Kubernetes Commands: Cluster Nodes, Namespaces, LimitRange Resource Limits, Pods, Deployments, Replication Controllers, Services, HPA, Secrets, Cronjobs, Helm, Logs, K9s TUI

Table of Contents

Kubernetes-Components - This article is part of a series.

Part 1: Rancher Kubernetes Management Platform: Cert Manager Helm Deployment, Rancher Helm Deployment with Rancher CA certificate, Export Root CA Certificate, Ingress Resource, Access Rancher with TLS Encryption

Part 2: Velero Open-Source Kubernetes Backups: Velero Helm Deployment, Backup and Restore a Kubernetes Namespace from an AWS S3 Bucket

Part 3: Kubernetes Deployment Components: Pods - Multi Container Pod Example, Container Networking Within a Pod; Replication Controller; Services - ClusterIP, NodePort & LoadBalancer Services, Services for Pods, Replication Controllers, External Resources & Deployments

Part 4: Kubernetes Resource Management: Define Resource Requests and Limits; Deploy Kubernetes Metrics Server, Verify Resource Usage with kubectl top

Part 5: Kubernetes Security: Immutable Deployment - Deploy Container with ReadOnly-Filesystem and Writable-Volume

Part 6: Kubernetes Security: Pod Security Admission (PSA) - Overview, Enforce Pod Security Standard at a Namespace; Example Nginx Pod SecurityContext for Restricted PSS

Part 7: Kubernetes Volumes: Nginx Pod and Deployment Examples with NFS Volume, Pod and Deployment Examples with EmptyDir Volume, Deployment Example with PersistentVolume, External Storage Provider with NFS

Part 8: Kubernetes Secrets: Opaque Secret Configuration, Pod Examples with Environment Variable Secrets and Volume Secrets; SSH Authentication Secret with Pod Example

Part 9: Kubernetes Horizontal Pod Autoscaling: Install Kubernetes Metrics Server, Example Deployment with Horizontal Pod Autoscaler (HPA)

Part 10: Kubernetes DNS: CoreDNS custom Hosts entry (K3s & K8s Version), Deployment with custom Hosts entry; Backup and Restore the CoreDNS ConfigMap; DNS Troubleshooting

Part 11: Kubernetes Liveness & Readiness Probes: TCP Readiness Probes (Single Pod and Multi Pod Dependency), TCP Liveness Probe

Part 12: Kubernetes Network Policies: Ingress and Egress Policy Examples

Part 13: Kubernetes Role Based Access Control (RBAC): RBAC Overview, Create Service Account, Example Role and RoleBinding

Part 14: Kubernetes Kubeconfig: Create example Kubeconfig with new (RBAC) Service Account and ClusterRole / ClusterRole Binding

Part 15: Kubernetes Container Storage Interface (CSI): NFS CSI Driver Example, Dynamically create PersistentVolumes using a CSI StorageClass and PVC

Part 16: Kubernetes Container Storage Interface (CSI): Ceph CSI Driver Example, Dynamically provision RBD Images in a Ceph Storage Pool

Part 17: Kubernetes Container Storage Interface (CSI): Longhorn Distributed Block Storage System - Deploy Longhorn via Helm Chart, Define Custom Storage Mountpoints; StorageClass & PVC Example

Part 18: Kubernetes Container Storage Interface (CSI): Samba - Deploy SMB CSI via Helm, Create example PVC and Pod

Part 19: Kubernetes Etcd Snapshot: Etcd Snapshot and Restore with Etcdctl, Verify Etcd Member Health; Etcdctl Commands

Part 20: Kubernetes Helm Charts: Create a Custom Helm Chart

Part 21: Kubernetes Kustomize: Kustomize Configuration Management Example

Part 22: Kubernetes ReplicaSets & DaemonSets: Overview, Example ReplicaSets and DaemonSets with and without NodeSelector & Node Labeling

Part 23: Kubernetes Jobs: Jobs Overview, Basic Non-parallel & Parallel Job Examples; CronJob & RBAC Example that Restarts a Deployment

