I'm confused by your reference to "gatekeeper EC2 instances." In the scenario I described, the secrets are housed on S3, not a separate EC2 instance. So, theore

I'm confused by your reference to "gatekeeper EC2 instances." In the scenario I described, the secrets are housed on S3, not a separate EC2 instance. So, theoretically, as long as the underlying instance running the application code can access S3, and S3 doesn't go down (very unlikely), there shouldn't be any issues.