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[Intro Music]

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Now you know that every image is

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read-only, and it has multiple FS

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layers. Now's a good time to create

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a new container based on already

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pulled image. And let's create

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first hello-world container. For

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that, let's use 'docker run' command,

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that will create a new container;

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and afterwards, as argument we

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supply the name of the image we

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want to use, 'hello-world'.

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Recap that this image is already

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located in our local cache, we have

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already pulled it from Docker Hub.

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Great. Let's press Enter. And you

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simply see some text in this

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output. And afterwards, we go back

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to terminal. And that means that

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container is no longer running. It

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has performed some job and that's

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it. And now there are two

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questions. First one, why this

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container has printed this text to

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the terminal? How it knows which

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action to perform when we create

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new container? And second question,

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why this container has exited? Why

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it is no longer running? Actually,

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I could verify that it is not running

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anymore using 'docker ps' command,

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and list of active containers is

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empty. Before answering those

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questions, let me read together

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with you this output, 'Hello from

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Docker! This message shows that

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your installation appears to be

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working correctly. To generate this

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message Docker took following

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steps. First sep, Docker client

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contacted the Docker daemon'. Recap

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that 'docker' command is actually a

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Docker Client. It is a binary file

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located at your computer. And when

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you enter 'docker', along with any

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additional commands, Docker Client

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contacts Docker Daemon, and sends

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this command to it. That's what

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happened under the hood. Next step,

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'Docker daemon pulled hello-world

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image from Docker Hub'. Basically,

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we have already pulled this image,

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that's why this step was skipped.

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Docker has verified that there was

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already a hello-world image located

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in local cache, that's why there is

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no need to pull it from Docker Hub.

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Next step, 'Docker daemon created a

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new container from that image which

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runs executable that produces

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output you are currently reading'.

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That means that Docker has created

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a new container based on hello-

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world image, but what is actually

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container? I'll answer this

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question in the next lecture. But

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let me finish reading this output.

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Finally, 'Docker daemon streamed that

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output to the Docker client, which

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sent it to your terminal'. It means

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that communication between Docker

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Client and Docker Daemon is bi-

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directional. Docker Client sends

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some commands to Docker Daemon, and

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Docker Daemon returns some result,

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and this result was returned

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actually by Docker Daemon, and

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Docker Client has printed this text

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to the terminal. And afterwards

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last step that was omitted here,

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this Docker container was stopped,

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because it has already done

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its job. Now, let me proceed, and

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next let me clarify a bit deeper

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what actually happened under the

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hood, and what is container, and why

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container decides to print such

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text to the terminal. Let me talk

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about it in the next lecture. Bye-Bye.

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[no audio]