Common Issues When Configuring AWS Load Balancer Controller on EKS

Amazon Elastic Kubernetes Service (EKS) provides a managed environment for deploying, managing, and scaling containerized applications using Kubernetes. Many developers rely on AWS Load Balancer Controller to simplify the management of load balancers, allowing for improved availability and fault tolerance in their applications. However, configuring the AWS Load Balancer Controller can come with its own set of challenges. In this blog post, we will explore common issues that may arise during the configuration process and how to overcome them.

Understanding the AWS Load Balancer Controller

Before diving into the issues, it is crucial to understand what the AWS Load Balancer Controller does. It implements the Kubernetes Ingress resource and is responsible for provisioning Application Load Balancers (ALBs) and Network Load Balancers (NLBs) in AWS. With a well-configured controller, you can achieve dynamic routing, SSL termination, and fine-grained access control.

Why Use AWS Load Balancer Controller?

1. Automation: Automatically provisions load balancers when you create Ingress resources in your Kubernetes cluster.
2. Enhanced Security: It supports AWS WAF and security groups for better protection.
3. Cost-Effectiveness: AWS Load Balancer Controller allows you to optimize costs by using ALBs instead of NLBs when appropriate.

Common Configuration Issues

1. IAM Permissions

Issue: One of the most frequent issues is related to IAM permissions. The controller requires certain permissions to create load balancers and manage resources.

Solution: Make sure that the IAM role attached to your EKS worker nodes has the necessary permissions to interact with Amazon Resource Names (ARNs). Here's a sample IAM policy you can use:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "elasticloadbalancing:*",
                "ec2:*",
                "iam:ListAttachedRolePolicies",
                "iam:ListRolePolicies",
                "iam:GetRole",
                "iam:GetRolePolicy",
                "iam:ListRoleTags"
            ],
            "Resource": "*"
        }
    ]
}

Why: This policy allows the AWS Load Balancer Controller to create and manage resources required for load balancing.

2. Incorrect Annotations

Issue: Misconfigured annotations on your Ingress resource can lead to load balancer failures.

Solution: Make sure to use the correct annotations corresponding to your load balancer types. For example, to create an ALB, the following annotations are essential:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-ingress
  annotations:
    alb.ingress.kubernetes.io/scheme: internet-facing
    alb.ingress.kubernetes.io/target-type: ip
spec:
  rules:
    ...

Why: These annotations instruct the Load Balancer Controller on the desired configuration of the ALB, such as its accessibility and target type, which is crucial for proper routing.

3. Network Configuration Issues

Issue: This includes issues with VPC, subnets, and security groups. If your cluster is not correctly set up within your VPC, it can lead to connectivity problems.

Solution: Ensure that your Kubernetes nodes are in public or private subnets as appropriate, and that the necessary security groups allow traffic. Also, review your subnet configurations. Here's a basic example to attach a security group:

aws ec2 modify-network-interface-attribute --network-interface-id <eni-id> --groups <sg-id>

Why: Security groups should allow traffic on the necessary ports (e.g., 80 and 443) to enable communication with your applications.

4. SSL Certificates Not Configured

Issue: If you're planning to use HTTPS through your ALB, not having a valid SSL certificate issued can lead to configuration issues.

Solution: Leverage AWS Certificates Manager (ACM) to create and manage your SSL certificates. After creating a certificate, use the following annotation in your Ingress resource:

alb.ingress.kubernetes.io/certificate-arn: arn:aws:acm:<region>:<account-id>:certificate/<certificate-id>

Why: Specifying the ARN for your SSL certificate ensures that the ALB can terminate TLS connections, allowing secure communication.

5. Service Type Mismatches

Issue: The service type associated with your Kubernetes service can affect load balancer functionality. For example, using a ClusterIP service type will not work with the AWS Load Balancer Controller.

Solution: Use NodePort or LoadBalancer type services as shown in the following example:

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  type: LoadBalancer
  ports:
    - port: 80
      targetPort: 8080
  selector:
    app: my-app

Why: By defining a service type as LoadBalancer, you're instructing Kubernetes to provision a LoadBalancer-type service.

6. Health Check Failures

Issue: Your ALB health checks might fail due to misconfiguration in the health check settings or an unresponsive backend service.

Solution: Ensure that the health check path and interval match your application’s readiness probe. Here's an example of a correct configuration in your deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  template:
    spec:
      containers:
        - name: my-container
          image: my-image
          readinessProbe:
            httpGet:
              path: /health
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 10

Why: Proper health check settings ensure that your ALBs route traffic only to services that are truly healthy, improving application reliability.

7. Conflicts with Existing Load Balancers

Issue: Attempting to create a new Ingress resource could lead to conflicts with existing load balancers if they are improperly defined.

Solution: Review existing load balancers within your AWS console. Use the below command to check Ingress configurations:

kubectl get ingress -n <namespace>

Why: Knowing existing resources helps you avoid conflicts and facilitates smoother deployments.

Final Considerations

Configuring the AWS Load Balancer Controller on EKS can be simplified by understanding the common issues that may arise and how to address them. From ensuring proper IAM permissions to managing configurations and addressing health check failures, each step plays a pivotal role in your overall success.

For further context, you can check out the AWS documentation on Load Balancer Controller or the Kubernetes Ingress documentation.

By applying these solutions and best practices, you'll set yourself up for success in deploying robust, scalable applications on AWS EKS with the Load Balancer Controller. Happy deploying!