Docker¶

installation¶

MacOS¶

brew install --cask docker

or

https://docs.docker.com/desktop/install/mac-install/

Ubuntu¶

official doc: https://docs.docker.com/engine/install/ubuntu/#install-using-the-repository

update apt and install necessary packages

sudo apt-get update
sudo apt-get install -y ca-certificates curl gnupg lsb-release

add Docker’s official GPG key

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

set up the stable repository

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

install docker engine

sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io

test if is installed correctly

sudo docker run hello-world

will download the image hello-world and pring some messages
sudo docker ps -a to check if it's running

Arch¶

install

sudo pacman -S docker

start

sudo systemctl start docker

image types¶

https://medium.com/swlh/62171ed4531d

slim: smaller image
alpine: even smaller image

init¶

make docker start on boot¶

sudo systemctl enable docker.service
sudo systemctl enable containerd.service

https://docs.docker.com/engine/install/linux-postinstall/#configure-docker-to-start-on-boot

start docker¶

sudo service docker start

or

sudo systemctl start docker

show running containers¶

docker ps

go into a docker container¶

docker exec -it <container_name> /bin/bash

or

docker exec -it <container_name> /bin/sh

https://github.com/docker/for-linux/issues/246#issuecomment-455010125

stop a docker container¶

docker stop <container_id>

remove a docker container¶

docker rm -f <container_id>

container log¶

docker logs <container_id>

Run a container - docker run¶

docker run <flags> <image>

Run a docker container from an image¶

docker run --name <container_name> -d --rm <image_name/id>
# if it exits immediately, try
docker run --name <container_name> -dit --rm <image_name/id>

--rm for auto remove when a container with the same name already exist (but only when it is also created with the --rm flag)

https://stackoverflow.com/a/31143261/15493213

with port forwarding

-p <port>:<port>

with webcam

--device=/dev/video0:/dev/video0

container resource control¶

assign to specific cpu(s)
- --cpuset-cpus <#cpu>
- e.g.
  - --cpuset-cpus 1
  - --cpuset-cpus 1,3
limit cpu usage
- --cpus <max # of cpu>
- e.g.
  - --cpus 0.5
check the cpu related config of a container
- docker inspect <container> | grep -i cpu
- set 1 cpus -> 10^9 NanoCpus

ref

Store images on cloud repo¶

Docker Hub
Harbor

Show all docker images¶

docker images

remove a docker image¶

docker image rm -f <image_id>

build a docker image¶

build a docker image following the Dockerfile in the directory

docker build -t <name> .

rebuild

docker build --no-cache -t <name> .

push image to dockerhub¶

Login to dockerhub if you haven't

docker login

Tag the image

docker tag <image_name> <username>/<repo>:<tag>

Push the image

docker push <username>/<repo>:<tag>

docker-compose¶

will use docker-compose.yml

build & start containers¶

docker-compose up -d --build

build containers¶

docker-compose build

start containers¶

docker-compose up -d

stop containers¶

docker-compose stop

device¶

use your webcam in docker container¶

with docker run

add --device=/dev/video0:/dev/video0 when doing docker run

with docker-compose

add this to your service in docker-compose.yml

        devices:
            - /dev/video0:/dev/video0

Dockerize a flask app¶

# syntax=docker/dockerfile:1
FROM python:3.8-slim-buster
WORKDIR /dir_name
ADD . /dir_name
RUN pip3 install -r requirements.txt
CMD python3 application.py

remove unused things¶

docker images & containers are stored in /var/lib/docker/

remove: - all stopped containers - all networks not used by at least one container - all dangling images - all dangling build cache

docker system prune

remove all images without at least one container associated to them

docker image prune --all

https://stackoverflow.com/questions/46672001/

Troubleshooting¶

---> [Warning] IPv4 forwarding is disabled. Networking will not work.¶

restard docker

sudo systemctl restart docker

https://stackoverflow.com/a/59135923/15493213

express app work when run direclty but not with docker¶

try listening on host 0.0.0.0 instead of localhost

python cv2 ImportError: libGL.so.1: cannot open shared object file: No such file or directory¶

Use opencv-python-headless instead of opencv-python

https://stackoverflow.com/a/69655111/15493213

python app doesn't print things¶

Use python3 -u <python-file> instead of python3 <python-file>. If still nothing, add the PYTHONUNBUFFERED variable.