What is Docker?
Docker is an application that makes it simple and easy to run application processes in a container, which are like virtual machines, only more portable, more resource-friendly, and more dependent on the host operating system. For a detailed introduction to the different components of a Docker container, check out The Docker Ecosystem: An Introduction to Common Components. There are two methods for installing Docker on Ubuntu 16.04. One method involves installing it on an existing installation of the operating system. The other involves spinning up a dedicated server with a tool called Docker Machine that auto-installs Docker on it. In this tutorial, you'll learn how to install docker and use it on an existing installation of Ubuntu 16.04.
How to install docker
Before install Docker, it should required updated packages. To update the packages, use the following command
$ sudo apt-get update
Use the following command to add the GPG key for the official Docker repository to the system
$ sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
The sample output should be like this
Executing: /tmp/tmp.akuLSrhQz8/gpg.1.sh --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D gpg: requesting key 2C52609D from hkp server p80.pool.sks-keyservers.net gpg: key 2C52609D: public key "Docker Release Tool (releasedocker) <docker@docker.com>" imported gpg: Total number processed: 1 gpg: imported: 1 (RSA: 1)
To add the Docker repository to APT sources, use the following command
$ echo "deb https://apt.dockerproject.org/repo ubuntu-xenial main" | sudo tee /etc/apt/sources.list.d/docker.list
To update the package database with the Docker packages from the newly added repository, use the following command
$ sudo apt-get update
Make sure you are about to install from the Docker repository instead of the default Ubuntu repository. To verify it, use the following command
$ apt-cache policy docker-engine
The sample output should be like this
docker-engine:
Installed: (none)
Candidate: 1.11.1-0~xenial
Version table:
1.11.1-0~xenial 500
500 https://apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
1.11.0-0~xenial 500
500 https://apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
Notice that, docker-engine is not installed,to install Docker-engine, use the following command
$ sudo apt-get install -y docker-engine
The sample output should be like this
Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: apport-hooks-elementary contractor libgda-5.0-4 libgda-5.0-common libgranite-common libgranite3 libgsignon-glib1 libindicate5 libnoise-core0 libtagc0 mysql-server-5.7 mysql-server-core-5.7 Use 'sudo apt autoremove' to remove them. The following additional packages will be installed: aufs-tools cgroupfs-mount The following NEW packages will be installed: aufs-tools cgroupfs-mount docker-engine 0 upgraded, 3 newly installed, 0 to remove and 212 not upgraded. Need to get 14.6 MB of archives. After this operation, 73.7 MB of additional disk space will be used. Get:1 http://in.archive.ubuntu.com/ubuntu xenial/universe amd64 aufs-tools amd64 1:3.2+20130722-1.1ubuntu1 [92.9 kB] ..............................................................................................
To check whether docker is started or not, use the following command
$ sudo systemctl status docker
The sample output should be like this
● docker.service - Docker Application Container Engine
Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: e
Active: active (running) since Mon 2016-05-23 10:36:08 IST; 5min ago
Docs: https://docs.docker.com
Main PID: 14186 (docker)
Tasks: 20 (limit: 512)
Memory: 21.5M
CPU: 385ms
CGroup: /system.slice/docker.service
├─14186 /usr/bin/docker daemon -H fd://
└─14204 docker-containerd -l /var/run/docker/libcontainerd/docker-con
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.169666150+05:30"
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.261017824+05:30"
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.469630404+05:30"
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.829495384+05:30"
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.830931516+05:30"
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.831009718+05:30"
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.831055091+05:30"
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.831113464+05:30"
May 23 10:36:08 linux systemd[1]: Started Docker Application Container Engine.
May 23 10:36:08 linux docker[14186]: time="2016-05-23T10:36:08.855330148+05:30
To start the Docker service, use the following command
$ sudo service docker start
To view all the available subcommands of Docker, use the following command
$ docker
The sample output should be like this
Usage: docker [OPTIONS] COMMAND [arg...]
docker daemon [ --help | ... ]
docker [ --help | -v | --version ]
A self-sufficient runtime for containers.
