DevOps Classroom Series – 05/Mar/2020

Configuration Management

  • Need:
    • As part of CI/CD we need to create various environments, To create environments we need servers
    • Once the servers are available we need to perform technology specific and application specific operations/commands to run the application.
    • sample techonology specifics:

#
java application
=> linux server (ubuntu/centos)
    => installing java
    => application server to be configured
    (tomcat/jboss/whatever)
    => copy the package into some location
    => restart the app server

    => database server changes if required


.net application
	=> windows server
        => configure IIS
        => copy the package built into some folder




python application

=> Linux Server
=> Python
=> install django/flask
=> configure apache/nginx server to run python code
* Application Specific configurations
# some app specific configurations
Create environment variables
create/Delete some folders

Add database urls in some file

  • Possibilities:
    • Manual: Not an Option

    • Shell/Powershell Scripting:

      • Procedural
      • Pros: Stable technology & lot of knowledge around in existing teams
      • Cons:
        • Not Readable or Consistent among users.
        • Has assumptions and it is not guarnteed to give same results upon multiple executions.
      • Eg:
      # install tomcat
      # approach find and use commands
      sudo apt-get update && sudo apt-get install tomcat8 -y
      sudo systemctl enable tomcat8
      
      sudo yum update && sudo yum install tomcat8
      sudo systemctl enable tomcat8 
      sudo systemctl start tomcat8
      
    • Configuration Management:

      • Declarative
      • Simple to Learn
      • script should give same results upon multiple executions
      • Scripts should be Readable & Maintainable
      • Eg:
      # approach
      ensure packages are up to date
      enusure tomcat8 is installed
      enable and start tomcat8
      

Terms

  • Idempotance: When you run the script n times and are expected to get the same result , then the script is idempotent.

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