support more nodes than there are AZs defined

[gusse]

for loop to produce a list with the same amount of AZs as there are cache nodes. element() supports "wrap around" making it loop over the existing elements in var.availability_zones even if there aren't enough unique AZs for each node.

what

• Different method to populate the list of AZs that needs to match the number of cache nodes defined.

why

• Should be able to run more nodes than there are AZs defined in variable. Or for example more than 6 nodes (max number of AZs in any AWS region) in us-east-1 without providing a list with duplicate AZ names.

references

• Fixes Defining more cache nodes than you have availability zones is not supported #27
• https://www.terraform.io/docs/language/functions/element.html

[SweetOps]

/test all