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Kubernetes
A brief overview of Kubernetes
- Kubernetes is a container orchestration platform designed to automate the deployment, scaling, and management of containerized applications.
- An application gets deployed (encapsulated) into a Pod which is a single instance of an application
- Pods exist on a Node
- Multiple Nodes form a Cluster
- A Kubernetes Deployment file is created in YAML and provides a declarative way to specify the desired state of an application and its associated resources
# A basic Kubernetes deployment file that deploys 2 (replicas) containers
apiVersion: apps/v1
kind: Deployment
metadata:
name: tylers-deployment
labels:
app: tylers-app
spec:
template:
metadata:
name: tylers-pod
lables:
app: tylers-app
spec:
containers:
- name: tylers-container
image: alpine:latest
replicas: 2
selector:
matchLabels:
app: tylers-app
- A handy list of common Kubernetes commands organized by type
# Deploy a container on a Pod
kubectl run <nameOfPod> --image <nameOfTheImageFromYourImageRepo>
# kubectl run nginx --image nginx
# Deploy from a yaml file (apply and create are interchangable)
kubectl apply -f <fileName>.yaml
# Deploy a deployment type file
kubectl apply -f <fileName>.yaml
# View deployment
kubectl get deployments
# Edit a deployment
kubectl edit deployments <deploymentName>
# Apply a new update
kubectl apply -f <fileName>.yaml
# View deployment status
kubectl rollout status deployment/<deploymentName>
# View deployment history
kubectl rollout history deployment/<deploymentName>
# Rollback a deployment
kubectl rollout undo deployment/<deploymentName>
# Get nodes in cluster
kubectl get nodes
# Get OS of running nodes
kubectl get nodes --output wide # other options exist too e.g., json'
# Get Pods
kubectl get pods
# Get details of a Pod
kubectl describe pods # <podName>
# Delete a pod (or pods if more than one is specified)
kubectl delete pod <podName> # <podName2> <podName3>
# Get number of replicasets
kubectl get replicasets
# Get details of replicasets
kubectl describe replicasets # <replicaset name>
# Delete a replicaset (or sets if more than one is specified)
kubectl delete replicasets <replicasetName> # <replicasetName2>
# Edit an existing replicaset (this should take effect after changing the file)
kubectl edit replicasets <replicasetName> # then change the number to replicate
# Create a service
kubectl create -f <serviceDefinitionFile>
# View services
kubectl get serivces
# View pod logs
kubectl logs <podName> -n <namespace>
Last modified 3mo ago