Config

CLI Setup

alias k=kubectl
Create alias for kubectl.

source <(kubectl completion bash)
Enable kubectl completion.

Kubeconfig

kubectl cluster-info --kubeconfig /path/to/kubeconfig.yml
Show info about the specifed Kubeconfig file.

export KUBECONFIG=/path/to/kubeconfig.yml
Set the Kubeconfig file to use.
kubectl config view
Show configured clusters in the current Kubeconfig file.

Context

kubectl -context my-context-name get pods
Specify context in a command.
kubectl -n my-namespace get pods
Specify namespace in a command.

kubectl config use-context myContext
Switch to the specify context.

kubectl config current-context
Show current context.
kubectl config view --minify | grep namespace:
Show current namespace (other method).

kubectl config set-context --current --namespace myNameSpace
Set namespace for current context.
kubectl config unset current-context
Unset current context.

AWS EKS Kubeconfig

aws eks update-kubeconfig --name my-cluster
Update ~/.kube/config file to be able to connect to the cluster.

Basis

Apply

kubectl apply -f myResoyrce.yml
Create or update a resource from a YAML file.
kubectl apply -f /myResourcesFolder
Create or update multiple resources from YAML files in a folder (requires --- at the beginning of files).

Get

kubectl get nodes
List nodes.
kubectl get services
Return active services.
kubectl get ingress
Show ingress.
kubectl get deployments
Show deployments.
kubectl get pods
Show Pods.

Describe

kubectl describes nodes myNode
Return information about the resource.

Delete

kubectl delete pod my-pod
Delete Pod.
kubectl delete pod my-pod --now
Delete Pod now.
kubectl delete pod my-pod --force
Force delete the Pod.
kubectl delete pods --all
Delete all Pods.

kubectl delete -f myDeployment.yml
Delete deployment from file.

Ouput

kubectl get pods -o wide
Ouput more info (e.g. for Pods, outputs Node and IP).

kubectl get deployment -o custom-columns=DEPLOYMENT:.metadata.name,CONTAINER_IMAGE:.spec.template.spec.containers[].image,READY_REPLICAS:.status.readyReplicas --sort-by=.metadata.name
Custom column output.

kubectl get pods my-pod -o yaml
Ouput yaml configuration.

kubectl get nodes -o jsonpath='{.items[*].status.nodeInfo.osImage}'
Jsonpath output.

Flags

--no-headers
Do not output headers.

--as myUser
Execute command as another user.

Monitoring

Metrics Server

Note: For the Metrics API to be available, metrics-server has to be installed on the cluster.

kubectl top nodes
Show nodes metrics.
kubectl top pods
Show pods metrics.

Metadata

Labels

kubectl label node myNode myLabel=myValue
Add a Label to a Node.
kubectl label node myNode myLabel-
Remove a Label from a Node.

Label Selector

kubectl get pod --selector myLablel=myValue
Get pods based on label value.

kubectl get pod --selector myLablel=myValue,myLablel2=myValue2
Get pods based on multiple labels values.

Nodes

Unschedule

kubectl cordon myNode
Mark the node as unschedulable (node status will be Ready,SchedulingDisabled).
kubectl uncordon myNode
Mark the node as schedulable (node status will be Ready).

kubectl drain myNode
Mark the node as unschedulable and empty it from its pods.
kubectl drain myNode --ignore-daemonsets
Allows to drain node even if there are DaemonSets (DaemonSets can create Pods that ignore unschedulable taints).
kubectl drain myNode --force
Allows to drain node even if there are Pods that are not declared in the controller (Pods not in Job, DaemonSet, ReplicationSet, ...). Warning: pods that are not in the controller will be lost.

Taint

kubectl taint node myNode myKey=myValue:myEffect
Add a Taint to a Node (effect can be NoExecute, NoSchedule, PreferNoSchedule...)

kubectl taint node myNode myKey=myValue:myEffect-
Remove Taint from a Node.

Pods

Static Pods

To create a static pod, look at the path configured for staticPodPath in /var/lib/kubelet/config.yaml. Then create a manifest and move it in the specified path.

kubectl describe pods -A | grep "Controlled By"
Find Static Pods (they are the ones controlled by Node/controlplane).

