Docker - Getting started

docker --version
docker info
docker run hello-world # run a new conatiner, in this case `hello-world`
docker ps
docker ps -a # see running (and stopped) containers
docker images # see info about images

# 1. Clone
git clone https://github.com/docker/getting-started.git

# 2. Build
cd getting-started
docker build -t docker101tutorial .

# 3. Run
docker run -d -p 80:80 --name docker-tutoial docker101tutorial

What's the difference between Docker and Docker Compose?

The gist is that docker manages individual containers while docker-compose manages multiple containers..

docker.io and docker-compose are separate packages.

Docker is the CLI managing individual containers while Docker Compose is a tool built on top of docker cli that can be used to manage multi-container applications.

With Docker Compose, you can define stacks in swarm mode. And you do lots of shell scripting as well.

Start docker automatically on boot

See if docker is added to start on system boot

systemctl list-units --type service | grep -i docker

If you don't get anything, enable it

sudo systemctl enable docker

https://docs.docker.com/engine/install/linux-postinstall/#configure-docker-to-start-on-boot https://askubuntu.com/questions/912216/16-04-command-to-list-all-services-started-on-boot

Restart docker containers with system restart

You need to specify a restart policy using the --restart flag.

docker run -d --restart unless-stopped foo

There are four policies

• no is default. doesn't restart any containers
• on-failure only restart container if the exit code indicates error instead of success.
• always will always restart all containers, even if you had manually stopped them
• unless-stopped will restart all containers, but not the ones you had manually stopped before

With Docker Compose, restart has been supported since version 2, and in version 3 you also get restart_policy but it only applies to swarms

version: '2'
services:
  web:
    image: apache
    restart: always

Links

• Overview of Docker Compose
• StackOverflow: What is the difference between docker and docker-compose
• Start containers automatically
• Ensuring Containers Are Always Running with Docker's Restart Policy
• StackOverflow: Docker-Compose Restart Policy
• Compose file reference: restart
• Compose file reference: RESTART_POLICY
• Configure Docker to start on boot