Introduction

this is part 14 from the journey it's a long journey(360 day) so go please check previous parts , and if you need to walk in the journey with me please make sure to follow because I may post more than once in 1 Day but surely I will post daily at least one 😍.

And I will cover lot of tools as we move on.

Download app_014

if you follow part 9

cd location/DevOpsJourney/app_014/

replace location with where you put the DevOpsJourney

if your new go to part 9 and do same steps will download old lecture files and new one.

The Problem

so the problem with our Docker right now is every time we need to make a change for our code we need to rebuild image , is time and space waste , and not a pragmatic way to do.

Let's see the problem

first let's build our app

docker image build -t app_014 .

and let's run our app

docker run -it app_014

our app will print a message and save a number to a file.txt let's take a look inside our app

it will save number 12 to a file.txt

let's take a look inside our app folder , as we know docker will create an app folder inside his own image because we asked to do this , check # 009 Dockerfile so to access this app folder using interactive shell

docker run -it app_014 sh

inside the interactive shell

cat file.txt

we can see that 12 is stored

Time to make a change

let's change 12 in our app.py to 666 first exit our interactive shell

exit

I use vim as my text editor(actually as complete IDE ;D )

let's take a look again inside the container

docker run -it app_014 sh

inside the interactive shell

cat file.txt

we can see that isn't changed

The fix

we can fix our problem using -v (volume)

docker run -it --rm --name app_014 -v $PWD:/app app_014

$PWD is a default variable in linux it store the home url in our case , we use in docker alpine which is a linux based distro , /app is the directory we make in Dockerfile to store our app again let's take a look inside

docker run -it --rm --name app_014 -v $PWD:/app app_014 sh

inside the interactive shell

cat app.py

as we see we got 666 without rebuild our image!

let's try 999

see as soon I change my code is got updated inside the image with out rebuild the image.

This post is also available on DEV.