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.

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Table of Contents (16 chapters)
Title Page
Title Page
Packt Upsell
Packt Upsell
Contributors
Contributors
Preface
Preface
Free Chapter
1
Setting Up Kubernetes for Development
Setting Up Kubernetes for Development
What you need for development
Getting a local cluster up and running
Resetting and restarting your cluster
Looking at what's built-in and included with Minikube
Verifying Docker
Clearing and cleaning Docker images
Kubernetes concept – container
Kubernetes resource – Pod
Kubernetes resource – Node
Kubernetes resource – ReplicaSet
Kubernetes resource – Deployment
Summary
2
Packaging Your Code to Run in Kubernetes
Packaging Your Code to Run in Kubernetes
Container images
Making your first container
Example – Python/Flask container image
Example – Node.js/Express container image
Tagging your container images
Summary
3
Interacting with Your Code in Kubernetes
Interacting with Your Code in Kubernetes
Practical notes for writing software to run in a container
Logs
More debugging techniques
Kubernetes concepts – labels
Kubernetes concepts – selectors
Kubernetes resources – service
Discovering services from within your Pod
Exposing services outside the cluster
Example service – Redis
Deployments and rollouts
Summary
4
Declarative Infrastructure
Declarative Infrastructure
Imperative versus declarative commands
Declaring your first application
Kubernetes resource – Annotations
Kubernetes resource – ConfigMap
Kubernetes resource – Secrets
Example – Python/Flask deployment with ConfigMap
Summary
5
Pod and Container Lifecycles
Pod and Container Lifecycles
Pod lifecycle
Probes 
Container lifecycle hooks
Initialization containers
Handling a graceful shutdown
Summary
6
Background Processing in Kubernetes
Background Processing in Kubernetes
Job
CronJob
A worker queue example with Python and Celery
Persistence with Kubernetes
Stateful Sets
Custom Resource Definition
Summary
7
Monitoring and Metrics
Monitoring and Metrics
Built-in metrics with Kubernetes
Kubernetes concept – Quality of Service
Capturing metrics with Prometheus
Installing Grafana
Using Prometheus to view application metrics
Summary
8
Logging and Tracing
Logging and Tracing
A Kubernetes concept – DaemonSet
Installing and using Elasticsearch, Fluentd, and Kibana
Viewing logs using Kibana
Distributed tracing with Jaeger
Example – adding tracing to your application
Summary
9
Integration Testing
Integration Testing
Testing strategies using Kubernetes
Simple validation with Bats
Example – integration testing with Python
Example – integration testing with Node.js
Continuous integration with Kubernetes
Summary
10
Troubleshooting Common Problems and Next Steps
Troubleshooting Common Problems and Next Steps
Common errors and how to resolve them
Emerging projects for developers
Interacting with the Kubernetes project
Summary
Other Books You May Enjoy
Other Books You May Enjoy
Leave a review - let other readers know what you think
Index
Index

Deployments and rollouts

Changing the image within a deployment initiates a rollout. A deployment rollout is an asynchronous process that takes time to complete, and is controlled by values defined within the deployment. If you look at the resource file that we dumped into YAML and updated, you will see the defaults that were created for the deployment when we made it with the kubectl run command.

Under spec -> strategy, you will see the default specification of how it will handle an update:

  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
    type: RollingUpdate

As of Kubernetes 1.8, there are two strategies available: Recreate and RollingUpdate. RollingUpdate is the default, and is intended for the primary use case of maintaining service availability while doing code updates. Recreate operates differently: killing all existing pods before creating new pods with updated versions, which may result in a short outage.

The RollingUpdate is controlled by two values: maxUnavailable...

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