kubernetes exr1 pod
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# How many pods exist on the system?
kubectl get pods
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# Create a new pod with the nginx image.
kubectl run nginx --image=nginx
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# What is the image used to create the new pods?
# You must look at one of the new pods in detail to figure this out.
kubectl describe pod <pod-name>
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# Which nodes are these pods placed on?
kubectl get pods -o wide
or
kubectl describe pod <pod-name>
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# How many containers are part of the pod webapp?
kubectl describe pod webapp
Name: webapp
Namespace: default
Priority: 0
Node: controlplane/172.25.0.77
Start Time: Sat, 16 Apr 2022 12:53:34 +0000
Labels: <none>
Annotations: <none>
Status: Pending
IP: 10.42.0.13
IPs:
IP: 10.42.0.13
Containers:
# here
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# What images are used in the new webapp pod?
# You must look at all the pods in detail to figure this out.
kubectl describe pod webapp
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# What is the state of the container agentx in the pod webapp?
# Wait for it to finish the ContainerCreating state
kubectl describe pod webapp
# waitting
agentx:
Container ID:
Image: agentx
Image ID:
Port: <none>
Host Port: <none>
State: Waiting
Reason: ErrImagePull
Ready: False
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# Why do you think the container agentx in pod webapp is in error?
Reason: ErrImagePull
# A Docker image with this name doesn't exist on Docker Hub
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# What does the READY column in the output of the kubectl get pods command indicate?
# Running Containers in POD/Total Containers in POD
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# Delete the webapp Pod.
# Once deleted, wait for the pod to fully terminate.
kubectl delete pod webapp
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# Create a new pod with the name redis and with the image redis123.
# Use a pod-definition YAML file. And yes the image name is wrong!
# redis => name,run=redis
# --dry-run=client => not run
kubectl run redis --image=redis123 --dry-run=client -o yaml > pod-definition.yaml
kubectl create -f pod-definition.yaml
kubectl get pods
# redis 0/1 ErrImagePull 0 8s
kubectl describe pod redis
#
Name: redis
Namespace: default
Priority: 0
Node: controlplane/172.25.0.77
Start Time: Sat, 16 Apr 2022 13:05:21 +0000
Labels: run=redis
Annotations: <none>
Status: Pending
IP: 10.42.0.14
IPs:
IP: 10.42.0.14
Containers:
redis:
Container ID:
Image: redis123
Image ID:
Port: <none>
Host Port: <none>
State: Waiting
Reason: ImagePullBackOff
Ready: False
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# Now change the image on this pod to redis.
# Once done, the pod should be in a running state.
kubectl edit pod redis
# change image redis123 => redis
or
vi pod-definition.yaml
# spec:
# containers:
# - image: redis <= change
kubectl apply -f pod-definition.yaml
# 변경된 파일 사항을 Pod에 적용
# create 를 대신하여 사용해도 pod는 생성된다.
| command | 기존 리소스 없음 | 기존 리소스가 존재 |
|---|---|---|
| create | 새로운 리소스가 생성 | ERROR가 발생 |
| apply | 새로운 리소스가 생성 | 부분적인 spec을 적용 |
| replace | ERROR가 발생 | 리소스가 삭제된 뒤 새롭게 생성 |