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[Intro Music]

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We have just explored the image

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called BusyBox. BusyBox is

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basically not a full feature of the

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Linux operating system. Instead, it

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is just a set of Linux utils. And

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now in this lecture I will

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demonstrate you how to use another

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image called Alpine. And let's

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first try to pull this image using

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'docker pull' command. We have not

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used this command before, but this

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command will simply pull image from

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Remote Registry Docker Hub. Let's

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do that. At the moment, we actually

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have three images, ubuntu, busybox,

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and hello-world. And now let's pull

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one more image, 'docker pull alpine'

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without any tags, just 'alpine'. And

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you see that we are using the

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default tag 'latest', and we are

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pulling this image from Docker Hub.

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Image was pulled, here is its SHA

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256 Hash. And if I repeat the same

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command again, 'docker pull alpine',

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you'll see that Docker server will

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try to pull the same image again,

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but you'll see status that 'Image is

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up to date for alpine:latest'.

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Basically all what happens here, in

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this case, we are comparing those

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hashes, this one and this one, and if

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the image Docker decides that we

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already have latest image available

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locally in a local hash, and if I

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list images, local images now

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'docker images', you'll see this new

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image, 'alpine' on the list. That is

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latest IMAGE ID is here, CREATED

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'2 weeks ago', and its SIZE is 5.6

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megabytes. Notice that the alpine

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image is larger than busybox

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image, busybox image was a bit

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larger than one megabyte, but alpine

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is still much much smaller

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than ubuntu image, that is 64

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megabytes in size. Now let's try to

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create a new container based on

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alpine image. And afterwards, I'll

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create one more container with

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busybox image. And I'll try to

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compare those two images and show

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you differences between them. But

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basically, alpine is based on

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busybox; and again, I'll prove it

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to you in this lecture. Okay,

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great. Let's first create a new container

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based on alpine image. Let's

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create it like so, 'docker run -

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it', because I need to get into 'ch'

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shell inside of this container. And

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let's type here name of the image

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'alpine' like so. Container was

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created. And I have automatically

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logged into ch shell inside of that

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container. Let's use ls command

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here and you'll see a set of

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folders inside of alpine

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container. Great. Let's in

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parallel, create one more container

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and it will be busybox container.

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Let me open up a new tab here. And

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let's create a new container 'docker

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run -it' again, and here will be 'busybox'.

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Again, I have logged into ch shell

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inside of that container. And if I

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list the folders here, you will see

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less folders than we have seen here

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in alpine container. Now, let's do the

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following. Let's try to explore a

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version of Linux operating system

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here in this container, alpine

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container. Let me clear terminal, and

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type 'cat /etc/os-release'.

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And I'll see release

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version of this container. It is

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Alpine Linux version 3.11.

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And that proves that this

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container is basically running

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Linux operating system. And here

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is the link, you could copy this link,

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and go to your web browser. Let me

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do that quickly. Go to Google

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Chrome, and paste link here, and on

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this page you're basically able to

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read the details about Alpine Linux,

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what is that? And here you actually

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see that Alpine Linux is security-

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oriented, lightweight Linux

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distribution based on musl libc

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and busybox. Okay, now let me show

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you why alpine is actually based on

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busybox and how you're able to

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verify that. Let's list files in 'bin'

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folder, 'ls bin'; and you'll see here

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bunch of actually links to BusyBox

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utilities. Let me execute the same

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command as I had executed before, I mean

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'cat /etc/os-release' in busybox

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container. Let's go to this tab

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where we have started busybox and

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let's type 'cat /etc/os-release',

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same command as we

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have just entered in alpine

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container, Enter, and you'll see this

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error, can't open '/etc/os-release':

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No such file or directory,

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and that proves that BusyBox is not

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basically a full featured Linux

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operating system, it is just a set of

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utilities, nothing else. Let's

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basically compare the contents of

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'etc' folder here in busybox

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container and alpine container.

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Let's list files here, 'ls etc'; and

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let's list files here, 'ls etc'; and

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you'll see here much more files and

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folders than we have seen here in

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this output in busybox container.

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Okay, let's now try to compare

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contents of the 'bin' folders here

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and here. Let's list files here in

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'bin' folder; and let's list files

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here in busybox, 'ls bin'. You'll see

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here much more actually files in

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busybox container than here. But if

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you execute the 'ls -la' command

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'bin', you'll see that all commands

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here in alpine container are

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basically shortcuts for busybox

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commands. You see that, for

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example, 'ps' command is shortcut,

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and it links us to '/bin/busybox'

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executable script. Let me show you

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something. If you simply type

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'busybox' here in alpine container,

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you'll see actually description of

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busybox commands. And if you scroll

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up, you may read that the 'BusyBox

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is a multi-call binary that

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combines many common Unix utilities

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into a single executable'; and this

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executable is included into alpine

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container. That's that simple.