Run (imperative)

kubectl run webserver --image=httpd
Start a Pod (Appache in this case).
kubectl run webserver --image=httpd --port=80
Start a Pod and set the containerPort spec.
Like EXPOSE it is for information purpose only: it does not actually publish the port.

kubectl run my-pod --image=myImage -- /bin/bash
Run a Pod that overrides the CMD of the container.
kubectl run my-pod --image=myImage --command -- /bin/bash --myArg
Run a Pod that overrides the ENTRYPOINT and the CMD of the container.
kubectl run my-pod --image=myImage -rm -it --command -- /bin/bash --myArg
Run a Pod that is interactive (-it) and gets deleted when exited (--rm)

Exec

kubectl exec my-pod -c my-container -it -- /bin/bash
Exec a command in a container (when there is only one container -c is not required).

Logs

kubectl logs my-pod -c my-container
Show logs of the specified container (when there is only one container -c is not required).

kubectl logs -f my-pod
Show and follows logs.

Edit

kubectl edit pod myPod
Edit pod configuration

The only specifications that can be edited without --force are the following:

spec.containers[*].image
spec.initContainers[*].image
spec.activeDeadlineSeconds
spec.tolerations

Deployments

Create

kubectl create my-deployment --image=httpd:alpine --replicas=4
Create a deployment with 4 replicas.

Update (imperative)

kubectl scale deployment my-deployment --replicas 4
Change the number of replicas for the Deployment.

kubectl set image deployment/my-deployment my-container=my-new-image
Change the image used in a Deployment.

kubectl rollout status deployment/my-deployment
Show rollout status.

Service Exposure

Port Forward (imperative)

kubectl port-forward my-pod <HOST_PORT>:<POD_PORT>
Create a port forward to the specified pod.
Access via localhost:<POD_PORT>

Expose Services (imperative)

kubectl expose pod my-pod --type=ClusterIP --port=<POD_PORT> --name my-app-service
Create a service of type ClusterIP.
Access via <CLUSTER_IP>:<POD_PORT> (only accessible inside the cluster).
kubectl expose pod my-pod --type=NodePort --port=<POD_PORT> --name my-app-service
Create a service of type NodePort.
Access via <ANY_NODE_IP>:<NODE_PORT>
kubectl expose pod my-pod --type=LoadBalancer --port=<POD_PORT> --name my-app-service
Create a service of type LoadBalancer (requires that cluster is able to ask for a load balancer).
Access via <EXTERNAL_IP>:<POD_PORT> (EXTERNAL_IP is the IP of the Load Balancer).

Ingress

kubectl create ingress my-ingress --rule="/mypath=my-app-cluster-ip-service:8080"
Create an Ingress that route traffic address to /mypath path.

kubectl create ingress my-ingress --rule="myapp.local/*=my-app-cluster-ip-service:8080"
Create an Ingress that route traffic addressed to myapp.local host.

Here are some annotations that could be usefull when using an Ingress of type Nginx.

metadata:
  annotations:
    # Allow to do /myapp -> /
    nginx.ingress.kubernetes.io/rewrite-target: /
    # Redirect HTTP traffic to HTTPS
    nginx.ingress.kubernetes.io/ssl-redirect: "true"

Secrets

Create

kubectl create secret generic mySecret --from-literal my_key_1=my_value_1 --from-literal my_key_2=my_value_2
Create a generic Secret.

kubectl create secret docker-registry my-private-reg-creds --docker-server=myprivateregistry.com:5000 --docker-username=dock_user --docker-password=dock_password --docker-email=dock_user@myprivateregistry.com
Create a docker-registry Secret.

Example of the usage of a docker-registry Secret:

deployment
  spec:
      imagePullSecrets:
      - name: private-reg-cred
      containers:
      - image: myprivateregistry.com:5000/nginx:alpine
        imagePullPolicy: IfNotPresent

Certificates

Signing Requests

kubect get certificatesigningrequests.certificates.k8s.io
Return Signing Requests.

cat my-signing-request.csr | base64 -w 0
Ouput base64 as only one line

apiVersion: certificates.k8s.io/v1
kind: CertificateSigningRequest
metadata:
  name: my-singing-request
spec:
  request: LS0tLS1CRUdJTiBDRV...
  signerName: kubernetes.io/kube-apiserver-client
  usages:
    - client auth

Create a Singing Request.

kubectl certificate approve my-singing-request
Approve Singning Request.

