Learning-Kubernetes

This project aims to learn Kubernetes to prepare for the CKA certification and CKAD certification based on a local cluster consisting of virtual machines.

Prerequisites:

• Linux CLI skills
• vi/nano as editor for yaml files
• grep/awk/head/tail/cat for providing output from commands
• scp for copying files from one server to another
• tmux for running commands on more than one server at a time
• systemd/journalctl for debugging clusters and changing systemd unit files etc.
• experience with docker to run standard containers, used commands to keep docker containers running, understanding images, tags etc.

Resources

Links and Tutorials

• https://kubernetes.io/docs/
• https://kubernetes.io/docs/tasks/
• https://github.com/kelseyhightower/kubernetes-the-hard-way
• https://github.com/cncf/curriculum

Udemy

• https://github.com/kodekloudhub/certified-kubernetes-administrator-course

CKA

The Udemy course Certified Kubernetes Administrator with practice tests is also used in terms of understanding Kubernetes and preparation for the certification.

CKAD

Topic in CKAD

• multi-container pods design patterns
  • ambassador pattern
  • adapter pattern
• Self-healing applications
  • self-healing applications through ReplicaSets and Replication Controllers
  • Replication Controller: ensures that pod is recreates automatically and ensures that enough replicas are running at all times
  • Liveness and Readiness Probes
• Storage
  • StatefulSets
• Service Accounts

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Kubernetes Command Line Tools

kubectx

• tool to switch contexts between clusters in a multi-cluster environment
• installation

sudo git clone https://github.com/ahmetb/kubectx /opt/kubectx
sudo ln -s /opt/kubectx/kubectx /usr/local/bin/kubectx

• to list all contexts

kubectx

• to switch to a new context

kubectx <context_name>

• switch back to previous context

kubectx -

• to see the current context

kubectx -c

kubens

• toll allowing users to switch between namespaces with a simple command
• installation

sudo git clone https://github.com/ahmetb/kubectx /opt/kubectx
sudo ln -s /opt/kubectx/kubens /usr/local/bin/kubens

• to switch to a namespace

kubens <new_namespaces>

• to switch back to previous namespace

kubens -

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Cluster Architecture Setup

• which VMs?
• what network in VirtualBox?
• what servers to use?
• ...

Learning and Understanding Kubernetes

• install container runtimes on cluster servers
• setting up local cluster
• setup network tool for kubernetes
• ...