Introduction to docker

Here are some useful tips to use docker.

Image

In docker’s term, each program to execute is called “image”. From dockerhub, it is possible to view available images that I need.

docker pull httpd # Pulls images named "httpd"

To check images in my computer, run:

docker images # make container and run http image

Container

In docker’s term, environment that programs are executed is called “container”.

Run

To make a container that runs image, type:

docker run http # make container and run http image

Running with customized name:

docker run --name tommy httpd # named "tommy"

To use docker container in web server, you need to run:

docker run --name tommy -p 8080:80 httpd # User access port => [IN]:[OUT] <= container access port

To synchronize file system,

docker run --name tommy -p 8080:80 -v ~/Desktop/repo:~/home/repo httpd # synchronize client and host folder

Run in script: Docker-compose

If a command to run container is lengthy, such as,

docker \
run \
    #[very long command]
mysql:5.7

these commands can be formed into a file called “docker-compose.yml”.

This file can be run using:

docker-compose up

and be shut down using:

docker-compose down

Do something in container

Using exec command with -it option, command can be run iteratively.

docker exec -it tommy /bin/bash # in container "tommy", exec bash interface (-i) tty (-t)

Check Process

PS \home > docker ps -a
REPOSITORY        TAG                             IMAGE ID       CREATED         SIZE
httpd             latest                          a8ea074f4566   2 weeks ago     144MB

Stop

To stop container,

docker stop tommy
docker stop [containerid]

Restart

To restart container that was stopped,

docker start tommy

This does not show logs. If you need logs, take:

docker logs [-f] tommy # showing logs, -f will show logs in live

Remove

To remove containers,

docker rm tommy

Customize your container and publish

Pull base image and customize

As an example, Let’s install git in ubuntu image.

docker pull ubuntu # pull
docker run -it --name my-ubuntu ubuntu bash # run and bash
apt install git # install git

Commit

To create new image, we can commit this.

docker commit tommy my-ubuntu:my-ubuntu-git 

Customize image using script : Dockerfile

However, customizing may have complicated procedures; That’s why we have Dockerfile.

In file named “Dockerfile”, write something like:

From ubuntu
RUN apt update && apt install -y git

Build

Using Dockerfile, we can build a new image as follows:

docker build -t carrtesy:ubuntu-git-in-dockerfile . # [path to Dockerfile]

Push

To make your image public,

docker push carrtesy/python3:1.0 # push to [dockerhub account]/[repository name]:[version]

References

Basics

[korean] 생활코딩 / Docker 입구 수업 / https://www.youtube.com/playlist?list=PLuHgQVnccGMDeMJsGq2O-55Ymtx0IdKWf

Advanced

[korean] 생활코딩 / 도커 : 이미지 만드는 법 - commit / https://www.youtube.com/watch?v=RMNOQXs-f68&list=RDCMUCvc8kv-i5fvFTJBFAk6n1SA&index=1

[korean] 생활코딩 / 도커 : 이미지 만드는 법 - Dockerfile & build / https://www.youtube.com/watch?v=0kQC19w0gTI&list=RDCMUCvc8kv-i5fvFTJBFAk6n1SA&index=2

[korean] 생활코딩 / Docker hub로 이미지 공유하기 (push) / https://www.youtube.com/watch?v=_38dU6GExDo

[korean] 생활코딩 / Docker compose 를 이용해서 복잡한 도커 컨테이너를 제어하기 /https://www.youtube.com/watch?v=EK6iYRCIjYs