Running multiple LoadBalancer services in your cluster can be useful but is often unintentionally wasteful. Each LoadBalancer service you create will provision a new load balancer and external IP address from your cloud provider, increasing your costs.

Ingress is a better way to publicly expose multiple services using HTTP routes. Installing an Ingress controller such as Ingress-NGINX lets you direct traffic between your services based on characteristics of incoming HTTP requests, such as URL and hostname.

With Ingress, you can use a single load balancer to serve all your applications. Only add another load balancer when your application requires an additional external IP address, or manual control over routing behavior.

Why Using Multiple Load Balancers Can Be Wasteful

Increased Costs

Every time you create a LoadBalancer service in Kubernetes, your cloud provider provisions a new load balancer along with an external IP address. This can quickly become costly, especially if you’re running multiple services that don’t necessarily need their own dedicated load balancer. The more LoadBalancer services you create, the higher your cloud infrastructure costs will be.

Resource Inefficiency

Beyond cost, running multiple load balancers can also be resource-inefficient. Each load balancer consumes additional network and compute resources, which could otherwise be allocated to your workloads. This inefficiency can lead to unnecessary overhead and underutilized resources within your cluster.

Why Ingress Controllers Are a Better Solution

Consolidating Traffic Management

Ingress controllers allow you to manage traffic for multiple services through a single entry point. By defining Ingress resources, you can route HTTP and HTTPS traffic to different services based on characteristics such as URL paths or hostnames. This consolidation means you only need one load balancer to serve all your applications, significantly reducing both cost and complexity.

Flexible Routing

With Ingress, you gain more control over how traffic is routed to your services. For example, you can direct traffic to different services based on subdomains, paths, or even request headers. This level of flexibility is not available when using individual LoadBalancer services for each application.

Example Ingress Resource

Here’s an example of how you might define an Ingress resource to route traffic to multiple services:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
    - host: example.com
      http:
        paths:
          - path: /app1
            pathType: Prefix
            backend:
              service:
                name: app1-service
                port:
                  number: 80
          - path: /app2
            pathType: Prefix
            backend:
              service:
                name: app2-service
                port:
                  number: 80

In this example, traffic to example.com/app1 is routed to app1-service, while traffic to example.com/app2 is routed to app2-service. All of this is handled by a single load balancer.

When to Use Multiple Load Balancers

While consolidating services under a single load balancer is often the most efficient approach, there are scenarios where using multiple load balancers makes sense:

  • Need for Multiple External IP Addresses: If your applications require different external IP addresses for security or compliance reasons, you may need to provision multiple load balancers.

  • Specific Routing Requirements: In some cases, you might need manual control over routing behavior that goes beyond what an Ingress controller can provide. This could include advanced traffic management features that are specific to your cloud provider’s load balancer service.

  • Scaling Concerns: If a single load balancer cannot handle the traffic for all your services, you might need to distribute the load across multiple load balancers to ensure availability and performance.

Best Practices for Load Balancer Usage

To optimize the use of load balancers in your Kubernetes cluster, consider the following best practices:

  • Use Ingress Controllers: Whenever possible, use an Ingress controller to manage traffic for multiple services. This approach reduces the number of load balancers required and consolidates traffic management.

  • Monitor Load Balancer Costs: Keep an eye on your cloud provider’s billing to monitor the costs associated with running multiple load balancers. Identify opportunities to consolidate services under fewer load balancers.

  • Evaluate Performance Regularly: Regularly evaluate the performance of your load balancers and Ingress controllers to ensure they are meeting your application’s needs. Adjust your setup as necessary to maintain optimal performance and cost-efficiency.

  • Plan for Scalability: If you anticipate scaling your applications significantly, plan your load balancer strategy accordingly. Ensure that your approach can handle increased traffic without becoming a bottleneck.

Conclusion

Using multiple load balancers in Kubernetes can quickly become expensive and inefficient. By leveraging Ingress controllers, you can consolidate traffic management under a single load balancer, reducing costs and simplifying your infrastructure. However, there are situations where multiple load balancers may still be necessary, depending on your application’s specific requirements.

Take the time to evaluate your use of load balancers and consider adopting Ingress to optimize your Kubernetes deployments. This approach will help you maintain a cost-effective, efficient, and scalable environment for your applications.