What is Docker? An Introduction to Docker Containers


23rd February 2023


6 min


Antony Towle

What is Docker? An Introduction to Docker Containers

Docker is an open-source project used to package applications into containers. The containers include everything the application needs to run in different environments. Due to this‚ Docker’s popularity has soared over the last decade‚ with millions of installs and active users.

Fundamentally‚ Docker enables the straightforward building‚ testing and deployment of applications‚ and allows scaling into any environment. This brings many advantages and various use cases.

In this blog‚ we’ll explore the following:

  • What Docker is and the problems it solves
  • How Docker uses containers
  • The pros and cons of using Docker
  • The tools to install to start using Docker.

What is Docker?

Docker is an open-source platform that uses containers to automate application deployment. The containers contain everything needed to run the applications they hold‚ able to deploy on-premises or in the cloud. As such‚ they make many aspects of development much easier‚ faster‚ and more collaborative.

Supported by Linux and Windows‚ Docker also makes it easy to manage and scale applications. It’s a popular choice for developers looking for an efficient solution for application deployment without having to install additional functionalities or use virtual machines.

The history of Docker

Docker’s origin story lies with Solomon Hykes‚ founder and creator of the Docker initiative. Hykes worked on the early stages of what would become Docker between 2010-2013‚ aiming to simplify application development and deployment using containers. Docker was then released as an open-source project in 2013.

Since then‚ Docker’s container-based approach has exploded in popularity. Based on Linux containers‚ Docker quickly became well-known among developers and system administrators for its ease of use. In recent years‚ Docker has become one of the most popular DevOps tools‚ raising over $100m in funding in 2022 to develop the platform further.

What is a Docker container?

Docker allows developers to build‚ run‚ test‚ and deploy distributed applications using containers. These containers bundle the application and any of its dependencies‚ meaning it can then run on other machines without installing further tools or configuration files. Overall‚ this creates a much more efficient and portable workflow for developers.

Each Docker container is isolated from others. It bundles the application’s necessary tools‚ libraries‚ and configuration files‚ able to run on any machine with Docker Engine installed. Each container also works on a single operating system kernel — making it much more lightweight than a virtual machine that must also load an operating system.

Isolating Docker containers makes it easier for developers to work on one application independently‚ without interference from other sources. It also improves security‚ isolating each application from the rest of the operating system.

Developers can create Docker containers using images‚ a convenient template that has everything needed to quickly deploy new containers.

Why use Docker?

So‚ what exactly are the benefits of using Docker?

  • Flexible: Docker containers bring a huge amount of portability and flexibility. They include everything needed to run the application on many devices or operating systems‚ without requiring the recipient to install any further files.
  • Lightweight: Docker containers are also fairly lightweight to run‚ especially when compared with virtual machines. For example‚ many containers can run on a single host system without creating copies of an operating system. This helps save vital time and computing resources.
  • Part of a large community. With Docker‚ developers can lean on a huge community and ecosystem of established tools. This makes it much easier to problem-solve and create new applications using proven methods.
  • Secure: A huge benefit of using Docker is that storing applications in containers brings security advantages. Developers run containers isolated from other applications‚ shielding them from any potential vulnerabilities they might bring. It also makes Docker applications much more difficult to attack.
  • Self-contained: Likewise‚ as each container includes any file systems‚ libraries or configuration files needed to run‚ it is isolated from other applications and cannot interfere with them.

Are there any downsides?

While using Docker brings many benefits‚ there are potential disadvantages. For example‚ while Docker containers are self-contained‚ they still use the host operating system resources. Virtual machines come with a larger size and resource overhead but virtualise their own guest operating system‚ fully isolating them from the host. This can be both a benefit and a downside‚ depending on your application’s speed‚ capability and security needs.

There are also a few aspects of Docker that can make it challenging to use‚ especially at first. Docker was designed for command-line usage‚ not necessarily graphical interfaces. It can also be tricky to manage and maintain a large number of Docker containers. Thankfully‚ there is an established community with tutorials to help.

How can you use Docker?

To run a Docker container‚ you’ll need to install Docker Engine on a host resource. Docker Engine includes various APIs that let applications communicate with the Docker daemon to run.

Downloading Docker gives you several tools and files‚ like Dockerfile‚ Docker Hub‚ and Docker Compose. Dockerfile helps build a Docker image with instructions on creating the container‚ while you can use Docker Hub to find and download many different types of container images. Once installed‚ you can begin by getting a Docker container image that matches your application needs.

Docker Compose uses YAML files to create and run Docker applications‚ enabling you to create‚ start and stop your containers. It also lets you view the status and log output of all running services. Docker Compose is a very popular way to work with containers — especially if you’re planning to use multi-container applications.

How can hedgehog lab help?

Docker is an efficient and effective tool for automating the deployment of applications. Popular among application developers‚ Docker enables the packaging of code and dependencies into a standardised unit that can be deployed on any server. If you need to share an application or deploy it in a different environment‚ using Docker containers allows you to bundle everything it needs to work efficiently and quickly.

At hedgehog lab‚ we use Docker to help us build scalable and resilient Laravel platforms and web applications. Get in touch with hedgehog lab to learn more about your application development options. You can also check our resource library for more technology news and insights.