Table of contents

Advantages of docker

  • Same environment everywhere
  • Sandbox projects

Difference between virtual machine and container

  • VM needs a kernel and container doesnt need kernel. So VM is more resource heavy for a host machine.
  • Uses less memory and resources.
  • Stacking of images means that creating a process doesnt need to start from scratch. Eg. to run jupyter, a pre installed anaconda image will be available on docker hub.

How it works

  • Uses container which is the running instance of an ima.ge which is snapshot of a system at any given time.
    • It has got the OS, application codes softwares all bundled in a file.
  • Images defined using Dockerfile
    • Text file with steps to create image, like install softeare, move files etc.

How to install

Simpler application using docker run

This video contains good steps for a hello world application. Steps to follow are as follows:

  • Install docker for Mac/windows or Linux
  • Create application folder src (eg. a python print hello world program)
  • Create Dockerfile outside application folder
    • configure docker file
      • get a ready made image from docker hub (eg. official python image)
      • add the following to docker file 
          FROM <specify image name from docker hub>
  COPY src/ /<folder path in image specified in docker hub>
  EXPOSE <port number>
  • Build docker 
    docker build -t hello-world . <. means same directory>
  • Launch docker using run 
    docker run -p 80:80 <guest:host mapping>

    Doing this will reflect changes made on host to guest.

    docker run -p 80:80 -v <host path>:<guest path>

    Endeavour to have one process per container. As if python crashes it takes the container with it.

Microservices using docker compose

This video contains good steps for a hello world application.