Docker
Command
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| docker run ubuntu sleep 5
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Dockerfile
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| FROM ubuntu:latest
# Correct
CMD sleep 5
CMD ["sleep", "5"]
# Incorrect
# CMD ["sleep 5"]
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Dockerfile and Command
CMD
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| FROM ubuntu:latest
CMD sleep 5
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| docker build -t ubunut-cmd-sleeper .
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| # sleep 5
docker run ubuntu-cmd-sleeper
# sleep 10
docker run ubuntu-cmd-sleeper sleep 10
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ENTRYPOINT
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| FROM ubuntu:latest
ENTRYPOINT ["sleep"]
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| docker build -t ubuntu-entrypoint-sleeper .
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| # Error
docker run ubuntu-entrypoint-sleeper
# sleep: missing operand
# Try 'sleep --help' for more information.
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| # sleep 20
docker run ubunut-entrypoint-sleeper 20
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ENTRYPOINT with Default Argument
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| FROM ubuntu:latest
ENTRYPOINT ["sleep"]
CMD ["3"]
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| docker build -t ubuntu-entrypoint-cmd-sleeper .
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| # sleep 3
docker run ubuntu-entrypoint-cmd-sleeper
# sleep 15
docker run ubuntu-entrypoint-cmd-sleeper 15
# cat /etc/passwd
docker run --entrypoint cat ubuntu-entrypoint-cmd-sleeper /etc/passwd
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Kubernetes
Base Docker Image
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| FROM ubuntu:latest
ENTRYPOINT ["sleep"]
CMD ["3"]
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| docker build -t ubuntu-sleeper .
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Docker Command to YAML
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| docker run --name sleeper-container ubuntu-sleeper
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ubuntu-sleeper.yaml
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| apiVersion: v1
kind: Pod
metadata:
name: ubuntu-sleeper-pod
spec:
restartPolicy: Never
containers:
- name: sleeper-container
image: ubunut-sleeper
imagePullPolicy: Never
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| kubectl create -f ubuntu-sleeper.yaml
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Docker Command to YAML with Argument Replacement
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2
| # sleep 3
docker run --name sleeper-container ubuntu-sleeper 50
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ubuntu-sleeper-argument.yaml
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| apiVersion: v1
kind: Pod
metadata:
name: ubuntu-sleeper-pod
spec:
restartPolicy: Never
containers:
- name: sleeper-container
image: ubunut-sleeper
imagePullPolicy: Never
args: [ "50" ]
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2
| # sleep 50
kubectl create -f ubuntu-sleeper-argument.yaml
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Docker Command to YAML with Command and Argument Replacement
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| docker run --name sleeper-container --entrypoint cat ubuntu-sleeper /etc/passwd
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ubuntu-sleeper-command-argument.yaml
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| apiVersion: v1
kind: Pod
metadata:
name: ubuntu-sleeper-pod
spec:
restartPolicy: Never
containers:
- name: sleeper-container
image: ubunut-sleeper
imagePullPolicy: Never
command: [ "cat" ]
args: [ "/etc/passwd" ]
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Or
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| apiVersion: v1
kind: Pod
metadata:
name: ubuntu-sleeper-pod
spec:
restartPolicy: Never
containers:
- name: sleeper-container
image: ubunut-sleeper
imagePullPolicy: Never
command:
- "cat"
- "/etc/passwd"
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Or
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| apiVersion: v1
kind: Pod
metadata:
name: ubuntu-sleeper-pod
spec:
restartPolicy: Never
containers:
- name: sleeper-container
image: ubunut-sleeper
imagePullPolicy: Never
command: [ "cat", "/etc/passwd" ]
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| # cat /etc/passwd
kubectl create -f ubuntu-sleeper-command-argument.yaml
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CozyFex