kubectl config get-contexts
Lists your cluster name, user, and namespace
kubectl cluster-info
Display addresses of the control plane and cluster services
kubectl version
Display the client and server k8s version
kubectl get nodes
List all nodes created in the cluster
kubectl help
Displays commands that help manage your cluster
kubectl config get-contexts
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl config get-contexts
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
* do-sgp1-k8s-1-28-2-do-0-sgp1-1704909404961 do-sgp1-k8s-1-28-2-do-0-sgp1-1704909404961 do-sgp1-k8s-1-28-2-do-0-sgp1-1704909404961-admin
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$
kubectl get nodes
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
aungkohtet-x1hk2 Ready <none> 12m v1.28.2
aungkohtet-x1hkl Ready <none> 12m v1.28.2
aungkohtet-x1hkp Ready <none> 12m v1.28.2
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get nodes -o wide
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
aungkohtet-x1hk2 Ready <none> 13m v1.28.2 10.104.0.4 157.245.207.215 Debian GNU/Linux 12 (bookworm) 6.1.0-12-amd64 containerd://1.6.22
aungkohtet-x1hkl Ready <none> 14m v1.28.2 10.104.0.3 157.245.202.10 Debian GNU/Linux 12 (bookworm) 6.1.0-12-amd64 containerd://1.6.22
aungkohtet-x1hkp Ready <none> 13m v1.28.2 10.104.0.2 157.245.200.251 Debian GNU/Linux 12 (bookworm) 6.1.0-12-amd64 containerd://1.6.22
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$
kubectl api-resources
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl api-resources
NAME SHORTNAMES APIVERSION NAMESPACED KIND
bindings v1 true Binding
componentstatuses cs v1 false ComponentStatus
configmaps cm v1 true ConfigMap
endpoints ep v1 true Endpoints
events ev v1 true Event
limitranges limits v1 true LimitRange
namespaces ns v1 false Namespace
nodes no v1 false Node
persistentvolumeclaims pvc v1 true PersistentVolumeClaim
persistentvolumes pv v1 false PersistentVolume
pods po v1 true Pod
podtemplates v1 true PodTemplate
replicationcontrollers rc v1 true ReplicationController
resourcequotas quota v1 true ResourceQuota
secrets v1 true Secret
serviceaccounts sa v1 true ServiceAccount
services svc v1 true Service
mutatingwebhookconfigurations admissionregistration.k8s.io/v1 false MutatingWebhookConfiguration
validatingwebhookconfigurations admissionregistration.k8s.io/v1 false ValidatingWebhookConfiguration
customresourcedefinitions crd,crds apiextensions.k8s.io/v1 false CustomResourceDefinition
apiservices apiregistration.k8s.io/v1 false APIService
controllerrevisions apps/v1 true ControllerRevision
daemonsets ds apps/v1 true DaemonSet
deployments deploy apps/v1 true Deployment
replicasets rs apps/v1 true ReplicaSet
statefulsets sts apps/v1 true StatefulSet
selfsubjectreviews authentication.k8s.io/v1 false SelfSubjectReview
tokenreviews authentication.k8s.io/v1 false TokenReview
localsubjectaccessreviews authorization.k8s.io/v1 true LocalSubjectAccessReview
selfsubjectaccessreviews authorization.k8s.io/v1 false SelfSubjectAccessReview
selfsubjectrulesreviews authorization.k8s.io/v1 false SelfSubjectRulesReview
subjectaccessreviews authorization.k8s.io/v1 false SubjectAccessReview
horizontalpodautoscalers hpa autoscaling/v2 true HorizontalPodAutoscaler
cronjobs cj batch/v1 true CronJob
jobs batch/v1 true Job
certificatesigningrequests csr certificates.k8s.io/v1 false CertificateSigningRequest
ciliumcidrgroups ccg cilium.io/v2alpha1 false CiliumCIDRGroup
ciliumclusterwidenetworkpolicies ccnp cilium.io/v2 false CiliumClusterwideNetworkPolicy
ciliumendpoints cep,ciliumep cilium.io/v2 true CiliumEndpoint
ciliumexternalworkloads cew cilium.io/v2 false CiliumExternalWorkload
ciliumidentities ciliumid cilium.io/v2 false CiliumIdentity
ciliuml2announcementpolicies l2announcement cilium.io/v2alpha1 false CiliumL2AnnouncementPolicy
ciliumloadbalancerippools ippools,ippool,lbippool,lbippools cilium.io/v2alpha1 false CiliumLoadBalancerIPPool
