multistage Dockerfile tutorial

in this tutorial we are gonna work on our multistage Dockerfile skills.
We will create a dockerfile that runs a pipeline — covering build, lint,code analysis, test, and finally deployment. This will allow us to create a Container pipeline instead of building custom Jobs for every project in JENKINS or CircleCI for that matter. This will also allow us to seamlessly create container pipeline and reuse it with any CI/CD framework.

Pre requirements

• Docker installed

Our Dockerfile stages will be:

• Builder stage - getting our application files and installing requirements with python package manager pip
• Pylint stage - using it for error detection as a code analysis tool.
• Unit test stage - testing our code as a unit for a quick debugging before the integration test. Unit Test vs Integration Test
• Final stage - with that done a new image of our application will be created.

What we've accomplished:

• Our final image will have only the required files that it needs to run with and no Source code will be stored in it.

• It passed Lint tests and Unit tests in one shoot without a single push to central repo.

• Meaning that the developer don't need to wait for a CI/CD to run the tests or wait for his turn / job completion in the CI/CD.

• and of course the size - Multistage build vs single stage build