Welcome back and in this part of the course,


I want to demonstrate a really simple interaction


between the Docker client and the Docker Daemon.


Now what we're going to do is


use the Docker command line interface


to run a sample container


and it's going to be a container called Hello World


which is provided by Docker.


And this is going to demonstrate part


of the process that's shown on screen now.


So we're going to go ahead and download a Docker Image.


Then we're going to use that Docker Image


to spin up a container


and show you how to interact with that container.


So let's go ahead and get started.


To do that, we need either the command line


or the terminal open


and we're going to use the Docker command.


So specifically we're going to use Docker, space, Run


because we're going to run a container


and the container we're going to run is Hello hyphen World.


Now, before we run this command,


we don't currently have any containers or images


on our local machine.


And I can demonstrate that by running Docker space PS


and press enter.


And that's going to list any containers running


on this Docker Host.


And as you can see by the fact


that we just have this empty line,


we don't currently have any containers running.


I can also show any Docker images that are downloaded


onto this Docker Host by running Docker space images.


And as you can see, we have none.


So this is a clean Docker Host.


So now I'm going to use Docker space Run space,


hello hyphen World, and press enter.


Now that that's completed,


I want to step through exactly what happened.


So I'm going to scroll up.


So first,


the Docker client tells us that it's unable


to find an image Hello hyphen World:latest locally.


This means that this image is not stored on our Docker Host.


So hello hyphen World is the name of the image


and then this colon latest is a tag.


And this just means the latest version of this image.


So because it can't find this image locally, it's going


to pull this image down to our local machine.


So it's gonna pull the latest version of Hello Hyphen World


to this Docker Host.


Then we're told the pull is complete.


So this image is now running locally on our Docker Host


and then it runs a container using this image


and we get this output, Hello from Docker.


It also as part of this Hello message,


outputs the steps


that we used as part of running this container.


So it tells us that Docker client contacted


the Docker Daemon.


The Docker Daemon pulled Hello World from Docker Hub.


The Docker Daemon started a new container from that image


which is running the executable that produces the output


that we're currently reading.


And then the Docker Daemon streamed that output


to the Docker client, which sent it to your terminal.


So in short, what we've done is pulled an image


from Docker Hub to our local Docker Host


and we've used that to run a container.


Now, you could have pulled the image separately


by using Docker pull


and then run a container using Docker run.


But if you just run Docker run on its own


and you don't have a copy of the relevant image,


then it pulls that image automatically.


So I'm just gonna clear the screen to make it easier to see.


And then I'm going to run a Docker space PS


and note that we don't see any running containers


and that's because the container that we've just run,


all it did was output that text and then stopped.


We can run a Docker space PS space hyphen A,


and this will show any containers


which were previously running.


So in this case, we can see


that three minutes ago we ran a container


with this ID using the Hello hyphen world image


and it also exited three minutes ago because remember,


all this container did was output the text that we saw


on screen and then exit.


I'll clear the screen and then run a Docker space images


and this will show us any images which are locally stored


on this Docker Host.


Now, because we didn't have a copy


of the Hello hyphen world image


when we tried to run a container using this image,


it automatically downloaded this image


to our local Docker Host and we can see Hello hyphen world.


Now, this is a really simple interaction


between the Docker client,


the Docker Daemon, and Docker Hub.


Don't worry, we're going to go into a lot more depth


as we move through the course,


but I want you to start off being really comfortable


with simple interactions


with the Docker Daemon, and that's what I've demonstrated


in this part of the course.


We've used Docker run to download an image


and run a simple container.


We've used Docker PS to list any containers


and we've used Docker PS hyphen A to list all containers


including those which are stopped.


We've also used Docker images to show us any images


which have been downloaded


to our local Docker Host from Docker Hub.


Now at this point, that's everything I wanted to cover


in this part of the course.


Again, don't worry, we're going to be going


into significantly more depth


as you move through the course.


I just want to start introducing these concepts one


by one so we can build


on the knowledge as you move through the course.


But at this point, that's everything I wanted to cover


in this part of the course.


Go ahead and when you're ready, I'll look forward


to seeing you in the next part of the course.