ciliumnetworkpolicies cnp,ciliumnp cilium.io/v2 true CiliumNetworkPolicy
ciliumnodeconfigs cilium.io/v2alpha1 true CiliumNodeConfig
ciliumnodes cn,ciliumn cilium.io/v2 false CiliumNode
ciliumpodippools cpip cilium.io/v2alpha1 false CiliumPodIPPool
leases coordination.k8s.io/v1 true Lease
databaseclusterreferences databases.digitalocean.com/v1alpha1 true DatabaseClusterReference
databaseclusters databases.digitalocean.com/v1alpha1 true DatabaseCluster
databaseuserreferences databases.digitalocean.com/v1alpha1 true DatabaseUserReference
databaseusers databases.digitalocean.com/v1alpha1 true DatabaseUser
endpointslices discovery.k8s.io/v1 true EndpointSlice
events ev events.k8s.io/v1 true Event
flowschemas flowcontrol.apiserver.k8s.io/v1beta3 false FlowSchema
prioritylevelconfigurations flowcontrol.apiserver.k8s.io/v1beta3 false PriorityLevelConfiguration
ingressclasses networking.k8s.io/v1 false IngressClass
ingresses ing networking.k8s.io/v1 true Ingress
networkpolicies netpol networking.k8s.io/v1 true NetworkPolicy
runtimeclasses node.k8s.io/v1 false RuntimeClass
poddisruptionbudgets pdb policy/v1 true PodDisruptionBudget
clusterrolebindings rbac.authorization.k8s.io/v1 false ClusterRoleBinding
clusterroles rbac.authorization.k8s.io/v1 false ClusterRole
rolebindings rbac.authorization.k8s.io/v1 true RoleBinding
roles rbac.authorization.k8s.io/v1 true Role
priorityclasses pc scheduling.k8s.io/v1 false PriorityClass
volumesnapshotclasses vsclass,vsclasses snapshot.storage.k8s.io/v1 false VolumeSnapshotClass
volumesnapshotcontents vsc,vscs snapshot.storage.k8s.io/v1 false VolumeSnapshotContent
volumesnapshots vs snapshot.storage.k8s.io/v1 true VolumeSnapshot
csidrivers storage.k8s.io/v1 false CSIDriver
csinodes storage.k8s.io/v1 false CSINode
csistoragecapacities storage.k8s.io/v1 true CSIStorageCapacity
storageclasses sc storage.k8s.io/v1 false StorageClass
volumeattachments storage.k8s.io/v1 false VolumeAttachment
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get namespaces -o wide
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get namespaces -o wide
NAME STATUS AGE
default Active 23m
kube-node-lease Active 23m
kube-public Active 23m
kube-system Active 23m
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ - kubectl get —-help
- kubectl get namespace -o yaml
- kubectl get all -n kube-system
check the api resources which reside in the kube-system (important). Must understand these components.
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get namespace -o yaml
apiVersion: v1
items:
- apiVersion: v1
kind: Namespace
metadata:
creationTimestamp: "2024-01-10T17:58:37Z"
labels:
kubernetes.io/metadata.name: default
name: default
resourceVersion: "36"
uid: 6388977d-3062-4635-8096-53d002ec781e
spec:
finalizers:
- kubernetes
status:
phase: Active
- apiVersion: v1
kind: Namespace
metadata:
creationTimestamp: "2024-01-10T17:58:37Z"
labels:
kubernetes.io/metadata.name: kube-node-lease
name: kube-node-lease
resourceVersion: "34"
uid: f4f421c4-4eb0-4531-9c6b-a86af2026726
spec:
finalizers:
- kubernetes
status:
phase: Active
- apiVersion: v1
kind: Namespace
metadata:
creationTimestamp: "2024-01-10T17:58:37Z"
labels:
kubernetes.io/metadata.name: kube-public
name: kube-public
resourceVersion: "24"
uid: aafb519d-0511-4402-abc6-46ae23daf95c
spec:
finalizers:
- kubernetes
status:
phase: Active
- apiVersion: v1
kind: Namespace
metadata:
creationTimestamp: "2024-01-10T17:58:37Z"
labels:
kubernetes.io/metadata.name: kube-system
name: kube-system
resourceVersion: "11"
uid: 414d1eba-789a-4068-803b-0db18f30cbf5
spec:
finalizers:
- kubernetes
status:
phase: Active
kind: List
metadata:
resourceVersion: ""
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get all -n kube-system
NAME READY STATUS RESTARTS AGE
pod/cilium-jtjj8 1/1 Running 0 21m
pod/cilium-operator-66ccb9ddb7-tw77f 1/1 Running 0 25m
pod/cilium-v9hv7 1/1 Running 0 21m