Options:
--config=~/.docker Location of client config files
-D, --debug Enable debug mode
-H, --host=[] Daemon socket(s) to connect to
-h, --help Print usage
-l, --log-level=info Set the logging level
--tls Use TLS; implied by --tlsverify
--tlscacert=~/.docker/ca.pem Trust certs signed only by this CA
--tlscert=~/.docker/cert.pem Path to TLS certificate file
--tlskey=~/.docker/key.pem Path to TLS key file
--tlsverify Use TLS and verify the remote
-v, --version Print version information and quit
Commands:
attach Attach to a running container
build Build an image from a Dockerfile
commit Create a new image from a container's changes
cp Copy files/folders between a container and the local filesystem
create Create a new container
diff Inspect changes on a container's filesystem
events Get real time events from the server
exec Run a command in a running container
export Export a container's filesystem as a tar archive
history Show the history of an image
images List images
import Import the contents from a tarball to create a filesystem image
info Display system-wide information
inspect Return low-level information on a container or image
kill Kill a running container
load Load an image from a tar archive or STDIN
login Log in to a Docker registry
logout Log out from a Docker registry
logs Fetch the logs of a container
network Manage Docker networks
pause Pause all processes within a container
port List port mappings or a specific mapping for the CONTAINER
ps List containers
pull Pull an image or a repository from a registry
push Push an image or a repository to a registry
rename Rename a container
restart Restart a container
rm Remove one or more containers
rmi Remove one or more images
run Run a command in a new container
save Save one or more images to a tar archive
search Search the Docker Hub for images
start Start one or more stopped containers
stats Display a live stream of container(s) resource usage statistics
stop Stop a running container
tag Tag an image into a repository
top Display the running processes of a container
unpause Unpause all processes within a container
update Update configuration of one or more containers
version Show the Docker version information
volume Manage Docker volumes
wait Block until a container stops, then print its exit code
You can search for images available on Docker Hub by using the docker command with the search subcommand.
$ sudo docker search ubuntu
The sample output should be like this
NAME DESCRIPTION STARS OFFICIAL AUTOMATED ubuntu Ubuntu is a Debian-based Linux operating s... 3953 [OK] ubuntu-upstart Upstart is an event-based replacement for ... 62 [OK] rastasheep/ubuntu-sshd Dockerized SSH service, built on top of of... 26 [OK] torusware/speedus-ubuntu Always updated official Ubuntu docker imag... 26 [OK] ubuntu-debootstrap debootstrap --variant=minbase --components... 24 [OK] nickistre/ubuntu-lamp LAMP server on Ubuntu 6 [OK] nickistre/ubuntu-lamp-wordpress LAMP on Ubuntu with wp-cli installed 5 [OK] nuagebec/ubuntu Simple always updated Ubuntu docker images... 4 [OK] nimmis/ubuntu This is a docker images different LTS vers... 4 [OK] maxexcloo/ubuntu Docker base image built on Ubuntu with Sup... 2 [OK] partlab/ubuntu Simple Ubuntu docker images. 1 [OK] darksheer/ubuntu Base Ubuntu Image -- Updated hourly 1 [OK] admiringworm/ubuntu Base ubuntu images based on the official u... 1 [OK] jordi/ubuntu Ubuntu Base Image 1 [OK] webhippie/ubuntu Docker images for ubuntu 0 [OK] teamrock/ubuntu TeamRock's Ubuntu image configured with AW... 0 [OK] esycat/ubuntu Ubuntu LTS 0 [OK] life360/ubuntu Ubuntu is a Debian-based Linux operating s... 0 [OK] widerplan/ubuntu Our basic Ubuntu images. 0 [OK] konstruktoid/ubuntu Ubuntu base image 0 [OK] lynxtp/ubuntu https://github.com/lynxtp/docker-ubuntu 0 [OK] datenbetrieb/ubuntu custom flavor of the official ubuntu base ... 0 [OK] ustclug/ubuntu ubuntu image for docker with USTC mirror 0 [OK] uvatbc/ubuntu Ubuntu images with unprivileged user 0 [OK] rallias/ubuntu Ubuntu with the needful 0 [OK]
To see the images that have been downloaded to your computer, use the following command
$ sudo docker images
The sample output should be like this
REPOSITORY TAG IMAGE ID CREATED SIZE hello-world latest 94df4f0ce8a4 3 weeks ago 967 B
To run the Docker container, use the following command
$ sudo docker run -it hello-world
Above command runs hello-word container. the sample output should be like this
Hello from Docker.
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker Hub account:
https://hub.docker.com
For more examples and ideas, visit:
https://docs.docker.com/engine/userguide/
To listing Docker Containers, use the following command
$ sudo docker ps
The sample output should be like this
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES f7c79cc556dd ubuntu "/bin/bash" 3 hours ago Up 3 hours silly_spence
After this article, you will be able to understand – How To Install and Use Docker on Ubuntu 16.04 we will come up with more Linux based tricks and tips. Keep reading!