kubetest
Learning how to use Kubernetes using Minikube. ADDENDUM: Also learning Helm.
Resources
Hello Minikube (kubernetes.io)
Running Kubernetes Locally via Minikube (kubernetes.io)
Ingress (kubernetes.io)
Learn Kubernetes in Under 3 Hours: A Detailed Guide to Orchestrating Containers (freecodecamp.org)
Learning Kubernetes: Getting Started with Minikube (sweetcode.io)
Setting up Ingress on Minikube (medium.com)
Quickstart Guide (helm.sh)
Developing Charts (helm.sh)
The Chart Template Developer's Guide (helm.sh)
Chart Development Tips and Tricks (helm.sh)
Terminology
- Pod - the smallest unit of the Kubernetes object model. Typically is a single container, but can be multiple containers that need to share resources.
- Deployment - orchestrates the creation, deletion, and updating of Pods.
- Technically there's an object in between--ReplicaSets--but this is abstracted, and the Kubernetes docs recommend using Deployments in most cases.
- Service - defines a set of Pods (using a Label Selector) and how to access them (e.g. exposing ports). Can be configured as a load balancer.
- Ingress - exposes HTTP(S) routes from outside the cluster to services within the cluster.
Getting Started
Install kubectl, minikube, virtualbox
brew install kubernetes-cli
brew cask install minikube virtualbox
Start minikube in a new VirtualBox instance:
minikube start --vm-driver=virtualbox
Enable some addons:
minikube addons enable ingress
minikube addons enable registry-creds
Add an entry to /etc/hosts for ingress:
# IP of minikube vm (use `minikube ip`)
192.168.99.101 kube.test
Helpful Commands
Open a minikube dashboard to visually inspect the cluster:
minikube dashboard
Open a service in the browser (not sure what happens if there are multiple ports defined):
minikube service xxx
Kill the minikube vm:
minikube stop
Submitting a specification to the cluster:
kubectl create -f xxx.yaml
Updating an existing specification:
kubectl apply -f xxx.yaml
Deleting a specification:
kubectl delete pod xxx
kubectl delete svc xxx
kubectl delete deployment xxx
kubectl delete ing xxx
Inspecting pods, deployments, and services in the cluster:
kubectl get pod
kubectl describe pod xxx
kubectl get svc
kubectl describe svc xxx
kubectl get deployments
kubectl describe deployments.apps xxx
kubectl get ingress
kubectl describe ing xxx
Creating a port-forward to a specific Pod (could be handy for testing):
kubectl port-forward xxx 8080:80
# ports are [pod]:[host]
Zero-downtime deployment / rollback:
kubectl apply -f xxx.yaml --record
kubectl rollout status deployment xxx
# rollback
kubectl rollout history deployment xxx
kubectl rollout undo deployment xxx --to-revision=N
Using local docker images:
eval $(minikube docker-env)
# AFAIK submitting an unchanged spec is a no-op, so I've been incrementing a version tag for every build
docker build -t xxx:v1 .
# use the tag in the pod/deployment spec
Tailing logs from multiple pods using kubetail:
kubetail xxx