WEBVTT

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Hello and welcome to this lecture in this lecture.

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We will now look at Command and Arguments in a Kubernetes POD. In the previous lecture we created a simple

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Docker image that sleeps for a given number of seconds.

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We named it ubuntu-sleeper and we ran it using the docker command docker run ubuntu-sleeper. By default

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It sleeps for five seconds but you can override it by passing a command line argument.

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We will now create a pod using this image.

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We start with a blank pod definition template,

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input the name of the pod and specify the image name.

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When the pod is created, it creates a container from the specified image, and the container sleeps for

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five seconds before exiting.

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Now if you need the container to sleep for 10 seconds as in the second command how do you specify the

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additional argument in the pod definition file.

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Anything that is appended to the docker run command will go into the “args” property of the pod definition

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file in the form of an array like this.

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Let us try to relate that to the docker file we created earlier.

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The Dockerfile has an Entrypoint as well as a CMD instruction specified. The entrypoint is the

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command that is run at startup, and the CMD is the default parameter passed to the command. With the args

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option in the pod definition file

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we override the CMD instruction in the Dockerfile.

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But what if you need to override the entrypoint? Say from sleep to a hypothetical sleep2.0 command? In

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the docker world.

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We would run the docker run command with the entry point option set to the new command the corresponding

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entry in the pod definition file would be using a command field the command field corresponds to entry

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point instruction in the docker file so to summarize there are two fields that correspond to two instructions

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in the docker file.

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The command field overrides the entry point instruction and the args field overrides the command instruction

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in the docker file.

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Remember it is not the command field that overrides the CMD instruction in the docker file.

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Well that's it about commands and arguments in Kubernetes head over to the coding exercises section

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and practice viewing configuring and troubleshooting commands and arguments in kubernetes.