VMs v/s Dockers

• Introduction to Dockers and containers

Docker File

• A bunch of instructions (to package the application code and dependencies) that helps create a Docker Image
• Each operation is a layer in the file. If any change is made, only that layer is rebuilt

#format: INSTRUCTION arguments 
FROM python:3.8
LABEL maintainer="your-name"
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

Docker Image

• A read-only template that is used to spin-up a runnable instance of an application

# build an image
# OPTIONS - optional;  define extra configuration
# PATH - required;  sets the location of the Dockefile and  any referenced files 
docker build [OPTIONS] PATH

# Where OPTIONS can be:
-t, --tag - set the name and tag of the image
-f, --file - set the name of the Dockerfile
--build-arg - set build-time variables

# Find all valid options for this command 
docker build --help

Docker Registry

• A public registry where people can access your builds and images. (Similar to the NPM registry?)
• It's recommended to tag your images (otherwise an auto generated ID will be allocated to it)

Kubernetes

https://youtu.be/cC46cg5FFAM

• Open-source
• Portability
• Platform agnostic
• Scalability (HPA – Horizontal Portable Auto-scaler)
• Elasticity