Part 24: This Article

Help
#

# List kubectl commands
kubectl -h

# List help for specific command: "get" command
kubectl get -h

Cluster Nodes
#

List Nodes & Check Cluster Status
#

# List nodes
kubectl get nodes

# List nodes: More details
kubectl get nodes -o wide

# Shell output: Example
NAME    STATUS   ROLES           AGE   VERSION   INTERNAL-IP     EXTERNAL-IP   OS-IMAGE                         KERNEL-VERSION   CONTAINER-RUNTIME
node1   Ready    control-plane   27h   v1.29.5   192.168.30.71   <none>        Debian GNU/Linux 12 (bookworm)   6.1.0-21-amd64   containerd://1.7.16
node2   Ready    control-plane   27h   v1.29.5   192.168.30.72   <none>        Debian GNU/Linux 12 (bookworm)   6.1.0-21-amd64   containerd://1.7.16
node3   Ready    worker          27h   v1.29.5   192.168.30.73   <none>        Debian GNU/Linux 12 (bookworm)   6.1.0-21-amd64   containerd://1.7.16
node4   Ready    worker          27h   v1.29.5   192.168.30.74   <none>        Debian GNU/Linux 12 (bookworm)   6.1.0-21-amd64   containerd://1.7.16

Label Worker Nodes
#

# Label a worker node
kubectl label nodes <node-name> kubernetes.io/role=worker

Kubelet Logs
#

# List Kubelet logs of a Kubernetes Node: Run on desired node
sudo journalctl -u kubelet

Kubernetes Version
#

# List Kubernetes version: Client (Kubectl) & Server (Kubernetes Cluster)
kubectl version

Shutdown Node / Maintenance Mode
#

# drain each node, which safely evicts all pods from the node in preparation for maintenance
kubectl drain node3 --ignore-daemonsets --delete-emptydir-data

# Verify the status
kubectl get nodes

# Shell output
NAME    STATUS                     ROLES           AGE    VERSION
node1   Ready                      control-plane   6d1h   v1.29.5
node2   Ready                      control-plane   6d1h   v1.29.5
node3   Ready,SchedulingDisabled   <none>          6d1h   v1.29.5
node4   Ready,SchedulingDisabled   <none>          6d1h   v1.29.5

# Uncord node / mark it as schedulable
kubectl uncordon node3

# Verify the status
kubectl get nodes

# Shell output
NAME    STATUS   ROLES           AGE    VERSION
node1   Ready    control-plane   6d1h   v1.29.5
node2   Ready    control-plane   6d1h   v1.29.5
node3   Ready    <none>          6d1h   v1.29.5
node4   Ready    <none>          6d1h   v1.29.5

Namespaces
#

Default Namespaces
#

default All Kubernetes objects created without a specified namespace will be put into the “default” namespace.
kube-system Kubernetes system objects

List Namespaces
#

# List all namespaces
kubectl get namespaces

# List all namespaces: Short version
kubectl get ns

Create Namespace
#

Create Namespace with CLI
#

# Create a new namespace
kubectl create namespace namespace-name

Create Namespace with YAML Configuration
#

# Create a namespace configuration
vi new-namespace.yaml

apiVersion: v1
kind: Namespace
metadata:
  name: new-namespace

# Deploy the namespace
kubectl create -f new-namespace.yaml

List Namespace Details
#

# List namespace details
kubectl describe namespace new-namespace

Delete Namespace
#

# Delete the namespace "new-namespace"
kubectl delete namespace new-namespace

Create Resources in specific Namespace
#

# Create pod: In specific namespace
kubectl run pod-name --image=image-name --namespace namespace-name

# Deploy a resource in a specific namespace
kubectl create -f filename.yaml --namespace namespace-name

Note: Use either --namespace or just -n to define a namespace.

