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So by now we talked about volumes a lot.

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I hope it's clear why we use them

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and when you use which volume type

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or when you use a bind mount.

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Now I did say that volumes are managed by Docker.

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And this is true.

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When we run our container, as we did before,

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with all these dash V flags here,

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Docker we'll actually go ahead and create that volume,

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which also means that it creates a folder

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somewhere on the host machine automatically.

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It does this without us giving any extra instructions.

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Nonetheless, you can take a look under the hood

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and see what Docker actually did.

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Now here, I have my containers still up and running,

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and now if I type docker volume dash dash help,

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we'll see a couple of commands we can use

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together with docker volume, to have a look

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at all the volumes Docker's managing for all our containers.

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In this case, we have only one container

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but of course we could have multiple containers

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and then we could view all the volumes by all containers.

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So here we got various commands.

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And right now the LS command is interesting.

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It lists all the currently active volumes.

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And if I run this, we see that we got free volumes here.

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Two anonymous volumes, which you can tell

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by this super long cryptic name and one named volume.

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And that makes a lot of sense

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if we have a look at our docker run instruction.

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There, we have one named volume,

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this one here.

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And we did assign a name of feedback,

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which is why we see this name here.

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And then we have the anonymous volume for app node modules

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and the anonymous volume for app temp.

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So two anonymous volumes.

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The bind mount does not show up in this list

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because the bind mount is not a volume managed by Docker.

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As I said and mentioned earlier, this binds a local folder

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which we know, to a folder inside of the container.

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And of course therefore Docker does not manage this.

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It's our known folder on our host machine,

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Docker is not in control over that.

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But the other volumes are managed by Docker

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And managed by Docker also means

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that Docker will create this volume

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if it doesn't exist yet, when you run a container.

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You actually can also use docker volume create

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to create a volume on your own.

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If we enter dash help here, we see that we can specify

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a couple of options here

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though we don't have that many

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and these are advanced options, which we can ignore here

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and then your volume.

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So you can, for example, use docker volume create

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to create a volume named feedback files.

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And if you do that and you then run docker volume LS

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thereafter, you see that volume as well.

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And if you would now run your container

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you could also use this new feedback dash files volume here

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as a name for the named volume, instead of feedback.

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Now, if you don't create the volume in advance,

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Docker will create it for you,

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but you can also create it manually

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if you would like to do that.

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Often, of course, you'll leave it up to Dockerfile

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because since it creates automatically

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if you don't have a strong reason for doing it manually,

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why would you do it?

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Nonetheless, it is worth knowing that you can control this

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with the docker volume command.

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Now with this command, you can actually do more.

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You can also remove a volume

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or remove all unused local volumes

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and you can also inspect the volume.

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Now let's inspect first.

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So first of all, I'll list my volumes.

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And then I'll take this feedback volume here

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and run docker volume inspect feedback

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to look into this volume.

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And now we see some information about this volume here.

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We see when it was created, we see which drivers used

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which we can ignore here.

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And we see its name, possible options that are set up,

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nothing fancy here.

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And then also the mountpoint.

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And that's actually the path on our host machine

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where this is stored.

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I mentioned that Docker creates this automatically for us.

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Well, here is where it created this.

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Nonetheless, this is not a path

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you will find on your system because

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this is actually inside of a little virtual machine

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Docker set up on your system, so to say.

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If there is a basic virtual machine

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in which Docker runs, you could say

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and this is the path in that machine.

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It's not an actual path in your file system

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on your host machine.

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There, this virtual machine is then again mapped differently

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and that's what I meant with,

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it's hard to find out where this is actually stored.

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Therefore, of course, if you just inspect a volume

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to find out where it's stored,

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you're not going to be too happy.

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But if you, for example, wanna see if it's read only

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then you could inspect this because you would see this here

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under options, if it would be a read only volume.

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Which this one of course isn't

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which is why we don't see anything related to that here.

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Now, I said we can also remove volumes.

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And for example, we can remove the feedback files volume

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I created a couple of seconds ago

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with docker volume RM, and then the volume name.

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If I try to remove feedback though

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I get an error because this volume is currently in use.

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Of course, we got an active container based on that volume.

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So we should first stop feedback dash app, this container

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and there after, we will be able to remove this volume.

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Though of course you should keep in mind that with that

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we're going to remove all these text files

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that were created with our app.

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So we're removing all that data which we wanted to save

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across container restarts.

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So that is something you should be aware of.

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When you remove a volume, all the data in it is lost.

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And if you then create the same volume again,

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so a volume with the same name,

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that will not bring back your data of course.

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Still I'm going to do it here

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so did I can show this to you,

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but now if I restart my container

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with this docker run command, you will note

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that if I go there and I try to view feedback.awesome.txt

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we fail to get to this file because

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I removed the volume in the mean time.

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Now we can also use docker volume prune

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to remove all unused volumes

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in case you had multiple volumes

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you wanna get rid off.

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Now, I'll again stop my feedback app container here.

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And then I'm going to list all my volumes again.

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And we only see the newly created feedback app

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which was created because I restarted the container

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after I last deleted it.

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What you also see is

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that the anonymous volumes are missing here

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because as I explained earlier

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anonymous volumes are automatically removed

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if the container for which they were created is removed.

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And this container is removed when it's stopped

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because of dash dash RM option.

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Well, and that finally is it about volumes

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and what you should know about volumes up to this point.

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I know it's a lot, the most important thing

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is that you remember

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how they work and why you use them.

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And that you will remember how they can override each other

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so to say.