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
