And How is it Useful?
As I work on more and more assignments I am constantly hit with the same error while starting up my work for class:
The fix to this is very simple; Start up Docker. This error simply means that my VS Code is attempting to open a container, but I don’t have Docker running to do that. As this reminder started to get me in the habit of making sure Docker was open before attempting to work in a container, I started to ask myself, “What is Docker actually doing and what is a container?”.
I found an excellent post that breaks down what Docker is and how each of the individual parts of Docker work together. The blog, “Introduction to Containers and Docker” by Liam Mooney (https://endjin.com/blog/2022/01/introduction-to-containers-and-docker) provides great information of how Docker used containers with an example of a dockerfile and how to build your own container. Mooney starts off with explaining what a container is and how they vary from virtual machines. Containers and virtual machines are both ways of creating an isolated environment on a computer, however, virtual machines are bulky and slow in comparison to containers. This means they can both be used to create stable environments to run software in, however, virtual machines require an image of an OS to be installed on a host computer. This OS also needs to be installed every time you start the virtual machine. This paired with taking up a lot of space and CPU resources by having two OS’s that share a lot of features leads to much longer start up times and slower runtime. Containers use the capabilities and features of the host OS to run the environments. This makes them much lighter, only needing select software and dependencies to be included in the environment.
This blog goes on to explain how Docker is able to use containers to create environments in seconds. Docker uses dockfiles, which are a list of commands the docker daemon will execute to build the image you wish to run for your environment. Docker daemon is a background service that builds, manages, and runs the environment by being the middleman between the container and the host OS. Once the image has been built, it can be opened in any number of containers that are all independent of each other.
The examples given by Mooney are great for understanding exactly how you would create a simple container. Giving me a better look at what Docker is actually doing when I am working in VS code and its opening containers for me to work in. Although I don’t see myself designing my own containers anytime soon, it is great to know how the software is executing and managing these environments.
CS Learning 