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Docker Container Tutorial #2 Making changes to docker images



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hello welcome to another how to code

well YouTube tutorial my name is Peter

Fisher and this is the second part of

the docker image docker container set of

tutorials in this tutorial I'm going to

focus on how we can change and

manipulate a docker image once we have

the image downloaded to the machine in

the previous tutorial in the intro

tutorial I had a discussion on what the

difference is between a docker image and

what the difference is between a

container and the things that define the

two as well as a brief tutorial I

suppose a demonstration of how to pull

down an image and how to run them as

containers or run containers from the

images now I highly recommend you check

that video out the previous one because

it will give you some insight and some

better knowledge for this video also

I've got a docker machines tutorial that

I recommend you you watch too if you

haven't already done so I'll put links

to those in the description and the

YouTube cards up here as I go along but

today we're just going to focus on how

we can manipulate these images once we

have them so I'm gonna ensure that I'm

in the right machine so that's just you

block a machine active and this should

return the how to code well machine

which it does and if we did docker

images we shouldn't have anything here

and if we did docker PS - a we shouldn't

have anything there so you can see I've

got nothing up my sleeve so let's just

clear this down and what I'm going to do

is docker Paul and we're just gonna get

the you burn to the latest Ubuntu image

so this is this step is exactly what we

did in the previous video obviously I

had more explanation as to what I was

doing but we'll just wait until this

gets installed okay so if we did docker

images we can get the image ID alright

so what we need to do is create a

container

this image first before you know in

order to manipulate this image we must

get a container then we create this

container and get into it using a bash

shell then we install some bits and

pieces and then what we need to do is

save those bits and pieces to the image

so we can use it again so the first

thing we do is docker run and - mighty

we've got the image ID here and we're

gonna go in as bin

whoops bin bash so this again will bin

bash this will take me into a shell

which it does and what I can do is do an

apt-get update so that's going to update

the sources and I'm going to install if

I just do a clear I'm gonna install apps

get install and install NPM and p.m. cuz

this is something I use quite frequently

so if we go yes so this is actually

creating changes to the image okay so

this is creating changes to the image on

this docker machine and as this is

running through I would like to just

explain that there are things called

docker files now a docker file is what

what is used to actually create the

images from scratch I will go into those

in more detail in future videos and how

to create daka files and so forth but

the point I want to make is that it's

it's what I'm doing now is on I'm I've

kind of change I'm changing the image

without changing a docker file which in

some cases is okay especially from

committing it back to a registry but

it's always good if you want to start

from scratch to do these changes to have

the the end the apt-get install NPM

command within the docker file as well

so then you can put that into source

control and other developers can use it

but anyway I take your s so let's do NP

n minus V and we can see here we've got

three point five point two

that's fine and I'm just going to exit

out of this container okay so obviously

if I did docker images if I was to

remove this image and then they were

pulled from Ubuntu again I won't have

the NPM because this is something that

I've added myself so what I need to do

is commit this image and I'm committing

it to to my local how to code well

machine so what I do is do docker commit

in fact actually I need to do docker PS

- because you know I said before that

container is a snapshot of an image so

we need to do docker commit - no we

don't docker commit and then the come

the container ID so it's that one there

and we need to give it a name as well so

I'm going to do Ubuntu Ubuntu and I'm

just going to put - and p.m. - 10 p.m.

so what that is going to do after I

press ENTER is it's actually going to

create another image or a snapshot of

that container with NPM in there and if

I was working against a private or a

public public docker registry in which I

could login to I could then do a docker

push and push this or docker tag tag it

and then push it up so if I now did

docker images we can see that we have a

third image here Ubuntu - NPM so that

was the first one that we got the latest

that we got and then this is the one

that we have literally just created so

let's do a docker PS - a I'm just gonna

clear the screen docker PS - a and we've

got so we've got that container that we

were just in I'm gonna do a docker RM

and remove it

because what I want to do is do a docker

images and I want to do a docker run -

IT and I'm going to use I'm gonna use

this image the new image that we've got

and I'm going to run that and actually

what I'm going to do is just run NPM -

fee okay so that will print out the

version of NPM from the container so if

I did that

we should get 3.5 points here which we

do now if I was to do that against the

previous image the image that we first

got from the public registry the Ubuntu

repository so find it NPM if I ran lap

against here we will get an error and

we'll get an error because NPM isn't

installed in that image it is in this

image but not in that image so if I did

that then we get an error a pretty nasty

one and basically that means that the

executable file cannot be found in the

path so I'm just gonna clear that down

and you took off PS - a and likewise if

I was to let's just do a docker RM there

are other ways of actually getting into

these containers using docker Exe but I

will show that to you later on I'm gonna

just kill that and also kill that one

like so so I talked a PS - I think there

go back to docker images so if we were

to do a docker run - I T to the original

image ID so that's the original Ubuntu

image and then if I was to just run that

as bin bash and did a NPM - V we can see

that is tomorrow cannot be found so I'm

going to exit out of you and I'm going

to now jump into being bash in this

image

and paste that in undo an NPM - feat and

we can see it is there so this is how

you create your images where you update

your images and you commit them and like

I said if you have if you were connected

or logged into a registry you could then

do a tag and a push to push this stuff

up it's very important to keep

committing as you go and also like I

said it's very important to have a

docker file that you can update as you

go - just to keep a record of what

you've done I'm going to leave it there

even though there's a lot more to to

this subject I'll probably pick that up

again in in the following tutorials but

if you've got any questions then please

do let me know put them in the comment

section below

like a video if you found it helpful and

please do share it around subscribe to

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the web chats that I do every week so

thanks again for watching and I shall

see you again soon bye