What is docker?
Docker is an installable application that will ensure that every application runs the same on the environment. This is most commonly used on major cloud providers to host databases and backend APIs. Docker uses a mock virtual environment to ensure that every instance or container running will run the same.
Docker Images
Docker Images are the build for your application. When you run the Image you get a container running which can be deactivated when you please. You can control a docker container's os along with using other popular Images. These things ensure to run the application the same and ensure the same functionality.
Using the Dockerfile
Having a .Dockerfile tells the editor how to read your virtual environment. Using a base Image can set up a lot of the configuration for you. Using the FROM command sets the Image
FROM python:3.6This example uses docker's official python image but you can run ubuntu or whatever else you please
Next you want to set your work directory, where you want to install dependencies.
WORKDIR /This will set the directory in the normal folder
After that you want to install your dependencies
COPY Pipfile Pipfile.lock ${PROJECT_DIR}/
RUN pipenv install --system --deployThe Copy Command tells docker which files you want to use in the next command. In this case we want to use Pipfile and Pipfile.lock but you can also want packages.json depending on the project
ENV DEBUG=FalseYou can also set environment variables in docker using ENV to define the variable
COPY . .
CMD ["python", "manage.py", "runserver"]Finally we want to run our application so we first copy everything and run a CMD build command but instead of a shell format we used a string array. This is when we start up our own container which uses this command to run our application.
Tip: You can use a .dockerignore file to prevent docker copying files you don't want copied
You can also run multiple containers in the same container using docker-compose but that is another thing
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