¶ Create a Pod with two containers, both with image busybox and command "echo hello; sleep 3600". Connect to the second container and run 'ls'
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Easiest way to do it is create a pod with a single container and save its definition in a YAML file:
kubectl run busybox --image=busybox --restart=Never -o yaml --dry-run=client -- /bin/sh -c 'echo hello;sleep 3600' > pod.yaml
vi pod.yaml
Copy/paste the container related values, so your final YAML should contain the following two containers (make sure those containers have a different name):
containers:
- args:
- /bin/sh
- -c
- echo hello;sleep 3600
image: busybox
imagePullPolicy: IfNotPresent
name: busybox
resources: {}
- args:
- /bin/sh
- -c
- echo hello;sleep 3600
image: busybox
name: busybox2
kubectl create -f pod.yaml
# Connect to the busybox2 container within the pod
kubectl exec -it busybox -c busybox2 -- /bin/sh
ls
exit
# or you can do the above with just an one-liner
kubectl exec -it busybox -c busybox2 -- ls
# you can do some cleanup
kubectl delete po busybox
¶ Create pod with nginx container exposed at port 80. Add a busybox init container which downloads a page using "wget -O /work-dir/index.html http://neverssl.com/online". Make a volume of type emptyDir and mount it in both containers. For the nginx container, mount it on "/usr/share/nginx/html" and for the initcontainer, mount it on "/work-dir". When done, get the IP of the created pod and create a busybox pod and run "wget -O- IP"
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Easiest way to do it is create a pod with a single container and save its definition in a YAML file:
kubectl run web --image=nginx --restart=Never --port=80 --dry-run=client -o yaml > pod-init.yaml
Copy/paste the container related values, so your final YAML should contain the volume and the initContainer:
Volume:
containers:
- image: nginx
...
volumeMounts:
- name: vol
mountPath: /usr/share/nginx/html
volumes:
- name: vol
emptyDir: {}
initContainer:
...
initContainers:
- args:
- /bin/sh
- -c
- wget -O /work-dir/index.html http://neverssl.com/online
image: busybox
name: box
volumeMounts:
- name: vol
mountPath: /work-dir
In total you get:
apiVersion: v1
kind: Pod
metadata:
labels:
run: box
name: box
spec:
initContainers: #
- args: #
- /bin/sh #
- -c #
- wget -O /work-dir/index.html http://neverssl.com/online #
image: busybox #
name: box #
volumeMounts: #
- name: vol #
mountPath: /work-dir #
containers:
- image: nginx
name: nginx
ports:
- containerPort: 80
volumeMounts: #
- name: vol #
mountPath: /usr/share/nginx/html #
volumes: #
- name: vol #
emptyDir: {} #
# Apply pod
kubectl apply -f pod-init.yaml
# Get IP
kubectl get po -o wide
# Execute wget
kubectl run box --image=busybox --restart=Never -it --rm -- /bin/sh -c "wget -O- IP"
# you can do some cleanup
kubectl delete po box
¶ Create a Pod with three busy box containers with commands “ls; sleep 3600;”, “echo Hello World; sleep 3600;” and “echo this is the third container; sleep 3600” respectively and check the status
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// first create single container pod with dry run flag
kubectl run busybox --image=busybox --restart=Never --dry-run -o yaml -- bin/sh -c "sleep 3600; ls" > multi-container.yaml
// edit the pod to following yaml and create it
kubectl create -f multi-container.yaml
kubectl get po busybox
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: busybox
name: busybox
spec:
containers:
- args:
- bin/sh
- -c
- ls; sleep 3600
image: busybox
name: busybox1
resources: {}
- args:
- bin/sh
- -c
- echo Hello world; sleep 3600
image: busybox
name: busybox2
resources: {}
- args:
- bin/sh
- -c
- echo this is third container; sleep 3600
image: busybox
name: busybox3
resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Never
status: {}
¶ Create a Pod with main container busybox and which executes this “while true; do echo ‘Hi I am from Main container’ >> /var/log/index.html; sleep 5; done” and with sidecar container with nginx image which exposes on port 80. Use emptyDir Volume and mount this volume on path /var/log for busybox and on path /usr/share/nginx/html for nginx container. Verify both containers are running.
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// create an initial yaml file with this
kubectl run multi-cont-pod --image=busbox --restart=Never --dry-run -o yaml > multi-container.yaml
// edit the yml as below and create it
kubectl create -f multi-container.yaml
kubectl get po multi-cont-pod
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: multi-cont-pod
name: multi-cont-pod
spec:
volumes:
- name: var-logs
emptyDir: {}
containers:
- image: busybox
command: ["/bin/sh"]
args: ["-c", "while true; do echo 'Hi I am from Main container' >> /var/log/index.html; sleep 5;done"]
name: main-container
resources: {}
volumeMounts:
- name: var-logs
mountPath: /var/log
- image: nginx
name: sidecar-container
resources: {}
ports:
- containerPort: 80
volumeMounts:
- name: var-logs
mountPath: /usr/share/nginx/html
dnsPolicy: ClusterFirst
restartPolicy: Never
status: {}
¶ Exec into both containers and verify that main.txt exist and query the main.txt from sidecar container with curl localhost
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// exec into main container
kubectl exec -it multi-cont-pod -c main-container -- sh
cat /var/log/main.txt
// exec into sidecar container
kubectl exec -it multi-cont-pod -c sidecar-container -- sh
cat /usr/share/nginx/html/index.html
// install curl and get default page
kubectl exec -it multi-cont-pod -c sidecar-container -- sh
# apt-get update && apt-get install -y curl
# curl localhost
¶ Get the pods with labels env=dev and env=prod
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kubectl get pods -l 'env in (dev,prod)'
¶ Get the pods with labels env=dev and env=prod and output the labels as well
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kubectl get pods -l 'env in (dev,prod)' --show-labels
¶ Change the label for one of the pod to env=uat and list all the pods to verify
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kubectl label pod/nginx-dev3 env=uat --overwrite
kubectl get pods --show-labels