List Resources in specific Namespace
#

Specific Resource Type
#

# List pods: In specific namespace
kubectl get pods --namespace namespace-name

# List deployments: In specific namespace
kubectl get deployments --namespace namespace-name

# List services: In specific namespace
kubectl get services --namespace namespace-name

All Resources
#

# List all resources: In specific namespace
kubectl get all -n namespace-name

Delete Resource in specific Namespace
#

# Delete pod: In specific namespace
kubectl delete pod pod-name --namespace new-namespace

# Delete deployment: In specific namespace
kubectl delete deployment deployment-name --namespace namespace-name

# Delete serice: In specific namespace
kubectl delete service service-name --namespace namespace-name

Switch the Default Namespace
#

List Current Cluster
#

# List the current kubectl context: Cluster & user
kubectl config view | grep current-context

# Shell output:
current-context: kubernetes-admin@k8s.jkw.local

Set new Default Namespace
#

# Set the namespace "new-namespace" as the default namespace
kubectl config set-context kubernetes-admin@k8s.jkw.local --namespace new-namespace

# Set the namespace "default" as the default namespace
kubectl config set-context kubernetes-admin@k8s.jkw.local --namespace default

Verify the default Namespace
#

# Verify the configuration
kubectl config view

# Shell output:
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: https://127.0.0.1:6443
  name: k8s.jkw.local
contexts:
- context:
    cluster: k8s.jkw.local
    namespace: new-namespace # Default namespace
    user: kubernetes-admin
  name: kubernetes-admin@k8s.jkw.local
current-context: kubernetes-admin@k8s.jkw.local
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: DATA+OMITTED
    client-key-data: DATA+OMITTED

LimitRange Resource Limits
#

Create LimitRange Resource
#

# Create a LimitRange configuration
vi namespace-limits.yaml

apiVersion: v1
kind: LimitRange
metadata:
  name: example-namespace-limits
  namespace: example-namespace
spec:
  limits:
  - type: Pod
    max:
      cpu: "2"
      memory: "1Gi"
    min:
      cpu: "200m"
      memory: "100Mi"
  - type: Container
    default:
      memory: "300Mi"
      cpu: "200m"
    defaultRequest:
      memory: "200Mi"
      cpu: "100m"
    max:
      memory: "600Mi"
      cpu: "400m"
    min:
      memory: "100Mi"
      cpu: "100m"

# Deploy the LimitRange resource
kubectl create -f namespace-limits.yaml

List LimitRange Resources
#

# List the LimitRange resource for the namespace
kubectl get LimitRange --namespace example-namespace

# Shell output:
NAME                       CREATED AT
example-namespace-limits   2024-06-01T11:33:15Z

List Namespace Resource Limits
#

# List the namespace details
kubectl describe namespace example-namespace

# Shell output:
Name:         example-namespace
Labels:       kubernetes.io/metadata.name=example-namespace
Annotations:  <none>
Status:       Active

No resource quota.

Resource Limits
 Type       Resource  Min    Max    Default Request  Default Limit  Max Limit/Request Ratio
 ----       --------  ---    ---    ---------------  -------------  -----------------------
 Pod        cpu       200m   2      -                -              -
 Pod        memory    100Mi  1Gi    -                -              -
 Container  memory    100Mi  600Mi  200Mi            300Mi          -
 Container  cpu       100m   400m   100m             200m           -

Delete LimitRange Resource
#

# Delete the LimitRange resource
kubectl delete LimitRange example-namespace-limits --namespace example-namespace

YAML Manifest / Configuration
#

Deploy Resources from YAML Config
#

# Deploy resources from YAML configuration: Current namespace
kubectl create -f filename.yaml

# Deploy resources from YAML configuration: Specific namespace
kubectl create -f filename.yaml -n namespace-name

Update Resources from YAML Config
#

# Deploy resources updates from YAML configuration: Current namespace
kubectl apply -f filename.yaml

# Deploy resources updates from YAML configuration: Specific namespace
kubectl apply -f filename.yaml -n namespace-name

Delete Resources from YAML Config
#

# Delete resources from YAML configuration: Current namespace
kubectl delete -f filename.yaml

# Delete resources from YAML configuration: Specific namespace
kubectl delete -f filename.yaml

Create YAML Manifest from Deployment
#

# Save YAML Manifest from existing deployment: Current namespace
kubectl get deployment-type deployment-name -o yaml > filename.yaml

