When you use Google Cloud Platform, a GCE L7 load balancer often serves your Kubernetes Ingress. By default, the health check path is set to a standard value. Many users want to change this path to match their application needs. In this article, we will explain why this is important and how you can set a custom health check path. We use simple language and short sentences so beginners can follow along.
Introduction
Kubernetes Ingress is used to expose your services to the internet. In Google Cloud, when you create an Ingress resource, it automatically creates a GCE L7 load balancer. This load balancer comes with a built-in health check. The health check verifies if your application is running and ready to serve traffic.
By default, the health check path is usually set to “/”. But many applications have a different endpoint for health checks. For example, your application might return status information at “/healthz” or “/status”. In such cases, you need a custom health check path.
This article shows you how to update the health check path in your Ingress configuration. We also cover basic ideas about Ingress, load balancers, and networking in Kubernetes. For more on setting up Ingress, you can read about configuring ingress for external access to my applications.
How GCE L7 Load Balancer Works with Kubernetes Ingress
When you create an Ingress in Kubernetes, the controller creates a Google Cloud load balancer. This load balancer is a Layer 7 (L7) proxy. It looks at the HTTP request and makes routing decisions based on rules that you define in the Ingress resource.
The load balancer also performs health checks on the backend services. These health checks help determine if a backend is healthy. If a backend fails the check, the load balancer will not send traffic to it.
By default, the health check is set to a fixed path. This default may not be the best for all applications. Changing the health check path can ensure that the load balancer uses the proper URL to check your application’s health.
Understanding how Kubernetes handles networking can be very useful. You can learn more about Kubernetes networking basics by reading how does kubernetes networking work.
The Importance of Health Checks
Health checks are important because they make sure that only healthy backends receive traffic. The load balancer periodically sends requests to the health check path. If the application returns a success status code, it is marked healthy. If not, the load balancer stops sending traffic to that backend.
Many applications use a custom endpoint to report their health. This endpoint can do more than just return a 200 OK. It may check database connections, cache status, or other critical services. In such cases, using a custom health check path is necessary to get an accurate view of your service’s health.
Also, using a custom path can help avoid false negatives. For example, if your application’s root path “/” serves redirects or public pages, the default health check might get confused. A custom health check endpoint provides a clear and dedicated route for health signals.
How to Customize the Health Check Path
Google Cloud Ingress does not directly let you set a custom health check path through the Ingress resource. Instead, you must use annotations to pass this configuration to the GCE load balancer.
There is an annotation you can use called ingress.gcp.kubernetes.io/healthcheck-path. You add this annotation to your Ingress resource. This tells the controller to use your specified path when configuring the health check.
Below is a sample Ingress YAML that sets a custom health check path:
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: my-ingress
annotations:
ingress.gcp.kubernetes.io/healthcheck-path: "/custom-health"
spec:
rules:
- host: myapp.example.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: my-service
port:
number: 80
In this example, the annotation ingress.gcp.kubernetes.io/healthcheck-path is set to /custom-health. This means that the health check will call this URL on your service. Make sure that your service returns a healthy status when this endpoint is hit.
Deploying on Google Cloud
If you run your Kubernetes cluster on Google Cloud using GKE, the process is similar. The Ingress controller in GKE creates the GCE L7 load balancer. When you set the annotation in your Ingress, the GCE load balancer will update its health check settings accordingly.
Before you apply your changes, it is a good idea to verify that your GKE cluster is set up correctly. For more details on setting up your cluster in Google Cloud, check out how do I deploy a kubernetes cluster on google cloud GKE.
After deploying, use the kubectl describe ingress my-ingress command to verify that your annotation is applied. You can also check the health check configuration in the Google Cloud Console.
Understanding Kubernetes Services and Load Balancing
A Kubernetes Service defines how to access a set of pods. In a cloud environment, Services often integrate with load balancers. The GCE L7 load balancer is one example. It forwards traffic from the internet to the correct Service, which then routes to your pods.
It is important to know how services expose your application. This understanding helps you design better and more secure applications. For a deeper dive into the topic, you can explore what are kubernetes services and how do they expose applications.
