Docker is based on the concept of building images which contain the necessary software and configuration for applications. We can also build distributable images that contain pre-configured software like an Apache server, Caching server, MySQL server, etc. We can share our final image on the Docker HUB to make it accessible to everyone.
First we need to install docker on our local machine. Steps to install docker for ubuntu
- Docker requires a 64-bit installation regardless of your Ubuntu version.
- Your kernel must be 3.10 at minimum. The latest 3.10 minor version or a newer maintained version are also acceptable.
To check your current kernel version, open a terminal and use
uname -r to display your kernel version:
$ uname -r
Update your apt sources
APT repository contains Docker 1.7.1 and higher. To set
APT to use packages from the new repository:
- Log into your machine as a user with
- Open a terminal window.
- Update package information, ensure that APT works with the
httpsmethod, and that CA certificates are installed.
$ sudo apt-get update $ sudo apt-get install apt-transport-https ca-certificates
- Add the new
$ sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
- Open the
/etc/apt/sources.list.d/docker.listfile in your favorite editor.If the file doesn’t exist, create it.
- Remove any existing entries.
- Add an entry for your Ubuntu operating system
- On Ubuntu Trusty 14.04 (LTS)
deb https://apt.dockerproject.org/repo ubuntu-trusty main
- Save and close the
- Update the
$ sudo apt-get update
For Ubuntu Trusty, Wily, and Xenial, it’s recommended to install the
linux-image-extra kernel package. The
linux-image-extra package allows you use the
aufs storage driver.
Install both the required and optional packages.
$ sudo apt-get install linux-image-generic-lts-trusty
Log into your Ubuntu installation as a user with
- Update your
$ sudo apt-get update
- Install Docker.
$ sudo apt-get install docker-engine
- Start the
$ sudo service docker start
dockeris installed correctly.
$ sudo docker run hello-world
This command downloads a test image and runs it in a container. When the container runs, it prints an informational message. If it runs successfully then docker is installed.
Docker images are the basis of containers. An image can be considered a class definition. We define its properties and behavior. To browse the available images, we can visit the Docker HUB and run
docker pull <image> to download them to the host machine.
Listing images on the host
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu 14.04 1d073211c498 3 days ago 187.9 MB
busybox latest 2c5ac3f849df 5 days ago 1.113 MB
training/webapp latest 54bb4e8718e8 5 months ago 348.7 MB
Working with Dockerfile
Dockerfile in your PHP project. This is the docker file for engelsystem.
Our Dockerfile is now complete and ready to be built:
Building the Image
docker build . command will build the
Dockerfile inside the current directory:
Our image is now labeled and tagged. The final step is to push it to the Docker HUB. This step is optional, but it’s still useful if we’re planning on sharing the image and and helping others with their development environment.