DevOps Classroom Series – 18/Oct/2020

Terraform contd..

• Manual Steps:
  • Create a mysql rds instance in the dbsubnet group
    • instance size: db.t2.micro
    • sql database engine: mysql
    • version: 5.7
    • security group
    • credentials
• Terraform Steps
  • Security group creation: For changes Refer Here
  • Lets create an rds instance. For changeset Refer Here
• Next Steps:
  • Lets create an ec2 instance in app subnet
  • Login into ec2 instance and execute the following commands

  sudo apt update
  sudo apt-cache search tomcat
  sudo apt install tomcat8 tomcat8-admin tomcat8-common tomcat8-docs tomcat8-examples -y
  cd /var/lib/tomcat8/webapps/
  sudo wget https://referenceappkhaja.s3-us-west-2.amazonaws.com/gameoflife.war
  

• Automating above steps using terraform.
  • Create a security group for app server Refer Here
  • Creating an ec2 instance can be done by terraform resource but here we need to login into ec2 instance and install software/configuration. We have two options
    • Try to create ec2 instance with image already containing software and configuration. (Automation of image creation can be done using Packer which we will be learning very soon)
    • Create an ec2 instance from terraform and provision the application using
      • shell scripts
      • Ansible
      • Salt Stack
      • Chef
      • Powershell Scripts
  • To Perform provisioning terraform has provisioners. Refer Here
  • When we are using provisioners we need to login into virtual machines which are generally windows or linux machines. To enable login into these vm’s terraform has Connection Refer Here
  • Terraform has a file provisioner Refer Here which can copy the files from local machine (Where terraform is executing) into remote machine (Machine created by terraform)
  • Terraform has a local-exec provisioner Refer Here which is used to run the executable on the local machine (where terraform is executing)
  • Terraform has a remote-exec provisioner Refer Here which is used to run the executable on the remote machine (machine created by terraform)
  • Terraform also has
    • chef provisioner Refer Here
    • habitat provisioner Refer Here
  • Now if we observer our case,
    • we need to create ec2 instance => We can use terraform resource
    • login into the machine => We can use Provisioner Connection
    • execute the set of linux commands => We can use remote-exec
  • Refer Here for the changes done to the terraform script