# Save YAML Manifest from existing deployment: Specific namespace
kubectl get deployment-type deployment-name -n namespace-name -o yaml > filename.yaml

Example: Backup & Restore Deployment
#

This is an example for CoreDNS deployment backup and restore:

# Create a backup of a Deployment
kubectl get deployment coredns -n kube-system -o yaml > coredns-deployment.yaml

# Delete the Deployment
kubectl delete deployment coredns -n kube-system

# Restore the Deployment
kubectl apply -f coredns-deployment.yaml

Pods
#

List Pods
#

List Pods:

# List pods
kubectl get pod

# List pods: More details like node name
kubectl get pods -o wide

Watch Pods:

# # List pods: Watch the status change
kubectl get pods --watch

List Pods per Label:

# List pods: With specific label "nginx"
kubectl get pod -l app=nginx

List Pods, define Namespace:

# List pods: In specific namespace
kubectl get pods --namespace=namespace-name

# List pods: In all namespaces
kubectl get pods --all-namespaces

List Pod Details
#

# List pod details
kubectl describe pod <pod-name>

Delete Pod
#

# Delete pod
kubectl delete pod <pod-name>

Pods / Containers
#

Container Shell
#

# Access an container shell: Single container pod
kubectl exec -it pod-name -- /bin/bash

# Access an container shell: Multi container pod
kubectl exec -it pod-name -c container-name -- /bin/bash

Container Environment Variables
#

# List environment variables: Single container pod
kubectl exec pod-name -- printenv

# List environment variables: Multi container pod
kubectl exec pod-name -c container-name -- printenv

Container Logs
#

# Container logs: Single container pod
kubectl logs my-pod

# Container logs: Multi container pod
kubectl logs pod-name -c container-name

Container Port Forwarding
#

Kubernetes will forward to the correct container based on the destination port:

# Forward container port: Local access
kubectl port-forward pod-name 8080:80

# Forward container port: Local access, specific namespace
kubectl port-forward pod-name -n namespace-name 8080:80

# Forward container port: Access from other hosts
kubectl port-forward --address 0.0.0.0 pod-name 8080:80

# Forward container port: Access from other hosts, specific namespace
kubectl port-forward --address 0.0.0.0 pod-name -n namespace-name 8080:80

# Curl the local port
curl localhost:8080

# Stop port forwarding
Strg + C

Deployments
#

List Deployments
#

# List deployments
kubectl get deployments

List Deployment Details
#

# List deployment details
kubectl describe deployment <deployment-name>

Scale Deployment
#

# Set the number of replicas for a deployment 
kubectl scale deployment <deployment-name> --replicas=2

Delete Deployment
#

# Delete deployment
kubectl delete deployment <deployment-name>

Replication Controllers
#

List RC
#

# List Replication Controllers
kubectl get rc
kubectl describe rc controller-name

List RC Details
#

# List Replication Controller details
kubectl describe rc controller-name

Edit RC
#

# Edit Replcation Controller
kubectl edit rc/controller-name

Delete RC
#

# Delete the replication controller and it's pods
kubectl delete rc controller-name

Services
#

Service Types
#

ClusterIP Default service type when no service type is defined
--type=NodePort Creates a NodePort service
--type=LoadBalancer Creates a LoadBalancer service

Access NodePort
#

NAME          TYPE        CLUSTER-IP     EXTERNAL-IP      PORT(S)          AGE
testservice   NodePort    10.233.13.17   192.168.30.100   8000:32007/TCP   2s

A NodePort service exposes a static port (NodePort) randomly assigned, in this example port “32007” on all nodes external IPs in the cluster, and internal on the cluster IP, in this example on port “8000”. Optional an external IP can be defined.

