DevOps Classroomnotes 27/Aug/2023

Containerization using Dockerfile (contd..)

ADD and COPY: instructions to copy the contents into image

• For official docs of ADD Refer Here and COPY Refer Here
• Syntax

ADD <src> <dest>
COPY <src> <dest>

• ADD supports to copy from url’s whereas copy can copy from docker host into image

WORKDIR: working directory

• Refer Here for official docs

USER: sets the username

• Refer Here for the official docs

ARG: Parametrize while building image

• Refer Here for official docs
• ARG can provide a way to pass build time variables (they are available only during image building)

ENV: Environmental variables can be passed during container creation

• Refer Here for official docs

Building springpetclinic

• Refer Here for the changes to include add statement
• build the docker image with repo petclinic and tag v1.0.0-slim
  
• Running application from root folder mightnot be a good idea, lets create a directory for petclinic and run our application from there.
• Running application with root previleges poses security risks, so lets run the spring petclinic with a new user called as petclinic
• Refer Here for the changes done to accomodate user and workdir
• build the docker image with repo petclinic and tag v1.1.0-slim
  
• Now run the container in detached mode with name pcnew
  
• Build the image with username=qtdevops homedir=/lt petclinic and tag qt-slim
  
  
• Demonstrate usage of environmental variables, Refer Here for changes
  
• Now lets run the container and change the value of test while creation
  
  

Exercise

• Simple:
  • Gameoflife application: Refer Here for war file
    • requires:
      • jdk8
      • tomcat 8 or 9
    • Copy the war file into webapps folder of tomcat 9
    • Access the application by <tomcat-url>/gameoflife
• Tricky: Refer Here for nopCommerce on Linux
  • Note: dont focus on database, configure the rest.