Docker has become an essential tool for developers and system administrators to build, ship, and run distributed applications. With Docker, you can easily pack, ship, and run any application as a lightweight container, which is great for continuous development, integration, and deployment workflows.
There are a few ways to install Docker on Linux systems, including using automated scripts, repositories, or snaps. In this guide, we will focus on installing Docker using the snap package manager on Ubuntu and other Linux distributions that support snaps.
What is Docker?
Docker is an open platform for developing, shipping, and running applications. Docker enables you to separate your applications from your infrastructure so you can deliver software quickly. With Docker, you can manage your infrastructure in the same ways you manage your applications.
Some key features and benefits of Docker include:
- Lightweight virtualization – Docker containers share the host system’s kernel and run as isolated processes for faster startup times.
- Portability – You can build locally, deploy to the cloud, and run anywhere.
- Version control and component reuse – Common components can be reused across multiple applications.
- Application isolation – Docker reduces conflicts between components and applications.
- Speed and efficiency – Containers start almost instantly and have smaller file sizes than VMs.
- Developer productivity – Docker enables faster coding with quick rebuild and testing of containerized applications.
With Docker, developers can focus more on writing code rather than managing infrastructure. Operations teams can deploy and scale applications faster and more securely. Overall, Docker improves the development lifecycle by allowing faster shipping of applications.
What are Docker containers?
Docker containers are lightweight, stand-alone executable packages that include everything an application needs to run including the code, runtime environment, system tools, libraries, and settings. Containers share the host machine’s OS system kernel and therefore do not require an OS per application, reducing redundancy and overhead.
Containers are created from Docker images. Docker images are read-only templates that specify what is included inside the container. Images are composed from layered filesystems stacked on top of each other. This allows images to share common files and reuse components from other images, making them very lightweight and fast.
Some key advantages of Docker containers:
- Standardized packaging – Applications are neatly packaged with dependencies and settings for reliable deployment.
- Lightweight – Containers share OS system resources resulting in faster startup times.
- Portable – You can build locally, deploy to the cloud, and run anywhere.
- Scalable – You can increase or scale back instances as needed.
- Secure – Applications are isolated in containers limiting access to the host system.
In summary, containers provide a logical packaging mechanism in which applications can be abstracted from the environment and assure that they work uniformly when moved between different environments.
Overview of snap package manager
Snap is a package management system developed by Canonical for the Linux operating system. With snap, applications are packaged with their dependencies to run on a variety of Linux distributions while being isolated from the host OS.
Some key features of snap packages include:
- Works across Linux distributions – Snaps work on any Linux distro with snap support.
- Automatic updates – Applications stay updated automatically with each release.
- Easy rollback – Easily roll back to previous versions in case of issues.
- Security – Each snap runs isolated with restricted system access.
- Composability – Snaps work together through content interface connections.
Snaps are discoverable and installable from the Snap Store. Popular applications packaged as snaps include Spotify, Slack, Skype, Telegram, etc. Snaps are the recommended way to install Docker on Linux.
Advantages of using snaps for Docker
There are several advantages to using snaps over other methods to install Docker:
- Automatic updates – Docker snap will update automatically in the background when new versions are released.
- Isolation – Docker snaps run isolated with restricted system access for improved security.
- Works across distributions – Docker snap works on any Linux distro with snap support regardless of native package versions.
- Dependency management – Docker snap includes required libraries and dependencies out-of-the-box.
- Easy install – Docker can be installed easily with a simple snap install command.
- Rollback – If issues arise, snaps make it easy to roll back to a previous working version.
Overall, using snaps streamlines installing, running, managing, and updating Docker on Linux. Snap packages help ensure Docker will work uniformly across distributions with minimal compatibility issues.
Requirements for installing Docker snap
Installing Docker using the snap package has the following requirements:
- Linux distribution with snap support (most major distros)
- Snap package manager installed
- Internet connection (for downloading Docker snap)
- Root privileges or sudo access
You will also need to decide if you want to install the Docker stable snap or edge snap:
- Stable – Recommended for most users. Gets bug fixes and security updates but lags a bit behind the latest Docker release.
- Edge – Gets the latest Docker features first. Less tested but allows earlier access to new Docker versions.
Check if your Linux distro meets the requirements for Docker snap install. Then decide whether to use the edge or stable snap based on your needs.
Installing snap on Linux
Before installing Docker as a snap package, you must first ensure the snap package manager is installed on your Linux distribution. Here is how to install snap:
Ubuntu / Debian
Snap comes pre-installed on recent Ubuntu and Debian releases. To confirm, check if snap is already installed:
snap --version
If not installed, update apt repositories and install snap:
sudo apt update
sudo apt install snapd
Fedora
Install the snapd service:
sudo dnf install snapd
Enable the snapd socket:
sudo systemctl enable --now snapd.socket
Arch Linux
Install the snapd package:
sudo pacman -S snapd
Enable the systemd units:
sudo systemctl enable --now snapd.socket
Other Linux distros
Use the distribution’s package manager to install snapd. Then enable and start associated services.
Once snap is installed, continue to install Docker snap package.
Installing Docker snap
With snap installed, you can now easily install Docker using the snap command. Here is how to install the stable Docker snap:
sudo snap install docker
To get the edge version instead:
sudo snap install docker --edge
The Docker snap will now install and automatically start the Docker service. Verify it is working:
docker version
If it displays Docker version info, Docker snap install succeeded!
Managing Docker snap
Here are some common commands for managing your Docker snap install:
# Start Docker service
sudo snap start docker
# Stop Docker service
sudo snap stop docker
# Restart Docker service
sudo snap restart docker
# List installed snaps
snap list
# Update Docker snap
sudo snap refresh docker
# Switch from edge to stable
sudo snap refresh docker --stable
# Uninstall
sudo snap remove docker
The Docker snap will update automatically when new edge or stable versions are released by default. Update scheduling can be configured as well.
Using Docker snap
With Docker installed through snap, you can now use Docker like normal:
# Pull an image
docker pull ubuntu
# Run container
docker run -it ubuntu bash
# List containers
docker ps
# Build images
docker build .
The Docker snap integrates seamlessly. Just prefix Docker commands with sudo since it installs to root by default.
Customizing Docker snap
There are a few ways to customize Docker installed via snap:
- Install stable instead of edge snap or switch between them
- Change auto-update schedule (or disable auto-updates)
- Mount host directories into containers
- Adjust amount of resources allocated to containers
For example, to mount a host directory:
sudo snap set docker daemon.json='{"data-root": "/home/user/docker"}'
sudo systemctl restart snap.docker.dockerd
And to limit container CPU usage:
sudo snap set docker daemon.json='{"default-runtime": "nvidia", "default-cpus": 1}'
sudo systemctl restart snap.docker.dockerd
Refer to Docker and snap documentation for more customization options. Overall, Docker snap provides a scalable method to install, run, manage, and update Docker on Linux.
Conclusion
Installing Docker via snap provides an efficient way to get Docker running on Linux. Key benefits include automatic updates, dependency management, isolation, and portability across distributions. Simply install snap, install the Docker snap package, and start using Docker to build and deploy your applications.
Snaps make it easier to keep Docker updated across all your Linux machines. No need to manually update Docker or install dependencies. Just use the snap refresh command or let snap handle updates automatically. This helps improve security and access to the latest Docker releases.
Overall, Docker snap simplifies installing and running Docker in production, test, and development environments. The ubiquitous availability of Docker snap packages lowers the barrier for adoption across various Linux distributions. Just snap install Docker and unlock the advantages of containers today.