Shulou(Shulou.com)06/01 Report--

Today, I will talk to you about how to learn the Health Check of Kubernetes. Many people may not know much about it. In order to make you understand better, the editor has summarized the following for you. I hope you can get something according to this article.

Health Check

Strong self-healing ability is an important feature of container orchestration engines such as Kubernetes. The default implementation of self-healing is to automatically restart the failed container. In addition, users can also use Liveness and Readiness detection mechanisms to set more detailed health checks to achieve the following requirements:

Zero downtime deployment.

Avoid deploying invalid images.

A more secure rolling upgrade.

Let's learn the Health Check function of Kubernetes through practice.

Default health check

Let's first learn the default health check mechanism of Kubernetes:

Each container starts with a process specified by the CMD or ENTRYPOINT of Dockerfile. If the return code is non-zero when the process exits, the container is considered to have failed and Kubernetes restarts the container based on restartPolicy.

Let's simulate a container failure scenario. The Pod configuration file is as follows:

The restartPolicy for Pod is set to OnFailure, and the default is Always.

Sleep 10; exit 1 simulates a failure 10 seconds after the container starts.

Execute kubectl apply to create a Pod, named healthcheck.

Check the status of Pod in a few minutes:

You can see that the container has been restarted 3 times.

In the above example, the value returned by the container process is non-zero, while Kubernetes believes that the container has failed and needs to be restarted. However, there are many cases in which the failure occurs, but the process does not exit. For example, 500 internal errors are displayed when accessing the Web server, which may be due to system overload or resource deadlock, and the httpd process does not exit abnormally. In this case, restarting the container may be the most direct and effective solution.

After reading the above, do you have any further understanding of how to learn Kubernetes's Health Check? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.