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That's why you are able to use all

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commands that are available in

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busybox inside of the alpine

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container, because of those hard

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coded links. For example, this

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command 'sed', links to be busybox

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command, and so on. You could

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actually try to do that. And for

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example, let's read the help for 'ifconfig'

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command. 'ifconfig --

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help. You'll see this output -

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BusyBox v1.31.1, and

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so on. And description of options

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for 'ifconfig' command. If I will do

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the same in busybox container,

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'ifconfig --help', you'll

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see actually exactly the same

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result - BusyBox v1.31.1,

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and so on. Same result as

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here. And again, that proves that

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alpine image is based on busybox

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image. But there are some

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additional folders and files that

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make alpine image basically a

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fully featured Linux operating

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system. That's how it looks like in

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comparison between alpine and

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busybox images. Great. What else I

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wanted to show you. Let me also

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list the contents of the 'sbin'

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folder here in alpine container.

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Let me actually use 'ls -la sbin'.

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And also in this folder, you

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will see that there are a bunch of

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actually links to '/bin/

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busybox'. Like reboot, that points to

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'/bin/busybox'; 'poweroff', and so on.

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But if I scroll a bit up, let me do

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that, you'll see additional scripts

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like 'ldconfig', 'mkmntdirs', and

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also you should see here 'apk'

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script, let me scroll a bit up,

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yes here it is. And with this

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script, you are able to install

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additional packages inside of the

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alpine container. And if you enter

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'apk --help', you'll see

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actually help for 'APK' command. And

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if you scroll up, you'll see that

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there is no information about

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BusyBox at the top. This is because

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this script was added additionally

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to scripts built in into BusyBox.

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And if I'll go to BusyBox here and

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enter 'apk', I will get answer

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'apk: not found'. And that's because

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'apk' is absent by default in

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BusyBox. Great. Let me also show

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you how you're able to start

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specific scripts using busybox

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scripts. For example, let me clear

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terminal and type here, I am now in

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alpine container, 'busybox ifconfig',

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and you'll get a result of 'ifconfig'

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command using busybox

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script. And again that proves that

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busybox is just a set of

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utilities and you are able to use

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those utilities like so. Or let's

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use busybox, for example, 'traceroute'

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command and here let's trace

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route path to google.com. It seems

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that something is broken on a way

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but anyway let's for example use

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ping instead of traceroute, and you

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will see answer from google.com web

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server. And also you are able to do

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following. You are able to use ping

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without busybox prefix. Simply,

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'ping google.com', and you'll get

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the same result. And the reason for

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that is that ping is simply link to

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'busybox ping'. Let me show you that

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'ls bin', and you'll see ping here

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on the list, but in order to verify

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that it is actually linked to

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busybox, you could use 'ls -la

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bin'; and if you scroll up, you'll

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see that ping is simply link to

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'/bin/busybox'. That's that simple.

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Great. That's the comparison of

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busybox and alpine. And actually,

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alpine is a very popular choice for

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creation of additional images,

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custom images, it is really small

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in size, it is a bit more than five

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megabytes. Let me show you it

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again. Actually, now I'm located in

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alpine container, and I need to go

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out of it. Actually, let me open up

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a new tab and list images here,

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'docker images', and here you'll see

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sizes for alpine image, for busybox

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image, and for ubuntu image. Let's

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shortly summarize what we have

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explored here in this lecture. We

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have compared alpine and busybox

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images. And you have see that the

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BusyBox is basically just a set of

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utilities, nothing else; and Alpine

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is full feature of the operating

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system, that's called Alpine Linux,

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but it's based on BusyBox; and it

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reuses utilities that are included

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in BusyBox. But it also has some

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additional features. For example,

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it has 'apk' utility that allows

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you to install additional packages

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or modules inside of the operating

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system. And Alpine is very often

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used as a base layer for custom

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images. Okay, I hope you enjoyed

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this comparison, and now you

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understand difference between

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Alpine and BusyBox, and now you

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should understand that there was no

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need to use such large images,

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for example, like ubuntu, that is

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much much larger than alpine or

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busybox. And if you just need the

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Linux command line and some basic

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utilities, you could go ahead with

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Alpine. Okay, that's all for this

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large lecture. And in the next one

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let's proceed and explore some

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additional images. See you next bye-bye.

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[no audio]