Step 1 of 4: Docker Basics

Goal

In this step, you will find and exercise a few basic Docker commands on your XNAT Vagrant VM.

Verify your setup

These instructions assume usage of the Docker server installed by default on the XNAT Vagrant VM. To access the server, setup (if necessary) and login to your Day 3 Practical Vagrant VM.

xnat-workshop-vms$ ./run xnat-31 setup
xnat-workshop-vms$ ./run xnat-31 ssh

This puts you at the console to your XNAT Vagrant VM, which includes an instance of Docker.

Verify Docker installation and functionality:

xnat@xnat-31:~$ docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 1.11.0
Storage Driver: aufs
 Root Dir: /var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 0
 Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: host bridge null
Kernel Version: 4.2.0-27-generic
Operating System: Ubuntu 14.04.4 LTS
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 1.954 GiB
Name: xnat-31
ID: 3XVY:66LA:O7YA:ZRXD:5O3L:HR56:FBKD:5CG3:HAV3:JDG7:K3MX:44G7
Docker Root Dir: /var/lib/docker
Debug mode (client): false
Debug mode (server): false
Registry: https://index.docker.io/v1/

If you see the above output, then your XNAT VM is set up correctly.

Command reference

Here are some commonly used commands, or ones that can give you more information. You don't have to do them now, but you may want to return to this page for reference later if you don't remember how to do something.

docker help

You can learn more about what commands you can give docker using the built-in Docker help documentation.

xnat@xnat-31:~$ docker help

docker help can also tell you more about each specific command.

xnat@xnat-31:~$ docker help <command>

docker images

xnat@xnat-31:~$ docker images

This lists all the images installed on the local docker server (you will have none right now).

docker ps

xnat@xnat-31:~$ docker ps

This lists the running containers on your docker server. Again, you will have none right now. If you want to see all containers—including ones that haven't started running or have already finished—you can include the -a flag.

xnat@xnat-31:~$ docker ps -a

docker pull

Download an image from a registry (defaults to https://hub.docker.com):

xnat@xnat-31:~$ docker pull <image_name>[:<tag_name>]

docker run

Create a new container from an image and run a command in that container:

xnat@xnat-31:~$ docker run [options] <image_name> [command]

Docker documentation

If you need more information about any of the docker commands, you can look through their command-line documentation. All the sub-commands have their own pages with explanations and examples.

Next step: Docker images