Created: 2023-03-2710:40

What Is Docker?:

consistently build run and ship applications

• containers should contain everything that your application needs to run
  • package up everything that is needed
  • able to run anywhere that runs docker
• Isolated environments for applications to run

Problems with VMs

aka reasons containers are better

• each VM needs a full copy of an OS
• slow to start
• resource intensive

The Architecture of Docker

understanding how docker works

• client/server model
  • container & docker-engine
  • communication via REST API
• all containers share the kernel of the host OS
  • docker on mac uses a lightweight vm of Linux

Dev Workflow With Docker

• Dockerfile
  • plaintext file
  • Instructions to package the application into an image
• Images contain
  • cut-down OS
  • runtime env
  • application files
  • third-party files
  • env vars
• tell docker to start the container using the image
  • docker run ...

Docker In Action

• make application dir & cd to that dir
  • mkdir hello-docker; cd hello-docker
• create an “application” file app.js
  • add application code to file
• Instructions:
  • start with OS
  • Install Node
  • Copy app files
  • run node app.js

Building a Dockerfile

• start with the base image
  • FROM node:alpine
• copy app files
  • COPY . /app
• set working dir in container
  • WORKDIR /app
• run the app
  • CMD node app.js
• list images with docker image ls

References:

1. https://www.youtube.com/watch?v=pTFZFxd4hOI