cheatsheet docker

create docker.json first

nano /etc/docker/daemon.json

{
    "data-root": "/mnt/raid/docker",
    "default-address-pools":
    [
        {"base":"172.17.0.0/16","size":24}
    ]
}

Note

"data-root" can be declared if different default location as /var/lib/docker is desired

"default-address-pools" is recommended to have all subnet created in class b network

install docker for debian

1. set up docker's apt repository

   # Add Docker's official GPG key:
   sudo apt update
   sudo apt install ca-certificates curl
   sudo install -m 0755 -d /etc/apt/keyrings
   sudo curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc
   sudo chmod a+r /etc/apt/keyrings/docker.asc
   
   # Add the repository to Apt sources:
   echo \
     "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian \
     $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
     sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
   sudo apt update
   

2. install docker engine

   sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
   

3. verify installation

   sudo docker run hello-world
   

start container

Warning

for docker compose the command must be executed where compose.yaml is unlike docker run

navigate to dir where compose.yml is

docker compose up -d 

Note

-d stands for detached, means is will be running in backround. if u want to run it in the console and see the output, remove -d. to exit use Ctrl+C and will stop the container immediatly!

if u want to start specific container, use

docker compose up -d <CONTAINER>

stop container

to stop all container execute following command

docker compose down

if u want to stop specific container, use

docker compose down <CONTAINER>

update container

docker compose pull
docker compose up -d

clean system

docker image prune -af

docker system prune -af

remove all unused containers, networks, images (both dangling and unreferenced), and optionally, volumes

docker system prune -a --volumes --force 

use random yaml filename

docker compose -f <compose-dev.yml> up -d
docker compose -f <compose-dev.yml> down
etc

compose template

no need for versioning anymore bc obsolet

version: '3.8'

template

services:
    <SERVICENAME>:
        image: <IMAGE>:latest
        container_name: <CONTAINERNAME>
        restart: # unless-stopped # always # 
        labels:
            - "com.centurylinklabs.watchtower.enable=true"
        hostname: container-name.internal 
        user: 1000:1000
        networks:
            - <NETWORK>
        env_file:
            - .env
        depends_on: (1)
            - <SERVICENAME>
        volumes:
            - ./opt/application/data:/data 
            - data:/data
            - /media:/downloads
        ports:
            - "27015:27015/tcp"
            - "27015:27015/udp"
            - 1337:1337 # no definition means its tcp
            - 1337:1337/udp    
        cap_add:
            - NET_ADMIN
            - SYS_MODULE
        sysctls:
            - net.ipv4.conf.all.src_valid_mark=1 #
            - net.ipv6.conf.all.disable_ipv6=1 #  
        environment:
            <ENV>: /foo/bar
            <ENV>: "foo"
            <ENV>: 'foo'
            - <ENV>
            - <ENV>=foo
            - <ENV>="foo"
            - <ENV>='foo'
        network_mode: service:<serivcename> # to route through other container and use their ports under ports:
        network_mode: host
        deploy: 
            resources:
                limits:
                    cpus: '3.5'
                    memory: 50M
        stdin_open: true # Add local console for docker attach, docker attach --sig-proxy=false <SERVICENAME>
        tty: true # Add local console for docker attach

volumes:
    <VOLUME>:
        name: <NAME>
    <VOLUME>
        external: true
    <VOLUME>
networks:
    <NETWORK>:
        external: true
    <NETWORK>

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Admonition with annotations

!!! note annotate "Phasellus posuere in sem ut cursus (1)"

    Lorem ipsum dolor sit amet, (2) consectetur adipiscing elit. Nulla et
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    purus auctor massa, nec semper lorem quam in massa.

1.  :man_raising_hand: I'm an annotation!
2.  :woman_raising_hand: I'm an annotation as well!

getting logs

docker logs -f <container>
docker logs -f <container>
docker logs --follow <container>
docker logs --follow --until=3s <container>
docker logs --follow --until=30m <container>
docker logs --tail 100 <container>
docker compose <command> <server>

Tip

when using compose then possible without container_name and with servicename

checking open ports of other container in same network

docker exec -it <CONTAINER> /bin/sh
curl -v <CONTAINER>:<PORT>

if curl package doesn't exist

alpine

apk add curl

use random yaml filename

docker compose -f <compose-linkwarden.yml> up -d

to get variable of environment

docker exec <CONTAINER> env

jump into container terminal

there are different ways

docker exec -it <CONTAINER> /bin/sh

docker exec -it <CONTAINER> /bin/bash

docker exec -it <CONTAINER> sh

force restart of docker engine itself

If container cant be shut down

sudo systemctl restart docker.socket docker.service

location of docker volumes

/var/lib/docker/volumes/...