Expected behavior for the Rate Limiting plugin with a path identifier

When configuring the Rate Limiting or Rate Limiting Advanced plugin with a path identifier, what is the expected behavior?

When configuring the Rate Limiting plugin (or Rate Limiting Advanced) with config.identifier=path it means the plugin will have a counter for the path configured and another counter for the paths that don’t match the configured path. For example:

• Configure a service to httpbin.org/anything

• Configure 3 routes for that service: /http1 /http2 /http3

• Configure the Rate Limiting plugin at the service level and set: identifier=path, strategy=local, path=/http1, window_size=[ 60 ], limit=[ 3 ], window_type=fixed

We are configuring 3 requests per minute. This means the plugin will have a counter for the path /http1 and a counter for the other paths (also using fixed window for an easier understanding). Let’s see an example:

• We are going to send 6 requests within the same window. We can confirm we are in the same window with the header RateLimit-Reset (RateLimit-Reset:53 throughout)

• We are going to send 4 requests to /http1. The first 3 will respond with a 200 OK and the forth 429 Too Many Requests (note RateLimit-Remaining:0)

• We are going to send 2 requests more, to /http2 and /http3. We still are in the same window (RateLimit-Reset:53). We see now both requests respond with a 200 OK as they use another counter. Also, you can see they use the same counter, for /http2 RateLimit-Remaining:2 and for /http3 RateLimit-Remaining:1

curl -I http://proxy.kong/http1
HTTP/1.1 200 OK
RateLimit-Reset: 53
RateLimit-Remaining: 2
RateLimit-Limit: 3
X-RateLimit-Limit-minute: 3
X-RateLimit-Remaining-minute: 2

curl -I http://proxy.kong/http1
HTTP/1.1 200 OK
RateLimit-Reset: 53
RateLimit-Remaining: 1
RateLimit-Limit: 3
X-RateLimit-Limit-minute: 3
X-RateLimit-Remaining-minute: 1

curl -I http://proxy.kong/http1
HTTP/1.1 200 OK
RateLimit-Reset: 53
RateLimit-Remaining: 0
RateLimit-Limit: 3
X-RateLimit-Limit-minute: 3
X-RateLimit-Remaining-minute: 0

curl -I http://proxy.kong/http1
HTTP/1.1 429 Too Many Requests
Retry-After: 53
RateLimit-Reset: 53
RateLimit-Remaining: 0
RateLimit-Limit: 3
X-RateLimit-Limit-minute: 3
X-RateLimit-Remaining-minute: 0

curl -I http://proxy.kong/http2
HTTP/1.1 200 OK
RateLimit-Reset: 53
RateLimit-Remaining: 2
RateLimit-Limit: 3
X-RateLimit-Limit-minute: 3
X-RateLimit-Remaining-minute: 2

curl -I http://proxy.kong/http3
HTTP/1.1 200 OK
RateLimit-Reset: 53
RateLimit-Remaining: 1
RateLimit-Limit: 3
X-RateLimit-Limit-minute: 3
X-RateLimit-Remaining-minute: 1

Note if we don’t configure any path, the plugin will only accept 3 requests per minute. In this case, it accepts 6 requests per minute:

• 3 for /http1

• 3 for either /http2 or /http3 (or any other path configured)