Book Image

Kubernetes for Developers

By : Joseph Heck
Book Image

Kubernetes for Developers

By: Joseph Heck

Overview of this book

Kubernetes is documented and typically approached from the perspective of someone running software that has already been built. Kubernetes may also be used to enhance the development process, enabling more consistent testing and analysis of code to help developers verify not only its correctness, but also its efficiency. This book introduces key Kubernetes concepts, coupled with examples of how to deploy and use them with a bit of Node.js and Python example code, so that you can quickly replicate and use that knowledge. You will begin by setting up Kubernetes to help you develop and package your code. We walk you through the setup and installation process before working with Kubernetes in the development environment. We then delve into concepts such as automating your build process, autonomic computing, debugging, and integration testing. This book covers all the concepts required for a developer to work with Kubernetes. By the end of this book, you will be in a position to use Kubernetes in development ecosystems.
Table of Contents (16 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

CronJob


CronJobs are an extension that build on jobs to allow you to specify a recurring schedule for when they run. The name pulls from a common Linux utility for scheduling recurring scripts called cron. CronJobs were alpha as of Kubernetes version 1.7, and moved to beta in version 1.8, and remain in beta as of version 1.9. Remember that Kubernetes specifications may change, but tend to be fairly solid and have expected utility with beta, so the v1 release of CronJobs may be different, but you can likely expect it to be pretty close to what's available as of this writing.

The specification is highly related to a job, with the primary difference being the kind is CronJob and there is a required field schedule that takes a string representing the timing for running this job.

The format for this string is five numbers, and wildcards can be used. The fields represent:

  • Minute (0–59)
  • Hour (0–23)
  • Day of Month (1–31)
  • Month (1–12)
  • Day of Week (0–6)

A * or? a character can be used in any of these fields...