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[Intro Music]

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Alright guys, I have just explained

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you how to use the '-t' option

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along with container run command.

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And now you know difference between

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'-i', '-t' and '-it' options.

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And we have actually tried the

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different variants with 'docker run'

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command. Now it's time to start the

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creation of multiple containers

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using the same image. And in this

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lecture I'll create two

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containers using ubuntu image, and

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I'll demonstrate that those

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containers are completely two

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different containers, and they are

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fully independent, except the fact

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that they basically share resources

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of Docker host, I mean the CPU

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resources, RAM, and disk. Great.

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Let's get our hands dirty, and

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let's create first container based

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on ubuntu image. 'docker run -it',

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I used those two options here,

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'ubuntu', because I want to log in

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into that container, basically into

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the default process called 'bash'. Let's

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press Enter, and now I'm inside of

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the container. That is the first

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container that we have just

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created. Let's for example, list

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files here. And let's, for testing

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purposes, create a new folder here

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called 'test'; 'mkdir test'. Let's 'cd'

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to this 'test' folder; and let's

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create here file 'touch test.txt'.

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And let's go back out of this

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'test' folder. And if I list files

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and folders here, you'll see this

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'test' folder here on the list.

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Wonderful. Let me now create one

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more container based on the same

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image, ubuntu. Let me open up a new

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tab. Basically, let me drag this

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tab here and put those two tabs

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side by side, like so because I

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want you to see differences between

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those two containers. Okay, here is

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the first container with ubuntu

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image; and here in this container,

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we have created a new folder called

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'test'; and inside of that folder

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there was file called 'test.txt';

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and here in this window, let me

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start one more container based on

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the same image ubuntu. Same command,

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'docker run -it ubuntu'.

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Container was started. And notice

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that there was difference in

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container IDs. Here was actually ID

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of this container; and it is

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automatically taken as the host

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name of this container, of this

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computer actually; and here is

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this ID that was used for this

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container number one. Great. Let's

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now list files and folders inside

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of this container, 'ls'; and you'll

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see same set of folders and files

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that we have seen here in this

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container before creation of the

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'test' folder; and there was no 'test'

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folder inside of this container.

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This shows you that every container

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has its own separated file system.

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And file systems of different

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containers don't overlap. They are

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completely independent. But of

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course, those file systems are

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stored on the same Docker host. In

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this case, Docker host is virtual

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machine inside of which those

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containers are run. And this virtual

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machine is basically running on

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this macOS computer, same picture

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for Windows computer. Great. I

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could also create the some files

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and folders inside of this

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container. And let me do that

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quickly. For example, I could

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create a folder called 'test2', 'cd'

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to 'test2'; and here let's create

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the file 'test2.txt'. Let's list

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files here. You'll see 'test2.txt'

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file inside of 'test2' folder,

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and if I'll 'cd' out of this folder,

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you'll see 'test2' folder here in

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the root of this container. And

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again, if I repeat the same command

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here, in container number one, you

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will see that there was still 'test'

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folder and no 'test2' folder.

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Great. That is the difference

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between this container and this

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container. And now you see that the

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containers are fully independent

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and they again only share CPU

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resources of the Docker host and

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RAM. It means that each of those

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containers may take up to 100%

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resources of the Docker host. And

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of course there is possibility to

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limit the maximum size of resources

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that each container may utilize.

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And we will get back to that later

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on in this course. Also, you'll see

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that those containers have

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different host names. And actually

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you could verify hostname by typing

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the 'hostname' command like so, and

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you'll see a hostname of this

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container, and actually this host

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name is shown here after login

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into the container, and if you would

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like to check hostname here on this

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container you could use same

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command 'hostname', and you'll see

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hostname of this container. We

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could also verify IP addresses of

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every container, and for that you

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could use command 'hostname -i',

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and 'hostname -i' in this

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container, and you'll see that those

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containers have different IP

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addresses. But they are basically

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from the same network. And it is

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default bridge network inside

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of the Docker host. Great. That's

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how those containers differ. And

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the goal of this lecture was to

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demonstrate to you that containers

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are fully independent, and have

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different file systems. Let's now

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proceed and in the next lecture,

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let's develop this topic, and let's

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try to create two different nginx

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servers that will host different

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files from different folders. And

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again, that will prove that you are

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able to create multiple containers

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based on the same image. And one

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more thing here that I wanted to

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tell you is that in this case, you

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were not prompted to download any

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new image, something else, image was

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already in your local cache, and it

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was simply reused for both

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containers. That's why you have

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created those containers pretty

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fast, in a matter of seconds. And of

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course, if I will create a new

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container, ubuntu container now, it

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will get the clean file system

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without any 'test' or 'test2'

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folders that we have created in

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previous containers. Wonderful.

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Let's now proceed and next let's

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create the two nginx containers

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with two different set of files.

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See you next. Bye-Bye.

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[no audio]