pod/cilium-vwpfv 1/1 Running 0 21m
pod/coredns-7dbbf6dd5b-7frbc 1/1 Running 0 19m
pod/coredns-7dbbf6dd5b-cpt6l 1/1 Running 0 19m
pod/cpc-bridge-proxy-trvpd 1/1 Running 0 20m
pod/cpc-bridge-proxy-v5cjs 1/1 Running 0 20m
pod/cpc-bridge-proxy-w7t9l 1/1 Running 0 20m
pod/csi-do-node-dlqw2 2/2 Running 0 19m
pod/csi-do-node-m9ddc 2/2 Running 0 19m
pod/csi-do-node-mdktf 2/2 Running 0 19m
pod/disable-systemd-upgrade-timer-9vgzz 1/1 Running 0 20m
pod/disable-systemd-upgrade-timer-m77h7 1/1 Running 0 20m
pod/disable-systemd-upgrade-timer-rq4vn 1/1 Running 0 20m
pod/do-node-agent-2pz6c 1/1 Running 0 19m
pod/do-node-agent-49ff9 1/1 Running 0 19m
pod/do-node-agent-sqnh5 1/1 Running 0 19m
pod/konnectivity-agent-9p9v9 1/1 Running 0 21m
pod/konnectivity-agent-lcsvt 1/1 Running 0 21m
pod/konnectivity-agent-vmx7q 1/1 Running 0 21m
pod/kube-proxy-vmvm2 1/1 Running 0 21m
pod/kube-proxy-xl98t 1/1 Running 0 21m
pod/kube-proxy-xpngv 1/1 Running 0 21m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kube-dns ClusterIP 10.245.0.10 <none> 53/UDP,53/TCP,9153/TCP 19m
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE
daemonset.apps/cilium 3 3 3 3 3 kubernetes.io/os=linux 25m
daemonset.apps/cpc-bridge-proxy 3 3 3 3 3 <none> 20m
daemonset.apps/csi-do-node 3 3 3 3 3 <none> 19m
daemonset.apps/disable-systemd-upgrade-timer 3 3 3 3 3 <none> 20m
daemonset.apps/do-node-agent 3 3 3 3 3 kubernetes.io/os=linux 19m
daemonset.apps/konnectivity-agent 3 3 3 3 3 <none> 21m
daemonset.apps/kube-proxy 3 3 3 3 3 <none> 25m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/cilium-operator 1/1 1 1 25m
deployment.apps/coredns 2/2 2 2 19m
NAME DESIRED CURRENT READY AGE
replicaset.apps/cilium-operator-66ccb9ddb7 1 1 1 25m
replicaset.apps/coredns-7dbbf6dd5b 2 2 2 19m
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get pod -n kube-system
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get pod -n kube-system
NAME READY STATUS RESTARTS AGE
cilium-jtjj8 1/1 Running 0 22m
cilium-operator-66ccb9ddb7-tw77f 1/1 Running 0 26m
cilium-v9hv7 1/1 Running 0 22m
cilium-vwpfv 1/1 Running 0 22m
coredns-7dbbf6dd5b-7frbc 1/1 Running 0 21m
coredns-7dbbf6dd5b-cpt6l 1/1 Running 0 21m
cpc-bridge-proxy-trvpd 1/1 Running 0 21m
cpc-bridge-proxy-v5cjs 1/1 Running 0 21m
cpc-bridge-proxy-w7t9l 1/1 Running 0 21m
csi-do-node-dlqw2 2/2 Running 0 20m
csi-do-node-m9ddc 2/2 Running 0 20m
csi-do-node-mdktf 2/2 Running 0 20m
disable-systemd-upgrade-timer-9vgzz 1/1 Running 0 21m
disable-systemd-upgrade-timer-m77h7 1/1 Running 0 21m
disable-systemd-upgrade-timer-rq4vn 1/1 Running 0 21m
do-node-agent-2pz6c 1/1 Running 0 20m
do-node-agent-49ff9 1/1 Running 0 20m
do-node-agent-sqnh5 1/1 Running 0 20m
konnectivity-agent-9p9v9 1/1 Running 0 22m
konnectivity-agent-lcsvt 1/1 Running 0 22m
konnectivity-agent-vmx7q 1/1 Running 0 22m
kube-proxy-vmvm2 1/1 Running 0 22m
kube-proxy-xl98t 1/1 Running 0 22m
kube-proxy-xpngv 1/1 Running 0 22m
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get service -n kube-system -o wide
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get service -n kube-system -o wide
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
kube-dns ClusterIP 10.245.0.10 <none> 53/UDP,53/TCP,9153/TCP 22m k8s-app=kube-dns
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl config get-contexts
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl config get-contexts
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
* do-sgp1-k8s-1-28-2-do-0-sgp1-1704909404961 do-sgp1-k8s-1-28-2-do-0-sgp1-1704909404961 do-sgp1-k8s-1-28-2-do-0-sgp1-1704909404961-admin
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$
kubectl get nodes --context do-sgp1-k8s-1-28-2-do-0-sgp1-1704909404961
create nginx deployment
kubectl create deployment nginx --image=nginx:latest --port=80- Verify
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl create deployment nginx --image=nginx:latest --port=80