Create Service
#

Service for Deployment
#

ClusterIP Service:

# Create service type "ClusterIP" for a deployment
kubectl expose deployment <deployment-name> --port=8000 --target-port=80 --name=<service-name>

# Create service type "ClusterIP" for a deployment: Add external IP to access the service
kubectl expose deployment <deployment-name> --port=8000 --target-port=80 --name=<service-name> --external-ip="192.168.30.100"

NodePort Service:

# Create service type "NodePort" for a deployment
kubectl expose deployment <deployment-name> --type=NodePort --port=8000 --target-port=80 --name=<service-name>

# Create service type "NodePort" for a deployment: Add external IP to access the service
kubectl expose deployment <deployment-name> --type=NodePort --port=8000 --target-port=80 --name=<service-name> --external-ip="192.168.30.100"

LoadBalancer Service:

# Create service type "LoadBalancer" for a deployment: Random LoadBalancer IP
kubectl expose deployment <deployment-name> --type=LoadBalancer --port=8000 --target-port=80 --name=<service-name>

# Create service type "LoadBalancer" for a deployment: Define a specific LoadBalancer IP
kubectl expose deployment <deployment-name> --type=LoadBalancer --port=8000 --target-port=80 --name=<service-name> --external-ip="192.168.30.111"

Service for Pod
#

# Create service type "ClusterIP" for a pod
kubectl expose pod <pod-name> --port=8000 --target-port=80 --name=<service-name>

# Create service type "ClusterIP" for a pod: Add external IP to access the service
kubectl expose pod <pod-name> --port=8000 --target-port=80 --name=<service-name> --external-ip="192.168.30.100"

Service for Replication Controller
#

# Create service type "ClusterIP" for a Replication Controller
kubectl expose rc <rc-name> --port=8000 --target-port=80 --name=<service-name>

# Create service type "ClusterIP" for a Replication Controller: Add external IP to access the service
kubectl expose rc <rc-name> --port=8000 --target-port=80 --name=<service-name> --external-ip="192.168.30.100"

List Services
#

# List all services / service details
kubectl get svc

List Service Details
#

# List service details
kubectl get svc <service-name>

# List more service details
kubectl describe svc <service-name>

Delete Service
#

# Delete service
kubectl delete service <service-name>

StorageClass, PV, PVC
#

StorageClasses
#

# List storage clases
kubectl get storageclasses

# Delete storage class
kubectl delete storageclass storageclass-name

Persistent Volume Claims
#

# List PVC
kubectl get pvc

# Delete PVC
kubectl delete pvc pvc-name

Persistent Volumes
#

# List PV
kubectl get pv

# Delete PV

kubectl delete pv pv-name

Horizontal Pod Autoscaler (HPA)
#

Deploy HPA
#

# Deploy a pod autoscaler: Maintains between 1 and 10 pod replicas
kubectl autoscale deployment deployment-name --cpu-percent=50 --min=1 --max=10 --name=hpa-name

