Learning Docker - Part 2 - Docker cheatsheet

| Categories: Tutorials

Config to run docker without sudo

By default, docker needs to be run with root privilege, but we don’t want that for various reasons. Follow these steps to allow running docker without sudo:

  1. Add a group named docker:

     sudo groupadd docker

  2. Add the user you want to run docker without sudo to group docker

     sudo usermod -aG docker ${USER}

  3. Restart docker daemon:

     sudo service docker restart

  4. Relogin, or running the following command:

     newgrp docker

Note: This allows running docker without using the sudo command. However, files created by docker by default are still owned by root. To truly avoid giving root privilege to docker, specify option -u <user id> when running docker run. For example:

docker run -u `id -u $USER` <image>

Or

docker run -u $UID <image>

If you are using docker-compose, then you should specify the option user in your docker-compose.yml file. For example:

version: '3'
services:
  jekyll:
    user: $UID
    image: btquanto/docker-jekyll
    ports:
      - 4000:4000
    volumes:
      - ./:/src
    command: jekyll serve -H 0.0.0.0 --draft

Basic docker commands

  1. List all images:

     docker images

  2. List all running containers:

     docker ps

    List all containers:

     docker ps -a

  3. Create and run a new container:

     docker run <image name>

    Create a new container, and give the container a name

     docker run --name <container name> <image name>

    Create a new container under interactive mode, and run bash

     docker run -ti <image name> /bin/bash

    Create a new container in detached mode

     docker run -d <image name>

    Run docker container under a different user (for security)

     docker run -u `id -u <username>` <image name>

    Run docker container under current user

     docker run -u $UID <image name>

    Well, you can combine these together, for example:

     docker run -u $UID -dti --name ubuntu1604 ubuntu:16.04 /bin/bash

  4. Attach to a container:

     docker attach <container id/ name>

  5. Detach from a container:

     <Ctrl> + P,Q

  6. Start a container:

     docker start <container id/ name>

    Start and attach to a container

     docker start -a <container id/ name>

  7. Stop a container:

     docker stop <container id/ name>

  8. Remove a container:

     docker rm <container id/ name>

  9. Remove an image:

     docker rmi <image name>

  10. Create an image from a container:

    docker commit <container id/ name> <new image name>