deployment.apps/nginx created
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get all
NAME READY STATUS RESTARTS AGE
pod/nginx-7c79c4bf97-2584q 1/1 Running 0 14s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.245.0.1 <none> 443/TCP 36m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nginx 1/1 1 1 14s
NAME DESIRED CURRENT READY AGE
replicaset.apps/nginx-7c79c4bf97 1 1 1 14s
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ scale up the deployment with 3 replicas
kubectl scale deployment nginx --replicas=3- Verify
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl scale deployment nginx --replicas=3
deployment.apps/nginx scaled
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get all
NAME READY STATUS RESTARTS AGE
pod/nginx-7c79c4bf97-2584q 1/1 Running 0 2m38s
pod/nginx-7c79c4bf97-cztn5 1/1 Running 0 29s
pod/nginx-7c79c4bf97-ktxmg 1/1 Running 0 29s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.245.0.1 <none> 443/TCP 39m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nginx 3/3 3 3 2m38s
NAME DESIRED CURRENT READY AGE
replicaset.apps/nginx-7c79c4bf97 3 3 3 2m38s
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ create service(svc) to access from external
kubectl expose deployment nginx --name=nginx-svc --port 80 --type=ClusterIP- Verify
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl expose deployment nginx --name=nginx-svc --port 80 --type=ClusterIP
service/nginx-svc exposed
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.245.0.1 <none> 443/TCP 43m
nginx-svc ClusterIP 10.245.151.235 <none> 80/TCP 19s
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ -
Let’s explore with dnstools and deploy it
-
kubectl apply -f dnstools.yaml -
enter to that dnstools pod and explore with curl to the create nginx-svc
-
kubectl exec -it dnstools -- sh -
Verify
Aungs-MacBook-Pro:basic-command-part-1 aungkohtet$ kubectl apply -f dnstools.yaml
pod/dnstools created
Aungs-MacBook-Pro:basic-command-part-1 aungkohtet$ kubectl exec -it dnstools -- sh
dnstools# curl nginx-svc
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>- change the nginx-svc type from ClusterIP to NodePort
kubectl edit svc nginx-svc # change type = NodePort
#
apiVersion: v1
kind: Service
metadata:
creationTimestamp: "2024-01-10T18:42:12Z"
labels:
app: nginx
name: nginx-svc
namespace: default
resourceVersion: "10131"
uid: 97ab9ad8-38ce-4f9b-a5bd-807c54f32b9e
spec:
clusterIP: 10.245.151.235
clusterIPs:
- 10.245.151.235
internalTrafficPolicy: Cluster
ipFamilies:
- IPv4
ipFamilyPolicy: SingleStack
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
app: nginx
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}-
port-forwarding shall be done in order to access the port IP from outside
-
kubectl port-forward service/nginx-svc --address 0.0.0.0 8080:80 -
Verify
In this case, we’re testing with virtualbox and try to access the virtual machine ip address with respective port number
Aungs-MacBook-Pro:basic-command-part-1 aungkohtet$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.245.0.1 <none> 443/TCP 61m
nginx-svc NodePort 10.245.151.235 <none> 80:30524/TCP 17m
Aungs-MacBook-Pro:basic-command-part-1 aungkohtet$ curl 10.245.151.235:30524
^C
Aungs-MacBook-Pro:basic-command-part-1 aungkohtet$ kubectl port-forward service/nginx-svc --address 0.0.0.0 8080:30524
error: Service nginx-svc does not have a service port 30524
Aungs-MacBook-Pro:basic-command-part-1 aungkohtet$ kubectl port-forward service/nginx-svc --address 0.0.0.0 8080:80
Forwarding from 0.0.0.0:8080 -> 80
^CAungs-MacBook-Pro:basic-command-part-1 aungkohtet$ kubectl port-forward service/nginx-svc --address 0.0.0.0 8080:80
Forwarding from 0.0.0.0:8080 -> 80
Handling connection for 8080
Handling connection for 8080
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$ curl 192.168.100.220:8080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
Aungs-MacBook-Pro:Kubernetes-in-Action aungkohtet$