Activity 2: Create a network with 6 subnets
- While creating subnet we need to pass the vpc id, but vpc id will be known after the stack is created, so there should be a way to dynamically refer the vpc id
- Every AWS Cloud formation resource has return values Refer Here for return values of vpc
- As per documentation there are two ways
- Ref
- Fn::GetAtt
- Ref and Fn::GetAtt are built in functions of Cloudformation Refer Here for the ref usage
- We have create a cf template with six subnets and created the stack
- For the changes Refer Here
- The template developed so far has two major problems in terms of reusability
- It works only in oregon (us-west-2)
- It has fixed cidr ranges
- Lets try to solve the problem of fixed cidr ranges first.
- I want user to be able to enter cidr ranges of his choice with the current values as default values
- Parameter in AWS Cloud formation can help in solving this problem Refer Here
- We have create two parameters. One for vpc cidr which is string and other for subnet cidrs which comma-seperated strings
- Refer Here for the changes done
- AWS Specific parameters are values dynamically made available by AWS Refer Here
- We have used Availability zone name type parameter . This parameter removes the region dependency and the template can now work in any region. Refer Here for the chagnes done