List & Watch HPA / Check Status
#

# List the HPA status: Wait till the HPA gets a target output from the metrics server
kubectl get hpa

# Wacht the load of the HPA
kubectl get hpa hpa-name --watch

List HPA Details
#

# List HPA details
kubectl describe hpa hpa-name

Delete HPA
#

# Wacht the HPA
kubectl delete hpa hpa-name

ConfigMaps
#

List ConfigMaps
#

# List ConfigMaps: In current namespace
kubectl get cm

# List ConfigMaps: In all namespace
kubectl get cm --all-namespaces

# List ConfigMaps: In specific namespace
kubectl get cm -n namespacename

Edit ConfigMap
#

# Edit ConfigMap: Corrent namespace
kubectl edit cm configmap-name

# Edit ConfigMap: Specific namespace
kubectl edit cm configmap-name -n namespace-name

List ConfigMap Details
#

# List ConfigMap details: Corrent namespace
kubectl describe cm configmap-name

# List ConfigMap details: Specific namespace
kubectl describe cm configmap-name -n namespace-name

Delete ConfigMap
#

# Delete ConfigMap: Corrent namespace
kubectl delete cm configmap-name

# Delete ConfigMap: Specific namespace
kubectl delete cm configmap-name -n namespace-name

Secrets
#

List Secrets
#

# List secrets
kubectl get secrets

Secret Details
#

# List secret details
kubectl describe secret secret-name

Delete Secret
#

# Delete secret
kubectl delete secret secret-name

Network Policies
#

List Network Policy
#

# List network policy: Describe all NetworkPolicies in "default" namespace
kubectl describe networkpolicy 

# List network policy: Describe specific "network-policy-ex-pods" np in "default" namespace
kubectl describe networkpolicy networkpolicy-name -n default

Delete Network Policy
#

# Delete network policy
kubectl delete networkpolicy networkpolicy-name

Cronjobs
#

YAML Configuration Example
#

# Create cronjob configuration
vi example-conjob.yaml

apiVersion: batch/v1
kind: CronJob
metadata:
  name: example-cronjob
spec:
  schedule: "*/1 * * * *"
  jobTemplate: # Defines the job to be created on each schedule occurrence
    spec:
      template: # The Pod template
        spec:
          containers:
          - name: cronjob-container
            image: busybox
            args:
            - /bin/sh
            - -c
            - date; echo Hello from the Kubernetes cluster
          restartPolicy: OnFailure

# Deploy cronjob
kubectl apply -f example-conjob.yaml

List Cronjobs
#

Example Details:

# List cronjobs
kubectl get cronjobs

# Shell output:
NAME               SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
example-cronjob    */1 * * * *   False     0        16s             40s

SUSPEND = False CronJob is active and will trigger executions according to its defined schedule
SUSPEND = True CronJob is currently suspended, and no new jobs will be started until it is unsuspended

Command Overview:

# List cronjobs: In current namespace
kubectl get cronjobs

# List cronjobs: In a specific namespace
kubectl get cronjobs -n namespace-name

# List cronjobs: In all namespaces
kubectl get cronjobs --all-namespaces

Suspend & Resume Conjob
#

Example Details:

# Suspend cronjob: Example
kubectl patch cronjob example-cronjob -p '{"spec":{"suspend": true}}'

# Verify the cronjob status
kubectl get cronjobs

# Shell output:
NAME               SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
example-cronjob    */1 * * * *   True      0        43s             67s

# Resume cronjob: Example
kubectl patch cronjob example-cronjob -p '{"spec":{"suspend": false}}'

Command Overview:

# Suspend cronjob: Syntax
kubectl patch cronjob cronjob-name -p '{"spec":{"suspend": true}}'

# Resume cronjob: Syntax
kubectl patch cronjob cronjob-name -p '{"spec":{"suspend": false}}'

Check Job Execution
#

# List jobs
kubectl get jobs

# Shell output:
NAME                        COMPLETIONS   DURATION   AGE
example-cronjob-28621260   1/1           5s         4m56s
example-cronjob-28621264   1/1           5s         49s

List Cronjob Details
#

# List cronjobs: In current namespace
kubectl describe cronjob cronjob-name

# List cronjobs: In a specific namespace
kubectl describe cronjob cronjob-name -n namespace-name

Delete Cronjob
#

# Delete cronjob: In current namespace
kubectl delete cronjob cronjob-name 

# Delete cronjob: In a specific namespace
kubectl delete cronjob cronjob-name -n namespace-name

Helm
#

Install Helm
#

# Install Helm with script
curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 &&
chmod +x get_helm.sh &&
./get_helm.sh

# Verify the installation / check version
helm version

Repositories
#

Add Repository
#

# Add repository
helm repo add repo-alias https://repo-url

Update Repository Index
#

# Update package index
helm repo update

List Repositories
#

# List repositories
helm repo list

Remove Repository
#

# Remove repository
helm repo remove repo-alias

Charts / Packages
#

List Available Charts in Repository
#

# List available charts in the Helm repository
helm search repo repo-alias

Install Package
#

# Install package: Syntax
helm install release-name repo-alias/chart-name

# For example
helm install metrics-server metrics-server/metrics-server

release-name Chosen name for the Helm installation within the Kubernetes cluster
repo-alias Alias that was defined for the repository
chart-name # Package you want to install from the repository

