What is a Dockerfile?

It contains instruction that docker uses to package up an application into an image.

Containers and Images , What are these?

Images : An image includes everything an application needs to run. It includes application files, environment variables and so on.

Container : Once we have an image, we can start a container from it. A container is like a VM in a sense that it provides an isolated environment for executing an application. Similar to VM we can stop and restart a container.

Simplified Analogy: Think of images as a class(blueprint) and containers as running instance(objects) for that blueprint.

Steps to create a Dockerfile:

Choose a correct base image

Setup the working directory

Copy application files into the image. Example: COPY <source> <destination>

Exclude files & folders(node_modules, venv, etc)

Adding environment variables

Exposing ports

By default docker runs an application with the root user that has the highest privileges.

Diff.…