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[Intro Music]

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Well, let's go on. In the

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previous lecture we have created

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the container using ubuntu image.

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And here you see that its size is

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around the 65 megabytes. It is

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large in container world. And here

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in this lecture I will demonstrate

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how to use another image called

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busybox.

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But before doing that, let me

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quickly summarize what we have

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learned in the previous lecture.

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You have seen that if you simply

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create container using 'docker run

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ubuntu' command, you will basically

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see that container will be created

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but it will be exited

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automatically. That's because

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process inside of that container

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will be terminated automatically;

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and if there are no processes

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running, Docker will terminate such

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container. It is a first important

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outcome. Secondly, you have seen

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that with option '-it', basically

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it is a combination of two

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different options, '-i' and

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'-t', bit later I will explain

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you what those options mean, you

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were able to get access to bash

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shell inside of the Ubuntu

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container. And as soon as you are

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logged into the container, it will

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be still up and running. And we

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were able to execute some basic

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commands and for example, we have

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listed the contents of the 'bin'

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folder inside of the 'ubuntu'

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container. But as soon as we exited

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from bash shell, container was

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terminated; and the reason for that

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is the same as before, process bash

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was terminated, there were no

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another processes running, and

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Docker has terminated such

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container. That's that simple. Also

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here in this output, you currently

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see that there are two different

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images available locally - ubuntu

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and hello-world. And if you want to

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create any container using already

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existing images in your local

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cache, then there was no need to

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pull those images from Remote

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Registry Docker Hub. Great. Let's

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now get to our third example where

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we will use busybox image, and let's

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do the same as we have done with

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ubuntu image, and let's simply type

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'docker run busybox', Enter, again,

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Unable to find image 'busybox'

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locally; and now we are pulling such

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image from a Remote Registry from

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Docker Hub. Pull complete; Digest is

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here, and Status: Downloaded newer image

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for busybox:latest'. Basically, let

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me shortly explain you what the

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':latest' here and here means

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each image has specific tag. And

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this 'latest' here and here is

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actually tag. If you don't

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specify a tag for specific image

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you want to use, here we have

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specified simply name of the image

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'busybox', Docker will append that

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'latest', 'latest' is usually latest

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stable version of each image. But

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you are able to use different tags

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and usually same image may have

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multiple different tags. And we

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will look at it a bit later. For

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now please understand that this is

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simply tag. And if you don't

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specify a tag for image you want to

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use, then that 'latest' will be added

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automatically. Great. We have tried

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to run busybox container, and again

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we have returned back to our

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terminal. And behavior here is the

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same as we have observed when we

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were running ubuntu image. And if I

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will enter 'docker ps' now, you'll

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see that there were no containers

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currently running. But if I enter

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'docker ps -a', you'll see that

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there was a busybox container that

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was exited, in my case five minutes

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ago. And the fourth command that

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was executed was 'sh' command. 'sh'

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is basically also shell same as

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with bash, but you see here that

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there was no path to '/bin'

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folder. We have simply executed

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under the hood 'sh' command. Great.

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Let's now try to enter this

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container using '-it' option. Let

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me clear terminal and run

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container like so. 'docker run -

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it busybox'. In such case we will not

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again pull busybox image from

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Remote Registry because it's

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already present in our local cache.

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OK, enter and we are now inside of

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the busybox container. And if I'll

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enter 'docker ps' now in another tab,

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'docker ps', you will see that there

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is busybox container running right

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now and it is 'Up 40 seconds'. Okay,

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let's now use the 'ls' command and

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see whether such command is

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available inside of this container.

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'ls', and yes, this command is here

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But you see much shorter list of

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folders than we have seen in ubuntu

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container. Let's have a look at

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contents of the 'bin' folder 'ls bin',

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and you'll see such a list of

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executables here inside of the bin

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folder. And for example, if you try

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to find the 'echo' command, it will

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be present here as well. And you

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are able to use it of course, 'echo

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"Hello from Busybox"

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and Enter, and you'll see, "Hello from

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Busybox" here in this shell. Also,

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let's try one more command, for

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example 'uptime'. You see that this

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command should be present here on

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this list. Let me scroll a bit up

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and here was this command 'uptime'.

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Let's press Enter. And you'll see

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uptime of this Linux container, it

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is up around six minutes. Also, it

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has such commands as 'mkdir', you're

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able to create a new folder. For

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example, let's create 'my-

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folder'. Let's 'cd' into 'my-folder'.

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And here let's create a new file

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'touch file.txt'. And you'll see

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that new file was created. It means

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that this container has a really

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nice set of utilities that you are

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able to use out of the box. Also,

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if you want, you're able to install

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additional utilities if you need to

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do so. But what is actually BusyBox?

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BusyBox is a really small

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distribution that has a really

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large set of utilities, but those

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utilities are custom, and they are

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actually really small in size. And

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usually this BusyBox installation

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is packaged as a single executable

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file. And now let's have a look at

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the size of this busybox image in

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comparison to ubuntu image. Let's

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exit this container like so. And if

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I list the containers that are

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running right now, you'll see that

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there are no containers. Let me do

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that. 'docker ps'. Yes, there are no

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containers currently running,

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because we have exited the 'sh'

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process, and container was

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automatically terminated. And if

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I'll have a look at the history,

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you'll see that there was busybox

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container that was exited 19

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seconds ago. Great. I wanted to

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show you size of busybox container.

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Let's clear terminal and list local

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images, 'docker images'. And you'll

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see a ubuntu, busybox,

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hello-world here on the list. And

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now have a look at the size of

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busybox image. It is a bit larger

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than one megabyte. In comparison to

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ubuntu size this size is really

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really insanely small. That's the

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smallest Linux container available.

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It has again a built in set of

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utilities, and you are able to use

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them but it is much much much more

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smaller than ubuntu image. Great.

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That's how you're able to create

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containers using busybox image.

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Let's now proceed, and next let me

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show you one more image that is

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based actually on busybox image, and

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that image is called alpine. Let's

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have a look at it next. Bye-Bye.

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[no audio]