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So now with all that information

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about volumes and bind mounts,

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there is one question which might've come to your mind

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and it's related to the stalker file.

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If we run a container with our Docker run command,

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which we used all the time, this command,

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we bind our entire folder here as a bind bound

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to make sure that changes in our code

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are automatically reflected in the running container.

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Now why do we then still copy in

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everything here in our Docker file?

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I mean, if we use the entire folder as a volume,

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as a bind mount anyways, why do we copy in this snapshot

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when the image is created?

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It's going to get overwritten anyways.

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Yes we keep the node modules folder,

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but we don't copy that in.

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We create that with the NPM install.

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So can't we remove this copy step?

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Well, yes, we could do that.

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If I command this out and I rebuild this image,

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so if I build this image again

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with a target of feedback node, no copy for example,

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if I do that and I wait for this to finish,

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I can definitely run this container again.

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Now using that no copy tag here after the image tag,

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after the image name,

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and you will see that this still works fine.

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This works, everything works here.

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We can also of course view this created file here.

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So that works.

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So yes, we could remove this if we use a bind Mount,

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but there's one important thing about bind mounts,

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which you must not forget.

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This Docker run command

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is the command we use during development.

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We use this bind Mount during development

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to reflect changes in our code,

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into running container instantly.

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Once we're done with developing,

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and once we actually take this container,

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put it onto a server and we want to run it here,

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we will not run it with this command.

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We will definitely not run it with a bind Mount.

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We might use other volumes to ensure that data survives,

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but will not use this bind Mount.

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Because if the container is running in production

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on a server, there is no connected source code,

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which updates while it's running.

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We will definitely not do that.

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In production,

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we always want to have a snapshot of our code,

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and that's why I keep copy here in the Docker file.

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I still want to be able to create snapshot images.

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So images with snapshots of our code,

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which we then could use to spin up production,

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ready containers.

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If in addition during development,

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we want to have a bind Mount, that's fine, it works.

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But we definitely need the option of

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creating a snapshot container for production.

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I am aware that we haven't learned how to deploy a container

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yet, but we will get there later in the course.

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Still I hope this makes sense.

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And it's clear why we still want to copy in the Docker file.