Docker Manual

Written by SGLee, VCANUS

Setup

Installation

CentOS

$ sudo yum install -y yum-utils \
  device-mapper-persistent-data \
  lvm2
$ sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

특정 버전 설치

$ yum list docker-ce --showduplicates | sort -r
$ sudo yum install docker-ce-<VERSION_STRING> docker-ce-cli-<VERSION_STRING> containerd.io -nobest

최신 버전 설치

$ sudo yum install docker-ce docker-ce-cli containerd.io nobest

Ubuntu

$ sudo apt update
$ sudo apt install apt-transport-https ca-certificates curl software-properties-common
$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable"
$ sudo apt update
$ apt-cache policy docker-ce
docker-ce:
  Installed: (none)
  Candidate: 18.06.1~ce~3-0~ubuntu
  Version table:
     18.06.1~ce~3-0~ubuntu 500
        500 https://download.docker.com/linux/ubuntu bionic/stable amd64 Packages
     18.06.0~ce~3-0~ubuntu 500
        500 https://download.docker.com/linux/ubuntu bionic/stable amd64 Packages
     18.03.1~ce~3-0~ubuntu 500
        500 https://download.docker.com/linux/ubuntu bionic/stable amd64 Packages
	
# Installed: (none) 이면 docker 설치
$ sudo apt install docker-ce

Start docker on boot

A file of docker.service is already installed on /usr/lib/systemd/system.

$ sudo systemctl enable docker.service
$ sudo systemctl start docker.service
$ sudo systemctl status docker.service
$ sudo usermod -aG docker $USER

Start docker container on boot

Refer some documents about service registration. The below make a docker container to be run automatically on boot.

$ sudo vi /etc/systemd/system/docker-container.service

docker-container

[Unit]
Description=Docker Container Service
Requires=docker.service
After=docker.service

[Service]
#Type=alyways
RemainAfterExit=yes
ExecStart=/usr/bin/docker start docker_container_name # <- modify here
ExecStop=/usr/bin/docker stop docker_container_name # <- modify here

[Install]
#WantedBy=default.target
WantedBy=multi-user.target

$ sudo systemctl start docker_container_name.service
$ sudo systemctl enable docker_container_name.service

docker-compose

1. add option restart: always

2. example file(nats-node-1.yaml)

   version: "3.5"
   services:
     nats-node-1:
    network_mode: host
    image: nats
    restart: always
   

   Run services inside docker container on boot

   make entry-point script (docker-entrypoint.sh).

   • sleep prevents docker service from stopping after exit of script.
   • You have to use ‘exec’ instead of ‘attach’ because of sleep.

     #!/bin/bash
     service service-name start
     while true;
     do sleep 1d;
     done
     

run entry-point script

$ docker run -itd --name docker-container-name -p ##:## -v /opt/service/data: /data/ /bin/bash/ -c 'docker-entrypoint.sh'

execute bash with root

$ docker exec -it -u root docker-container-name /bin/bash 

good example of docker-entrypoint.sh

# first arg is `-f` or `--some-option`
# or first arg is `something.conf`
if [ "${1#-}" != "$1" ] || [ "${1%.conf}" != "$1" ]; then
	set -- redis-server "$@"
fi

# allow the container to be started with `--user`
if [ "$1" = 'redis-server' -a "$(id -u)" = '0' ]; then
	find . \! -user redis -exec chown redis '{}' +
	exec gosu redis "$0" "$@"
fi

exec "$@"

Docker Command

https://docs.docker.com/reference/

Basic command

• pull
• images
• rmi
• rm
• ps
• build (important)
  • https://docs.docker.com/engine/reference/commandline/build/
  • refer how to make Dockerfile on the web
• run
  • https://docs.docker.com/engine/reference/commandline/run/
  • options

      --interactive, -i
      --detach, -d
      --tty, -t
      --user, -u
      --volumn, -v
    

• attach
  • https://docs.docker.com/engine/reference/commandline/attach/
  • Description: Attach local standard input, output, and error streams to a running container
    To stop a container, use CTRL-c. This key sequence sends SIGKILL to the container. If –sig-proxy is true (the default),CTRL-c sends a SIGINT to the container. If the container was run with -i and -t, you can detach from a container and leave it running using the CTRL-p CTRL-q key sequence.
• exec
  • https://docs.docker.com/engine/reference/commandline/exec/
  • options

      --detach , -d
      --env , -e 
      --interactive , -i 
      --tty , -t
      --user , -u
      --workdir , -w
    

    Reference

• http://pyrasis.com/Docker/Docker-HOWTO
• http://raccoonyy.github.io/docker-usages-for-dev-environment-setup/

Dockerfile command

https://docs.docker.com/engine/reference/builder/

Basic command

• FROM

   FROM <image>[:<tag>] [AS <name>]
  

• MAINTAINER
• COPY
• RUN

   RUN ["executable", "param1", "param2"]
  

• CMD

   CMD ["executable","param1","param2"]
  

• ENV
• ADD

   ADD [--chown=<user>:<group>] ["<src>",... "<dest>"]
  

   ADD test relativeDir/          # adds "test" to `WORKDIR`/relativeDir/
   ADD test /absoluteDir/         # adds "test" to /absoluteDir/ 
  

• ENTRYPOINT
  • An ENTRYPOINT allows you to configure a container that will run as an executable.

     ENTRYPOINT ["executable", "param1", "param2"]
    

  • ‘List’ type is much more preferred than ‘Shell’ type
  • CMD is used to set argument of ENTRYPOINT

     #!/bin/bash 
     INTERVAL=$1 
     while true; 
      do ps x; 
      sleep $INTERVAL; 
     done
    

     FROM ubuntu 
     Add loop.sh /usr/local/bin/loop.sh 
     ENTRYPOINT ["/usr/local/bin/loop.sh"] # exec form CMD ["1"]
    

• VOLUME

  Reference

• http://pyrasis.com/book/DockerForTheReallyImpatient/Chapter07/06
• https://bluese05.tistory.com/77
• https://joont92.github.io/docker/volume-container-%EC%B6%94%EA%B0%80%ED%95%98%EA%B8%B0/

Docker compose

Preparation

• docker-compose.yml
• Dockerfile
• docker-entrypoint.sh (shoulb be executable)
• xxx.conf

  Run

  $ chmod 755 docker-entrypoint.sh
  $ sudo docker-compose up --build -d
  

  example: docker-compose.yml

  version: '3'
  services: 
  redis1: 
    image: redis:5.0.6 
    build: 
      context: .  
      dockerfile: Dockerfile 
      args: 
        - EXPOSEPORT=7001 # this will be used in Dockerfile
    network_mode: "host" 
    environment: 
      - CLIENTHOST=192.168.XX.XX 
      - CLIENTPORT=XXXX 
    volumes: 
      - ./data/1:/data 
    restart: always
  

  Docker-based Redis Cluster

  https://github.com/sglee-net/docker-redis-cluster

Reference

• http://raccoonyy.github.io/docker-usages-for-dev-environment-setup/
• https://success.docker.com/article/use-a-script-to-initialize-stateful-container-data

Docker Swarm

Reference

• https://tech.osci.kr/2019/02/13/59736201/