March 2019
Intermediate to advanced
346 pages
8h 17m
English
Content preview from Cloud Native DevOps with Kubernetes
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Chapter 9. Managing Pods
There are no big problems, there are just a lot of little problems.
Henry Ford
In the previous chapter we covered containers in some detail, and explained how containers are composed to form Pods. There are a few other interesting aspects of Pods, which we’ll turn to in this chapter, including labels, guiding Pod scheduling using node affinities, barring Pods from running on certain nodes with taints and tolerations, keeping Pods together or apart using Pod affinities, and orchestrating applications using Pod controllers such as DaemonSets and StatefulSets.
We’ll also cover some advanced networking options including Ingress resources, Istio, and Envoy.
Labels
You know that Pods (and other Kubernetes resources) can have labels attached to them, and that these play an important role in connecting related resources (for example, sending requests from a Service to the appropriate backends). Let’s take a closer look at labels and selectors in this section.
What Are Labels?
Labels are key/value pairs that are attached to objects, such as pods. Labels are intended to be used to specify identifying attributes of objects that are meaningful and relevant to users, but do not directly imply semantics to the core system.
The Kubernetes documentation
In other words, labels exist to tag resources with information that’s meaningful to us, but they don’t mean anything to Kubernetes. For example, it’s common to label Pods with the application they belong to:
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.