# Docker Tutorial
[TOC]
## Reference
[基本操作](https://ithelp.ithome.com.tw/articles/10186431)
## Install Docker
1. Update package list

sudo apt-get update

2. Install docker

sudo apt-get install docker.io

3. Add user to the docker group

sudo usermod -aG docker ${USER}

4. Logout and log back to take effect
## Build Image

The below example will take Ubuntu20.04 install ROS for example

1. Create Dockerfile

touch Dockerfile

2. Open Dockerfile and write

# We want to use ubuntu:20.04 for base image
FROM ubuntu:20.04
# install prequsites package
RUN apt-get update && \
    apt-get install -y curl gnupg2 lsb-release && \
    curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | apt-key add - && \
    echo "deb http://packages.ros.org/ros2/ubuntu focal main" > /etc/apt/sources.list.d/ros2-latest.list && \
    apt-get update && \
    apt-get install -y ros-foxy-desktop
# we can also use RUN + command we want to use
RUN git clone https://github.com/ika-rwth-aachen/mqtt_client.git
# Change directory
WORKDIR /root/catkin_ws/src/mqtt_client
RUN rosdep install -r -y --ignore-src --from-paths .
WORKDIR /root/catkin_ws

# Add additional user if you want
## create a non-root user
ARG USER_ID=1000
RUN useradd -m --no-log-init --system  --uid ${USER_ID} ncrl -g sudo
RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers
USER ncrl
WORKDIR /home/ncrl

3. Build your docker image

docker build -t my-ros-image .

## Run Container
1. use a bash script to run your docker container with serveral option

#!/usr/bin/env bash
xhost +local: 
# allow display GUI
    docker run \ 
    # run docker
    -it \ 
    # enable TTY terminal
    --env="DISPLAY" \
    --env="QT_X11_NO_MITSHM=1" \
    --volume="/tmp/.X11-unix:/tmp/.X11-unix:rw" \ # allow GUI
    -p 2233:22 \
    --rm \ 
    # Automatically remove container when it is stopped
    --name ncrl_mqtt \ 
    # Docker name is "ncrl_mqtt".
    --user root \ 
    # Runs the container as the root user.
    --network host \ 
    # Access network services running on the host system.
    -e GRANT_SUDO=yes \
    -v ~/ncrl_mqtt:/root/catkin_ws \  
    #This option mounts the directory ~/ncrl_mqtt 
    #on the host system to the directory 
    #/root/catkin_ws inside the Docker container.
    #This allows the user to share files between 
    #the host system and the Docker container.
    leeandy90833/ncrl:ncrl_mqtt \
    # This specifies the Docker image to use, 
    # leeandy90833/ncrl:ncrl_mqtt.
    bash

## Publish Image
[reference](https://docs.docker.com/engine/reference/commandline/push/)
1. Tag the image with a name that includes the registry URL and the image name:

#docker tag IMAGE_NAME REGISTRY_URL/IMAGE_NAME:TAG
docker tag my-image docker.io/my-username/my-image:latest

2. Login to Docker registry

docker login REGISTRY_URL

3. Push the image