10 Kubernetes Health Check Best Practices

Health checks are an important part of any system, and Kubernetes is no different. By default, Kubernetes will perform a health check on each pod to ensure that it is running as expected. However, there are a number of best practices that you can follow to ensure that your Kubernetes health checks are as effective as possible.

In this article, we will discuss 10 Kubernetes health check best practices that you can follow to ensure that your system is running smoothly.

1. Use Liveness and Readiness Probes

Liveness probes are used to detect when a container is no longer running, so that it can be restarted. Readiness probes are used to detect when a container is ready to start accepting traffic.

Using both Liveness and Readiness Probes ensures that your containers are always running and able to accept traffic, which improves the availability of your applications.

It’s also important to configure your health checks so that they are not too frequent, or else you may end up with false positives. For example, if you have a Liveness Probe that is configured to check for a container every minute, but the container only takes 30 seconds to start up, you will get a false positive every time the container is restarted.

Configuring your health checks properly is essential for ensuring the availability of your applications.

2. Set Timeouts for Health Checks

If a container takes too long to start up or shut down, it can cause problems for the Kubernetes system. If a container is taking too long to start up, other containers that depend on it will be unable to start. If a container is taking too long to shut down, it may prevent other containers from starting.

To avoid these problems, it’s important to set timeouts for health checks. By default, Kubernetes has a timeout of 10 seconds for liveness checks and 30 seconds for readiness checks. However, you may want to increase or decrease these timeouts depending on your application’s needs.

It’s also important to note that you should never have a timeout that is shorter than the interval at which the check is performed. For example, if you have a liveness check that is performed every 30 seconds, you should not have a timeout that is shorter than 30 seconds.

3. Avoid Using TCP as a Probe Type

When you use TCP as a probe type, Kubernetes will try to establish a connection with the container on the specified port to determine if it’s healthy. The problem is that this can often lead to false negatives—for example, if the container is taking a long time to start up, the health check will fail even though the container is eventually healthy.

Instead, it’s better to use a different probe type, such as HTTP, HTTPS, or Exec. With these probe types, Kubernetes will make a request to the container and only consider it healthy if it returns a successful response. This avoids false negatives and ensures that your health checks are more accurate.

4. Check the Right Endpoint

If you’re checking the health of an application, you want to make sure that you’re checking the health of the application itself and not just the infrastructure it’s running on. For example, if you have a web application, you would want to check the /healthz endpoint rather than just checking if the pod is up.

The /healthz endpoint will give you information about the actual application, such as whether or not it can connect to the database, rather than just telling you that the pod is up. This is important because you want to make sure that the application is actually healthy and not just that the infrastructure it’s running on is healthy.

Checking the right endpoint is especially important when you’re using Kubernetes liveness and readiness probes because these probes are used to determine whether or not an application is healthy and should be restarted or taken out of service. If you’re checking the wrong endpoint, you could end up taking an unhealthy application out of service or restarting it unnecessarily.

5. Don’t Run Too Many Checks at Once

If you have too many checks running at the same time, it can lead to what’s called a “thrashing” effect. This is when the system is constantly trying to keep up with all the checks and ends up getting bogged down, which can impact performance.

To avoid this, it’s important to stagger your health checks so that they’re not all running at the same time. You can do this by setting up different check schedules for different parts of your system. For example, you might have one schedule for database checks and another for application server checks.

By staggering your health checks, you can ensure that they’re all being run regularly without overloading your system.

6. Make Sure Your Containers Are Healthy

If a container is unhealthy, it can cause problems for the entire pod. For example, if a web server container in a pod is unhealthy, it can cause the entire pod to be unavailable. This can have a cascading effect on other pods and services that depend on that pod.

Therefore, it’s important to make sure your containers are healthy before they’re deployed to production. There are a few ways to do this, but one of the most effective is to use a tool like New Relic’s Container Health.

Container Health gives you visibility into the health of your containers in real-time, so you can quickly identify and fix any issues before they cause problems in production.

7. Monitor the Status of Your Pods

Pods are the smallest deployable units in Kubernetes, and each one has a unique IP address. This means that if a pod goes down, all of the applications and services running on that pod will be unavailable.

That’s why it’s so important to monitor the status of your pods and to have a plan in place for what to do if one of them goes down. There are a few different ways to do this, but one of the simplest is to use the kubectl get pods command.

This command will give you the status of all of the pods in your cluster, as well as information about when they were last updated and the current state of each pod.

You can also use this command to get more information about a specific pod, by using the -o wide flag. This will give you information about the node that the pod is running on, as well as the pod’s IP address.

If you see that a pod is in a CrashLoopBackOff state, this means that there is an issue with the container that is preventing it from starting up correctly. In most cases, you’ll need to delete the pod and let Kubernetes recreate it.

8. Monitor the Status of Your Nodes

Nodes are the foundation of any Kubernetes cluster. If a node goes down, it can take your entire application with it. That’s why it’s critical to monitor the health of your nodes and be alerted as soon as one of them starts having problems.

The best way to do this is to use a tool like Prometheus, which is designed specifically for monitoring Kubernetes clusters. Prometheus makes it easy to collect metrics from all of your nodes and then query those metrics to find out if there are any problems.

If you’re not using Prometheus, you can still use the built-in health check API in Kubernetes to get basic information about the health of your nodes. However, this approach requires more manual work to set up and maintain, so it’s not recommended for production environments.

9. Monitor the Status of Your Cluster

A kubernetes cluster is a complex system with many moving parts. To ensure that your applications are running smoothly, it’s important to monitor the status of all the components in your cluster. By doing so, you can identify and fix problems before they cause downtime or data loss.

There are many ways to monitor a kubernetes cluster. The most common method is to use a monitoring tool such as Prometheus. Prometheus is an open-source monitoring tool that is designed specifically for monitoring kubernetes clusters.

Another popular method is to use the kube-state-metrics project. kube-state-metrics is a simple server that collects metrics about the state of kubernetes resources. It can be used to generate dashboards and alerts for your team.

Finally, you can also use the built-in kubernetes dashboard. The dashboard provides a basic overview of the health of your cluster and its resources.

No matter which method you choose, monitoring the status of your kubernetes cluster is essential for keeping your applications running smoothly.

10. Monitor the Status of Your Deployments

The status of a deployment is constantly changing as new pods are created and old ones are deleted. If you’re not monitoring the status of your deployments, it’s easy to miss when something goes wrong.

Kubernetes provides two ways to monitor the status of deployments: the kubectl rollout status command and the Deployment objects themselves.

The kubectl rollout status command gives you a high-level overview of the status of a deployment. It will tell you how many replicas are desired, how many are available, and how many have been updated.

The Deployment object also has a status field that contains information about the deployment. This includes the same information as the kubectl rollout status command, plus information about the latest deployment such as the name, creation timestamp, and strategy.