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Now the good news is that there's only

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a few things left which I wanna explore it with you.

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And the first thing takes us back to the images.

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This image contains your code

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and the application environment.

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That's what you'll learn throughout this course.

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That's why it's quite big.

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The running container is then actually not really that big,

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it's just an extra thin layer,

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the command layer basically, added on top of the image.

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So, this image code is used in the running container.

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it's not copied again, just to make this clear.

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The container builds up on the image,

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and multiple containers running based on the same image

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will share the code inside of the image.

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That's why this code inside of the image is also locked in

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and read only containers can only make changes,

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And for example, create files inside of

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that new extra thin container layer that was added on top

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of all the image layers.

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So, that's how that works.

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But if you wanna know more about an image,

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you also got a command for that,

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you got the Docker image inspect command,

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to which you can pass an image ID.

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And if you do so, you'll see a long output there

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with information about this image.

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And let's go through this output

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from top to bottom, to get a feeling

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for some important things you can learn from there.

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You for example, find the full ID of the image,

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you find the created date,

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to see when exactly this image was created.

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You see configuration for containers that will be executed

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that will be started based on the image,

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for example, which ports will be exposed,

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some environment variables

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which are set in this case automatically,

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and also the entry point, which by default is your command,

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If you don't specify a custom entry point.

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You see which Docker version is being used.

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And a bunch of other things

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which are not too important here.

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But further down you, for example, see the operating system

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which is being used, in this case

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because we're building up on the node image,

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which in turn builds up on

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some Linux operating system image.

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And if we scroll down further,

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we also see the different layers of this image.

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And keep in mind the different commands,

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make up the layers of this image.

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Now here we got 123456 instructions in front of command.

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But of course, we got more than six layers here.

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The reason for that is that it's not just

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about the layers defined in our Docker file.

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But we also automatically have two layers,

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provided by this node base image which we're using.

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So, our image uses all those layers in the end.

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Which of course makes sense

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because if the node image would change internally,

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that also should lead our image to not use caching,

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But to rebuild itself,

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if we would run the build command again.

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That's why we also have two layers

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from the base image we're using.

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And that's the inspect command,

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which you don't need all the time.

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But which can be interesting from time to time,

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to see how your image is configured.

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And how the containers you'll start based on this image,

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will be configured.

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Just in case you forgot or maybe

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because you pulled in some other image,

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from some other source, and you wanna look into it

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and see some general configuration.

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For example here, we could do that for denote image.

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We can of course also run Docker image inspect

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on that image.

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And now we see the configuration of that image,

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just in case you should be interested in that.

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So, that's how you can inspect images and look

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into them after they have been created.