Introduction
Hi, I am Akshay Rao. i am starting a Kubernetes hands-on series. This will help you to pass the CKAD exam.
Note:- Kubernetes will be addressed as K8s, bcoz i am lazy to type.
Pre-requisite
- Need to be familiar with k8s jargon like pod, namespace and also need basic understanding of containers.
- Need to install Minikube and kubectl in the local machine. https://minikube.sigs.k8s.io/docs/start/ https://kubernetes.io/docs/tasks/tools/
Agenda
In this we will create a simple pod in a custom created namespace(hands-on), understand different parts and see the other kubectl commands related to pod.
Let's start
- We are brought to the default namespace, there is no namespace named "hands-on".
[k8s-ckad (⎈|minikube:default)]$ kubectl get namespaces
NAME STATUS AGE
default Active 29m
kube-node-lease Active 29m
kube-public Active 29m
kube-system Active 29m
- need to create a namespace name "hands-on"
[k8s-ckad (⎈|minikube:default)]$ kubectl create namespace hands-on
namespace/hands-on created
- now need to switch to this namespace
[k8s-ckad (⎈|minikube:default)]$ kubectl config set-context --current --namespace=hands-on
Context "minikube" modified.
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
* minikube minikube minikube hands-on
- now to create a pod create a file
vi pod1.yamland write the following snippet.
apiVersion: v1 # version of K8s Api using
kind: pod # what we are trying to create
metadata:
name: pod1 # pod name
spec:
containers:
- name: nginx # container name
image: nginx:latest # container image
ports:
- containerPort: 80 #configure the pod to expose port 80
- Create a pod and verify
[k8s-ckad (⎈|minikube:default)]$ kubectl create -f pod1.yaml
pod/pod1 created
[k8s-ckad (⎈|minikube:hands-on)]$ k get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod1 1/1 Running 0 15s 172.17.0.3 minikube <none> <none>
- now lets see other kubectl commands
[k8s-ckad (⎈|minikube:default)]$ kubectl describe pods pod1
Name: pod1
Namespace: hands-on
Priority: 0
Service Account: default
Node: minikube/192.168.49.2
Start Time: Mon, 02 Oct 2023 23:14:45 +0900
Labels: <none>
Annotations: <none>
Status: Running
IP: 172.17.0.3
IPs:
IP: 172.17.0.3
Containers:
nginx:
Container ID: docker://7c55270c7615a5e8ad533af9e82990bfcad855625b0440ab97b57fb5319e1d62
Image: nginx:latest
Image ID: docker-pullable://nginx@sha256:32da30332506740a2f7c34d5dc70467b7f14ec67d912703568daff790ab3f755
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Mon, 02 Oct 2023 23:15:02 +0900
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-vvqt8 (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-vvqt8:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 118s default-scheduler Successfully assigned default/pod1 to minikube
Normal Pulling 117s kubelet Pulling image "nginx:latest"
Normal Pulled 101s kubelet Successfully pulled image "nginx:latest" in 15.837068995s
Normal Created 101s kubelet Created container nginx
Normal Started 101s kubelet Started container nginx
describe command is used for troubleshooting, in the events section all the event will be given. In this all the information related to pod will be given.
Seeing Logs
[k8s-ckad (⎈|minikube:default)]$ kubectl logs pod1
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Sourcing /docker-entrypoint.d/15-local-resolvers.envsh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2023/10/02 14:15:02 [notice] 1#1: using the "epoll" event method
2023/10/02 14:15:02 [notice] 1#1: nginx/1.25.2
2023/10/02 14:15:02 [notice] 1#1: built by gcc 12.2.0 (Debian 12.2.0-14)
2023/10/02 14:15:02 [notice] 1#1: OS: Linux 5.15.49-linuxkit
2023/10/02 14:15:02 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2023/10/02 14:15:02 [notice] 1#1: start worker processes
2023/10/02 14:15:02 [notice] 1#1: start worker process 30
2023/10/02 14:15:02 [notice] 1#1: start worker process 31
2023/10/02 14:15:02 [notice] 1#1: start worker process 32
2023/10/02 14:15:02 [notice] 1#1: start worker process 33
now delete the pod
[k8s-ckad (⎈|minikube:default)]$ kubectl delete pod pod1
pod "pod1" deleted
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