- severe unchangeable, undocumented limits before you get throttled. Throttling is so bad that if you have too many parameter store resources in your CloudFormation template it will start causing errors because CF is trying to call the API too quickly - the only way around it is to use DependsOn and chain the creation.
- no way of creating an encrypted value with CF without a custom resource.
We ended up just using DynamoDB for config anda Custom CloudFormation resource to create values in it.
You should never depend on Parameter Store as a reliable key/value store for configuration.
In any case, we do also use redis. It might be worthwhile to pitch an idea to move over to that. But we pull the parameters in bash scripts using a custom tool called aws-env, so we'd probably have to make or find something similar for redis.
I believe this is a new(ish?) feature, but someone from AWS Support recently pointed it out to me when dealing with throttling issues. Might be of interest to you.
https://aws.amazon.com/about-aws/whats-new/2019/04/aws_syste...
Holy mother of god, the search on it is horrific and simply doesn't work. Heartfelt begging through the feedback tool goes unanswered. I have offered money, firstborn children, sacrificial goats, virtually everything. But the search is still broken :( I've had to scroll through a hundred pages of parameters to find things.