Uninstall Package
#

# Uninstall package: Current namespace
helm uninstall release-name

# Uninstall package: Specific namespace
helm delete velero -n namespace-name

List Installed Packages
#

# List Helm releases in the `namespace-name` namespace
helm ls -n namespace-name

# List Helm releases across all namespaces
helm ls --all-namespaces

Download Helm Chart
#

# Download & untar a Helm chart
helm pull repo-alias/chart-name --untar

Logs
#

Pod Logs
#

Single Container
#

# List the logs of a pod: Single container pod, current namespace
kubectl logs pod-name

# List the logs of a pod: Single container pod, specific namespace
kubectl logs pod-name -n namespace-name

Multi Container
#

# List the logs of a pod: Multi container pod, current namespace
kubectl logs pod-name -c container-name

# List the logs of a pod: Multi container pod, specific namespace
kubectl logs pod-name -c container-name -n namespace-name

Specific Time
#

# Logs from the last 5 minutes: Current namespace
kubectl logs pod-name --since=5m

# Logs from the last 5 minutes: Specific namespace
kubectl logs pod-name --since=5m -n namespace-name


# Logs from the last 24 hours: Current namespace
kubectl logs pod-name --since=24h

# Logs from the last 24 hours: Specific namespace
kubectl logs pod-name --since=24h -n namespace-name

Watch Real-time Logs
#

# Real-time logs from all containers in a pod: Current namespace
kubectl logs -f --all-containers=true pod-name

# Real-time logs from all containers in a pod: Specific namespace
kubectl logs -f --all-containers=true pod-name -n namespace-name

Troubleshooting
#

Pod for Network Troubleshooting
#

# Run pod for network troubleshooting 
kubectl run busybox --image=busybox --restart=Never --stdin --tty

# Run commands
nslookup example.com
ping example.com

# Delete pod
kubectl delete pod busybox

Utilities
#

K9s
#

Install K9s
#

Find latest release:
https://github.com/derailed/k9s/tags

# Download package (Debian based)
wget https://github.com/derailed/k9s/releases/download/v0.32.5/k9s_linux_amd64.deb

# Install package
sudo dpkg -i k9s_linux_amd64.deb

# Install missing dependencies
sudo apt install -f

Verify K9s Installation
#

# Verify installation / check version
k9s version

Start K9s
#

# Start k9s
k9s

# Exit k9s
Strg + C

K9s Commands
#

# List nodes
:node

# List namespaces
:ns

# List deployments
:deploy

# List pods
:pod

# List services
:svc

# Go back
ESC

# List logs
l

Kubernetes-Components - This article is part of a series.

Part 2: Velero Open-Source Kubernetes Backups: Velero Helm Deployment, Backup and Restore a Kubernetes Namespace from an AWS S3 Bucket

Part 4: Kubernetes Resource Management: Define Resource Requests and Limits; Deploy Kubernetes Metrics Server, Verify Resource Usage with kubectl top

Part 5: Kubernetes Security: Immutable Deployment - Deploy Container with ReadOnly-Filesystem and Writable-Volume

Part 6: Kubernetes Security: Pod Security Admission (PSA) - Overview, Enforce Pod Security Standard at a Namespace; Example Nginx Pod SecurityContext for Restricted PSS

Part 8: Kubernetes Secrets: Opaque Secret Configuration, Pod Examples with Environment Variable Secrets and Volume Secrets; SSH Authentication Secret with Pod Example

Part 9: Kubernetes Horizontal Pod Autoscaling: Install Kubernetes Metrics Server, Example Deployment with Horizontal Pod Autoscaler (HPA)

