Introducing Docker

Docker is a relatively hassle-free, extensive and open source containerisation platform. The Docker ecosystem allows applications (images - we’ll come onto this in a later room) to be deployed, managed and shared with ease.

Working on Linux, Windows and MacOS, Docker is a smart choice for running applications. Applications can be published as “images” and shared with others. All that is required is pulling (downloading) the image and running it with Docker.

Docker employs the same technology used in containerisation to isolate applications into containers called the Docker Engine. The Docker Engine is essentially an API that runs on the host operating system, which communicates between the operating system and containers to access the system’s hardware (such as CPU, RAM, networking and disk)

Because of this, the Docker engine is extensive and allows you to do things like:

1. Connect containers together (for example, a container running a web application and another container running a database)

2. Export and import applications (images)

3. Transfer files between the operating system and container

Docker uses the programming syntax YAML to allow developers to instruct how a container should be built and what is run. This is a significant reason why Docker is so portable and easy to debug; share the instructions, and it will build and run the same on any device that supports the Docker Engine.

The Docker engine allows containers to be orchestrated, meaning that multiple containers can be built as part of a group, allowing containers to communicate with each other (for example, one container running a web server and another container running a database can communicate). We will come onto this feature in a later room.