== two JVMs (A on 8081, B on 8082), one redis-server on 6411; free-key-123 allows 5 per minute
request 1 to :8081 -> 200
request 2 to :8082 -> 200
request 3 to :8081 -> 200
request 4 to :8082 -> 200
request 5 to :8081 -> 200
request 6 to :8082 -> 429

$ curl -si -H 'X-API-Key: free-key-123' http://localhost:8081/api/hello
HTTP/1.1 429 
X-RateLimit-Limit: 5
X-RateLimit-Remaining: 0
X-RateLimit-Reset: 60
X-RateLimit-Scope: api-key
Retry-After: 12
Content-Type: application/problem+json

{"type":"about:blank","title":"Too Many Requests","status":429,"detail":"Rate limit exceeded for scope 'api-key'. Retry in 12 second(s).","retryAfterSeconds":12}


$ redis-cli -p 6411 --scan
rl:global
rl:key:ea39d5800282edc4