Part 10: Kubernetes DNS: CoreDNS custom Hosts entry (K3s & K8s Version), Deployment with custom Hosts entry; Backup and Restore the CoreDNS ConfigMap; DNS Troubleshooting

Part 11: Kubernetes Liveness & Readiness Probes: TCP Readiness Probes (Single Pod and Multi Pod Dependency), TCP Liveness Probe

Part 12: Kubernetes Network Policies: Ingress and Egress Policy Examples

Part 13: Kubernetes Role Based Access Control (RBAC): RBAC Overview, Create Service Account, Example Role and RoleBinding

Part 14: Kubernetes Kubeconfig: Create example Kubeconfig with new (RBAC) Service Account and ClusterRole / ClusterRole Binding

Part 15: Kubernetes Container Storage Interface (CSI): NFS CSI Driver Example, Dynamically create PersistentVolumes using a CSI StorageClass and PVC

Part 16: Kubernetes Container Storage Interface (CSI): Ceph CSI Driver Example, Dynamically provision RBD Images in a Ceph Storage Pool

Part 17: Kubernetes Container Storage Interface (CSI): Longhorn Distributed Block Storage System - Deploy Longhorn via Helm Chart, Define Custom Storage Mountpoints; StorageClass & PVC Example

Part 18: Kubernetes Container Storage Interface (CSI): Samba - Deploy SMB CSI via Helm, Create example PVC and Pod

Part 19: Kubernetes Etcd Snapshot: Etcd Snapshot and Restore with Etcdctl, Verify Etcd Member Health; Etcdctl Commands

Part 20: Kubernetes Helm Charts: Create a Custom Helm Chart

Part 21: Kubernetes Kustomize: Kustomize Configuration Management Example

Part 22: Kubernetes ReplicaSets & DaemonSets: Overview, Example ReplicaSets and DaemonSets with and without NodeSelector & Node Labeling

Part 23: Kubernetes Jobs: Jobs Overview, Basic Non-parallel & Parallel Job Examples; CronJob & RBAC Example that Restarts a Deployment

Part 24: This Article

Help #

Cluster Nodes #

List Nodes & Check Cluster Status #

Label Worker Nodes #

Kubelet Logs #

Kubernetes Version #

Shutdown Node / Maintenance Mode #

Namespaces #

Default Namespaces #

List Namespaces #

Create Namespace #

Create Namespace with CLI #

Create Namespace with YAML Configuration #

List Namespace Details #

Delete Namespace #

Create Resources in specific Namespace #

List Resources in specific Namespace #

Specific Resource Type #

All Resources #

Delete Resource in specific Namespace #

Switch the Default Namespace #

List Current Cluster #

Set new Default Namespace #

Verify the default Namespace #

LimitRange Resource Limits #

Create LimitRange Resource #

List LimitRange Resources #

List Namespace Resource Limits #

Delete LimitRange Resource #

YAML Manifest / Configuration #

Deploy Resources from YAML Config #

Update Resources from YAML Config #

Delete Resources from YAML Config #

Create YAML Manifest from Deployment #

Example: Backup & Restore Deployment #

Pods #

List Pods #

List Pod Details #

Delete Pod #

Pods / Containers #

Container Shell #

Container Environment Variables #

Container Logs #

Container Port Forwarding #

Deployments #

List Deployments #

List Deployment Details #

Scale Deployment #

Delete Deployment #

Replication Controllers #

List RC #

List RC Details #

Edit RC #

Delete RC #

Services #

Service Types #

Access NodePort #

Create Service #

Service for Deployment #

Service for Pod #

Service for Replication Controller #

List Services #

List Service Details #

Delete Service #

StorageClass, PV, PVC #

StorageClasses #

Persistent Volume Claims #

Persistent Volumes #

Horizontal Pod Autoscaler (HPA) #

Deploy HPA #

List & Watch HPA / Check Status #

List HPA Details #

Delete HPA #

ConfigMaps #

List ConfigMaps #

Edit ConfigMap #

List ConfigMap Details #

Delete ConfigMap #

Secrets #

List Secrets #