OpenSSL

openssl x509 -in /etc/kubernetes/pki/apiserver.crt -text -noout
Output certificate content.

RBAC

Service Accounts

kubectl create serviceaccount my-service-account
Create a Serivce Account.

# Specify Service Account for a resource
spec:
    spec:
      serviceAccountName: dashboard-sa

kubectl create token my-service-account
Create a Service Account token (JWT).

Roles

kubectl create role developer --verb=list,create,delete --resource=pods
Create a Role (can list, create, delete Pods).

kubectl create rolebinding dev-user-binding --role=developer --serviceaccount=default:dev-user
Create a Binding between a Role and a Service Account.

Cluster Roles

kubectl create clusterrole storage-admin --verb=* --resource=storageclasses --resource=persistentvolumes
Create a Cluster Role (can do anything on Persistant Volumes).

kubectl create clusterrolebinding myUser-storage-admin --clusterrole=storage-admin --user=myUser
Create a Binding between a Role and a User.

Troubleshooting

Broken Scheduler

If the scheduler isn't working, check the configuration of /etc/kubernetes/manifests/kube-scheduler.yaml.

Broken Worker Node

If a Worker Node isn't working, try systemctl status kubelet.service

If the service don't start check:
- journalctl -u kubelet.service
- /var/lib/kubelet/config.yaml
If Connection refused to control node check the Kubeconfig file:
- Is the port right? server: https://controlplane:6443

Troubleshoot Containers

crictl ps -a
See Containers that are CRI-compatible.

crictl logs containerID
See Logs for a container.

Misc

Get all Objects

kubectl get all
Get info about all objects.

Get all Images

kubectl get pods --all-namespaces -o jsonpath="{.items[].spec.containers[].image}" | \ tr -s '[[:space:]]' '\n' | \
sort | \ uniq -c
Retrieve all images used by pods in the cluster.

Find Resouces API Name

kubectl api-resources | grep storage
Find the API name of a resource using keyword.

Get Cluster IP Ranges Config

kubectl logs -n kube-system weave-net | grep ipalloc-range
Find Pods IP range configuration.
cat /etc/kubernetes/manifests/kube-apiserver.yaml | grep "--service-cluster-ip-range="
Find Services IP range configuration.

Expose Kube-apiserver

kubectl proxy
Expose Kube-apiserver to localhost.

Config#

CLI Setup#

Kubeconfig#

Context#

AWS EKS Kubeconfig#

Basis#

Apply#

Get#

Describe#

Delete#

Ouput#

Flags#

Monitoring#

Metrics Server#

Metadata#

Labels#

Label Selector#

Nodes#

Unschedule#

Taint#

Pods#

Static Pods#

Run (imperative)#

Exec#

Logs#

Edit#

Deployments#

Create#

Update (imperative)#

Service Exposure#

Port Forward (imperative)#

Expose Services (imperative)#

Ingress#

Secrets#

Create#

Certificates#

Signing Requests#

OpenSSL#

RBAC#

Service Accounts#

Roles#

Cluster Roles#

Troubleshooting#

Broken Scheduler#

Broken Worker Node#

Troubleshoot Containers#

Misc#

Get all Objects#

Get all Images#

Find Resouces API Name#

Get Cluster IP Ranges Config#

Expose Kube-apiserver#

Config

CLI Setup

Kubeconfig

Context

AWS EKS Kubeconfig

Basis

Apply

Get

Describe

Delete

Ouput

Flags

Monitoring

Metrics Server

Metadata

Labels

Label Selector

Nodes

Unschedule

Taint

Pods

Static Pods

Run (imperative)

Exec

Logs

Edit

Deployments

Create

Update (imperative)

Service Exposure

Port Forward (imperative)

Expose Services (imperative)

Ingress

Secrets

Create

Certificates

Signing Requests

OpenSSL

RBAC

Service Accounts

Roles

Cluster Roles

Troubleshooting

Broken Scheduler

Broken Worker Node

Troubleshoot Containers

Misc

Get all Objects

Get all Images

Find Resouces API Name

Get Cluster IP Ranges Config

Expose Kube-apiserver