Another important point is that Google Cloud’s load balancer uses health checks to decide which backend pods are available. By setting a custom health check path, you make sure that only pods that are truly healthy receive traffic.
The Role of Different Types of Services
There are different types of services in Kubernetes, and they work in various ways with external load balancers. For instance, ClusterIP services are used for internal traffic while LoadBalancer services expose your application externally.
In the case of GCE L7 load balancers, the Ingress controller works with a Service of type LoadBalancer. It is useful to understand the differences between service types. You can read more about the various options in what are the different types of kubernetes services.
Each service type has its benefits. LoadBalancer services are easy to set up in cloud environments and work well with Ingress. They provide a single external IP and support features like health checks.
Using Kubectl to Verify Your Configuration
Once you apply your Ingress with the custom health check annotation, you need to check that the settings are correct. The kubectl command line tool is very useful for this. You can use it to describe resources and verify annotations.
For example, run:
kubectl describe ingress my-ingress
This command shows you the details of your Ingress resource. Look for the annotation and confirm that it shows your custom path /custom-health. If you do not see it, check your YAML file and try again.
It is important to learn how to use kubectl to manage and troubleshoot your cluster. For more basic commands and tips, you can review what is kubectl and how do I use it to manage kubernetes.
Troubleshooting Common Issues
Sometimes the custom health check path may not work as expected. Here are some common problems and solutions:
Annotation Not Applied
If your annotation is missing, the load balancer will use the default path. Check your Ingress YAML for proper indentation and syntax.Backend Service Misconfiguration
Make sure that your backend Service and pods are set up correctly. The health check URL must be accessible from the load balancer. Verify your Service configuration.Application Endpoint Issues
Confirm that your application listens on the custom health check path. You can test this by curling the endpoint from inside the cluster.Delayed Updates
Sometimes changes to the Ingress take time to propagate. Give the system a few minutes and check again in the Google Cloud Console.
Troubleshooting is an important skill when managing Kubernetes clusters. Use logs and monitoring tools to help identify issues.
Best Practices for Custom Health Checks
Here are some tips to ensure a smooth experience with custom health check paths:
Keep Your Health Endpoint Simple
The endpoint should return a clear success status. Avoid complex logic that may delay the response.Document Your Configuration
Clearly comment your YAML files to explain why you use a custom health check path. This helps team members understand your setup.Monitor Your Health Checks
Use Google Cloud Console to monitor health check status. Regular monitoring helps catch issues early.Test Changes in a Staging Environment
Before applying changes in production, test them in a staging cluster. This prevents downtime and unexpected behavior.
By following these best practices, you can improve the reliability of your application and ensure that only healthy pods receive traffic.
Conclusion
Custom health check paths are an important tool for fine-tuning your application's availability. When using a GCE L7 load balancer with Kubernetes Ingress, you may need to set a health check path that differs from the default. This article explained the role of health checks and showed you how to set a custom path using annotations.
We learned that the Ingress controller uses annotations to pass configuration details to the GCE load balancer. By adding the annotation ingress.gcp.kubernetes.io/healthcheck-path to your Ingress, you can specify a custom health check URL. We also discussed how the load balancer works with your Services and pods.
Understanding Kubernetes networking and services is key to successful configuration. It is also important to verify your changes using kubectl and the Google Cloud Console. For more insights into Kubernetes services and exposing applications, you might explore the guide on what are kubernetes services and how do they expose applications.
In addition, learning about the different types of Kubernetes services can help you choose the right one for your needs. A detailed look at this topic is available in what are the different types of kubernetes services.
Deploying your cluster on Google Cloud requires careful planning and setup. For guidance on creating a robust environment, check out how do I deploy a kubernetes cluster on google cloud GKE.
Finally, knowing how to use kubectl is essential for managing your cluster. For a beginner-friendly introduction, refer to what is kubectl and how do I use it to manage kubernetes.
By applying these techniques and best practices, you can set up a custom health check path for your GCE L7 load balancer. This helps ensure that your application is accurately monitored and that only healthy pods serve traffic. With clear configuration and regular monitoring, you can maintain a reliable and scalable environment in your Kubernetes cluster.
Happy coding and good luck with your Kubernetes projects!
Top comments (0)