside a cluster or across many clusters. This also means that ephemeral services having locations (IP address and port) are constantly changing. An API gateway can help with a service registry to keep track of the available instances of each service.
As and when services integrate with the API gateway, they self-register with the service registry and make known their presence and availability. Third-party registration services may also be used. A service registry helps the gateway to route the client request at any time to the appropriate service.
- Threat Protection
An API gateway can protect services from spikes/DDoS attacks. DevOps teams can program to smooth or throttle traffic by implementing failure patterns such as circuit breaking or protecting services from becoming overloaded with requests.
An API Gateway can prevent attacks by inspecting incoming requests. By integrating with other Security Information and Event Management (SIEM) systems or fraud detection systems, it can decide whether the request is a genuine or a fraudulent one. Some of its other tasks are:
API Firewalling helps to mitigate application-level threats such as Cross-Site Request Forgery (CSRF) and SQL injection (some API gateways can integrate with WAFs), and also detects and blocks threats with help from blacklisting bots or the OWASP Top Ten.
Content Validation by the API gateway ensures that each request has correctly formatted input parameter values for the specific service and that they adhere to the API’s published interface.
Integrity Validation helps to confirm that requests have not been tampered with and encrypted data in the request/response body is kept confidential.
- Monitoring and Observability
If required, an API gateway can collect logs, metrics, and traces of all inbound traffic that passes through it. Based on this data, it can be made to track request and response times, error trends, and traffic patterns.
The API gateway can log important messages in both directions to help troubleshoot errors and also improve the observability of the system. The API gateway’s location in the system allows it to add tracing information such as correlation ID, and this enables visibility of requests which come through the system.
Along with a unified observability solution, integrated API gateways can help you to keep a check on a distributed application’s overall performance. The gateway’s proactive alerting rules can be made to report on the different services’ health before they become unresponsive.
Using API Gateways – Caveats to be kept in Mind
When your organization decide to use API gateways that bring many benefits, there are some caveats to be borne in mind.
An API Gateway is a software component that the DevOps/APIOps team has to deploy, configure, and maintain. This equates to an extra part of the architecture that incurs additional cost in terms of money, time, and effort and has a learning curve.
The extra component placed between clients and the microservices means there would be an extra network hop for client requests. Depending on the network speed, this may have an adverse effect on the response time of the service.
An API gateway, being the entry point for all the services, could become a single point of failure and cause your entire system to go down. Therefore, API gateways have to be configured so that they are highly available. It can also be a single point of attack for malicious players. A compromised gateway may cause your microservices to become vulnerable to outsider attacks.
Any architectural decision will have its pros and cons. It is the same with an API gateway. A well-designed and properly configured API Gateway can strengthen your microservice-based application with capabilities such as load balancing, traffic management, threat protection, and observability. Ensure that you understand the problems your system and application have to address before installing an API gateway.
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How SayOne can Assist in Microservices Development
At SayOne, our integrated teams of developers service our clients with microservices that are fully aligned to the future of the business or organization. The microservices we design and implement are formulated around the propositions of Agile and DevOps methodologies. Our system model focuses on individual components that are resilient, fortified, and highly reliable.
We design microservices for our clients in a manner that assures future success in terms of scalability and adaptation to the latest technologies. They are also constructed to accept fresh components easily and smoothly, allowing for effective function upgrades in a cost-effective manner.
Our microservices are constructed with reusable components that offer increased flexibility and offer superior productivity for the organization/business. We work with start-ups, SMBs, and enterprises and help them to visualise the entire microservices journey and also allow for the effective coexistence of legacy systems of the organization.
Our microservices are developed for agility, efficient performance and maintenance, enhanced performance, scalability, and security.
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