Scenario of LT-Payroll Management System

• Learning Thoughts has developed a Payroll Management System
• The High level architecture of Payroll management System is
• Now lets look at implementation details
• Now lets look at their customers
• Now Learning Thoughts wants to add lot of features for their customers
  • EPFO Balance (401k)
  • Personal finance module
  • Integration with Banks for quick loan approvals
  • Insurance Purchase options
• Learning thoughts will be deploying small feature every two weeks with zero or minimal downtime
• Lets look at learning thoughts QA process before deploying
• Now to do this LT DevOps team has to perform lot of actions on different test environments
• For running tests we have scripts, all DevOps team needs to do is
  • to install application
  • run the scripts
• Our assumption is for every testing environment we have servers with operating system already available
• Now to install the application
  • we need to install some softwares
  • change some configurations
  • modify environmental variables etc.
  • install our application on top of it
• Since it has to be automated, lets see the possibilities
• Lets take a scenario of manager as shown below
• Lets take this analogy and apply to devops
• So, it will be easier for a devops engineer to work with configuration management tools like Ansible, chef, salt stack, puppet, cfengine … where devops engineer can express what has to be done in terms of configuring the system.
• The approach to speak looks like

ensure packages are upto date
ensure java is installed
ensure tomcat is installed
ensure tomcat service is running
ensure the file from https://lt-payroll/internals/app.war is downloaded to tomcat webapps folder

• Desired State: Desired state in CM is what you want
• Configuration Managment tools will always work to meet the desired state expressed
• In the case of procedural way

# ensure packages are upto date
sudo apt-get update
#ensure java is installed
sudo apt-get install openjdk-8-jdk -y
# ensure tomcat is installed
sudo apt-get install tomcat8 -y
# ensure tomcat service is running
sudo service start tomcat
#ensure the file from https://lt-payroll/internals/app.war is downloaded to tomcat webapps folder
cd /var/lib/tomcat8/webapps
wget https://lt-payroll/internals/app.war

• When we run declarative approach on the system where everything is configured

ensure packages are upto date  ---> packages are already upto date so i will not do anything
ensure java is installed   ---> Java is already installed so skipping this step
ensure tomcat is installed  ---> Since tomcat is already installed skipping this step

• when you run declarative approch on the same system multiple times the result will be same (Idempotance)

• In the procedural approach the result may or may not be the same on multiple executions

• Note:

  • Create Azure Free account Refer Here
  • Creating AWS Free tier account Refer Here
  • Create a simple Azure virtual machine Refer Here
  • Create an AWS EC2 instance Refer Here
  • Setting up and using windows terminal Refer Here
  • Install necessary softwares Refer Here