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Before we move on there's just one last little quick thing though and show you around this entire image

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building process.

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Now what I'm going to show you inside this section is not something that you're probably gonna do very

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often or ever really but it's something I thought you might find a little bit interesting and help you

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get a little bit of a better handle on the relationship between an image and a container.

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When we were going over the flow of actions that occurred while we were building the image we spoke

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about how we take an image from the previous step we create a container out of it we do something with

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that container and we then essentially create an image out of that running container or that kind of

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very temporally temporary container that was created.

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So at this point you and I know very well that we use images to create containers but based on everything

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that we've been talking about in this section it sure seems like the opposite is kind of true as well.

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It seems like we can kind of take a container and generate an image out of it as well.

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And that actually is correct.

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You and I can manually create a container run some commands inside of it or change its file system and

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then generate a usable image that we can then use at some point in the future.

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In other words we can kind of very manually do the same thing that our darker file does.

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We can create a container run a command like say KPK ad read this right here and then generate an image

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out of that.

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I want to very quickly show you how that would look.

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But again I really don't expect you to do this on your own personal project.

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I'm just showing you this as kind of something you might find interesting.

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So let's try to kind of emulate the docker file that we just put together.

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We're going to create a new container manually out of the Alpine image.

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We're then going to install red lights on it.

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We're then going to set up a default command and generate a usable image that can be used in the future.

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Essentially everything that our Docker file just did.

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So at my terminal I can execute Docker run and we're gonna start up a shell inside of here so that we

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can run a couple of commands inside of it.

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So going to put on the I.T. flag I'll put on Alpine as our image and then the command that I want to

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execute inside there is a safe to start up a shell.

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So then I get presented with a command prompt right here that is inside of that running container.

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And so inside that container I'm going to manually install redness by running a P.K. add dash dash updates.

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Red is like so.

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So we now have a running container where we have modified its file system and a file system has now

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seen the installation of reticence.

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So we've got the running container.

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I'm now going to open up a second terminal window and inside of here I'm going to run a command using

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the docker Seelye.

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That's going to essentially take a snapshot of that running container and assign a default command to

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it and generate an image out of the entire thing.

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So to do so I'll say first Docker P.S. to get the idea that running container and then we'll do Docker

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commit.

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I'm going to add on a dash C right here which is going to allow us to specify the default command.

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So I can say dash C and then I'll put on CMT double quotes inside the square brace red s dash server

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I'll close the double quotes or close the square brace and I'll close the single quote.

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So notice how we have a single quote single quote and double quotes around it.

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And then after all that I'll paste the idea of that running container.

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It's going to paste it in like so and the output is the idea of a new image that we just customized

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for our own uses.

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Now you'll notice that this is a really long idea right here.

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One shortcut that I haven't quite mentioned so far whenever you're making use of ideas or hashes in

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the darker world.

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You don't have to copy the entire thing.

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You can just copy a segment of the start and it's kind of assume that this is going to be unique enough.

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The Docker is going to take this and realize that oh you're probably talking about this very long idea

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right here.

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So going to copy it just an arbitrary number of leading characters here and then we'll do a doctor run

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that.

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And that's going to start up a new container out of the image that we just created.

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And inside that running container we already have redness installed in the default starting command

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will be to run red a server.

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So let's run that and we'll very quickly see all the typical output that we see from a running redis

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instance.

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All right.

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So like I said we basically just very manually created a container added a dependency to the container

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set up the default command and then generated an image out of all that again.

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You really don't want to use that practice in general if you don't use Docker commit in general you

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really want to use the docker file approach because it allows you to very easily rerun that series of

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steps again in the future.

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But again I just thought you might find it interesting how.

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Yes there really is a very kind of fluid relationship between containers and images.

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All right.

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So let's take another quick pause right here and we'll move on to the next section.