WIP ARTICLE

Up until now, Docker has always been a mystery to me. Mostly because I never took time to dive into it. For the past year, I was lucky enough to have David Gageot as my manager at Doctolib. As far as I know, he was one of the early contributors to it, and remains to this day one of the main contributors. Docker has no secrets for him. Here is a video starring David himself, a year after Docker was released to the public:

During his time at Doctolib, I learned quite a lot. And I kept feeding my interest for Docker even after he left. Therefore this article serves as my personal cheatseet for Docker. It is a collection of basic knownledge and advanced tricks.

• Docker images can run nested Docker images (not advisable for production)
• FROM <image name>: sets the base image for our Docker image
• WORKDIR /home/yolo creates the /home/yolo directory
• CMD vs RUN: RUN is a build step, it creates a layer in the docker image and is therefore cached. CMD is the command to execute when runnning a docker image. If the command outputs something in stdin, it can be reused by other Docker images (see below).
• ADD . /home/yolo copy the output of the base image (through stdin) to /home/app. If the base image (FROM xxx) output assets as a result of its CMD command, the files will end up in /home/yolo.
• What's the difference between the docker commands: run, build, and create

• Basic common commands:

  • docker build -t toto .: builds an image from the Dockerfile in the current folder and labels it "toto"
  • docker run --init --rm -ti toto bash: starts a new container from the image labeled "toto" and opens a shell in it

Resources

• Best practices for writing Dockerfiles