This is an individual exercise
This primer contains 3 exercises. Each is worth 0.5% of your course mark.
In this course, you must use Docker. To make sure you have everything set up and can run docker comfortably, you will need to complete these short exercise and show your tutor by the end of your Week 3 lab to gain marks.
You can download docker at the following https://docs.docker.com/get-docker/ Once you download and install it, open it and ensure it is running whenever you are developing your code.
Clone this repo (if you don't know how to do this, refer to the Git primer which you are also required to complete by Week 3 lab time)
There are three short exercises.
Exercise 1 - Basic exercise to make sure you have installed Docker and everything runs perfectly. You will not need to write any code for this exercise.
Exercise 2 - Writing Dockerfiles.
Exercise 3 - Writing Docker compose files.
There are lots of comments throughout this repo. If you're stuck, read through the code and try to understand what's going on! Make sure to reuse the code from exercise 1 when doing exercise 2 and similarly with exercise 3.
Note that building each container can take several minutes. This is completely normal. Please ensure you have completed these early so that if you have issues, we have time to help you on Ed forum or in your Week 1-2 labs.
Our goal with creating a Docker container is to bundle up all dependencies required to run an application along with the application itself. This means that you can specify all instructions needed to run your application, any depedencies it needs (e.g. Python3.11, Flask library etc) and run it on any device that has Docker installed regardless of the OS or the dependencies being present on that laptop.
To get our container, we need to create a Docker image which is a set of instructions to run our container. This first involves creating a Dockerfile which defines the instructions for setting up the application environment. Then you can turn this into an image and run the container using docker run. Detailed instructions for how to structure your Dockerfile can be found in each of the Dockerfiles in this repo.
The application we made in this repo is much more complicated - it contains a frontend and a backend which are each their own containers. We can use docker-compose.yml to specify exactly what services we want to run to make this application function. Each of these services must either have a pre-built image or you must have a Dockerfile for it. In the case of this repo, you can see that the frontend and backend each have their own Dockerfile that specifies exactly what is needed for each container. Then, if you look back to docker-compose.yml you can see that we define the services we want, any environment variables, whether we want to map any internal ports to external ports etc. You can find a full list of things you can specify online.
After we create this file, we can use docker-compose up which will install any new dependencies (it may take a while the first time you run it) and then run the application.
- https://docker-curriculum.com/ is an amazing tutorial on Docker. If you want to go into a little more depth, read through it and complete the exercises in it!
- https://www.freecodecamp.org/news/the-docker-handbook/ is a much more in-depth resource on Docker. It provides a really detailed guide to most key features but is well beyond the scope of these exercises.