brokers_per_zone instead of number_of_broker_nodes @Evilong (#63)
What
- Replace variable number_of_broker_nodes with broker_per_zone
- Default broker_per_zone as 1
- Validation on subnet_ids variable, should not be empty.
Why
- instead of relying on the input being a multiple of the subnets we can calculate the number_of_broker_nodes by multiplying the desired number of brokers per zone per subnets
- this behaviour is similar to the AWS Console UI approach (custom method) that requires the number of brokers per zone and subnets
- number of brokers per zone is a more understandable variable than number of broker of nodes