DevOps Classroom notes 20/Dec/2023

Variables in Terraform

• To make terraform templates dynamic we need to accept user input and we accept user inputs in terraform using variables
• Refer Here for official docs
• Refer Here for the changes done to add a variable for a region
• Values to the variables can be passed by the user during terraform apply
  • by using teraform apply -var <variable-name-1>=<value-1> -var <variable-name-2>=<value-2> Refer Here
  • To handle multiple varibales terraform allows to create a file .tfvars extension where you can define variable values Refer Here
• Refer Here for the first version of variables

imporovement: avoid copy pastes

• Lets use count meta argument Refer Here
• Refer Here for the changes done

improvement: use functions

• use length function to determine number of resources to be created or passed to count
• Refer Here for the changes
• Use string interpolation. Refer Here
• Refer Here for using interpolation for dynamic cidr range calculation

Exercise

• Create a terraform template to
  • create a network (vnet/vpc)
  • with dynamic number of subnets based of cidr ranges subnet_cidrs = ["192.168.0.0/24", "192.168.1.0/24"]
  • subnet names should be like subnet0, subnet1
  • note: use variables (tfvars)