Configure throttling policies

Configure a throttling policy

1. You can configure a throttling policy within or outside a Cloud-native API Gateway instance.

   External API

   1. Log on to the Cloud-native API Gateway console. In the navigation pane on the left, click API. In the top navigation bar, select a region.

   2. Click the target API. From the drop-down list, select the instance for which you want to configure throttling, or select All Instances. From the instance drop-down list in the top navigation bar, select the target instance.

   3. In the Routes, click the target route.

   Internal API

   1. Log on to the Cloud-native API Gateway console. In the navigation pane on the left, click Instance. In the top navigation bar, select a region.

   2. On the Instance page, click the ID of the target gateway instance. In the navigation pane on the left, click API, and then click the target API.

   3. In the Routes, click the target route.

2. Click the Configure Policy tab, and then click Enable Policy/Plug-in in the Inbound Processing section.

3. Add a throttling policy. Options include Traffic Control, Concurrency Control, and Circuit Breaking.

   Traffic Throttling

   Throttling rules monitor the QPS of a route and block traffic immediately when the threshold is reached, preventing backend service breakdowns due to traffic surges.

   Click the Traffic Control card. In the Add Policy:Traffic Control panel, configure the parameters and then click Add.

   Parameter	Description
   Enable or Not	Turn on this switch to enable the traffic control policy.
   Overall QPS Threshold	The Overall QPS Threshold.
   Web Fallback Behavior	Set Web Fallback Behavior to Return Specific Content or Redirect to Specified Page.
   If you set Web Fallback Behavior to Return Specific Content:
   HTTP Status Code	The HTTP Status Code to return. The default value is 429.
   Type of Returned Content	The Type of Returned Content of the response body. You can select Regular Text or JSON.
   HTTP Text	The text to return.
   If you set Web Fallback Behavior to Redirect to Specified Page:
   Redirect URL	The Redirect URL.

   Concurrency control

   Concurrency rules track the total number of requests being processed by the gateway and block traffic when the count reaches the specified threshold, protecting backend service availability during high-concurrency scenarios.

   Click the Concurrency Control card. In the Add Policy: Concurrency Control panel, configure the parameters and then click Add.

   Parameter	Description
   Enable or Not	Turn on this switch to enable the concurrency rule.
   Overall Concurrency Threshold	The Overall Concurrency Threshold.
   Web Fallback Behavior	Set the Web Fallback Behavior to Return Specific Content or Redirect to Specified Page.
   If you set Web Fallback Behavior to Return Specific Content:
   HTTP Status Code	The HTTP Status Code to return. The default value is 429.
   Type of Returned Content	The Type of Returned Content of the response body. You can select Regular Text or JSON.
   HTTP Text	The response body to return.
   If you set Web Fallback Behavior to Redirect to Specified Page:
   Redirect URL	The Redirect URL.

   Circuit breaking

   Circuit breaking rules trip when the response time (RT) or exception ratio on a route reaches a specified threshold. Once tripped, the gateway rejects all requests on that route for a configured duration to protect backend services, then resumes calls automatically.

   Click the Circuit Breaking card. In the Add Policy: Circuit Breaking panel, configure the parameters and then click Add.

   Parameter	Description
   Enable or Not	Turn on this switch to enable the circuit breaking rule.
   Statistical Window Duration	The duration of the time window. Valid values: 1 second to 120 minutes.
   Minimum Number of Requests	The minimum number of requests required to trigger circuit breaking. If the request count in the current time window is below this value, circuit breaking is not triggered even if the threshold condition is met.
   Threshold Type	The metric used to trigger circuit breaking. You can select Slow Call Ratio (%) or Exception Ratio (%). If you select Slow Call Ratio (%), you must set a Slow Call RT, which is the maximum response time. A request is considered a slow call if its response time is greater than this value. Once the rule is enabled, if the number of requests in a statistical window exceeds the minimum number of requests and the slow call ratio exceeds the specified threshold, requests are rejected for the circuit breaking duration. After the circuit breaking duration, the circuit breaker enters a probing recovery state. If the next request's response time is less than the specified Slow Call RT, the circuit closes. Otherwise, the circuit opens again. If you select Exception Ratio (%), you must set the exception ratio that triggers circuit breaking. Once the rule is enabled, if the number of business exceptions in a statistical window exceeds the minimum number of requests and the exception ratio exceeds the threshold, requests are rejected for the duration of the circuit breaking period.
   Slow Call RT	The allowed Slow Call RT (maximum response time).
   Circuit Breaking Ratio Threshold	The percentage threshold for slow calls. Circuit breaking is triggered when this threshold is reached or exceeded. Valid values: 0 to 100 (%).
   Circuit Breaking Duration (s)	The duration for which circuit breaking stays active. During this period, all requests to the route are rejected.
   Web Fallback Behavior	Select Web Fallback Behavior as Return Specific Content or Redirect to Specified Page.
   If you set Web Fallback Behavior to Return Specific Content:
   HTTP Status Code	The HTTP Status Code to return. The default value is 429.
   Type of Returned Content	The Type of Returned Content of the response body. You can select Regular Text or JSON.
   HTTP Text	The response body to return.
   If you set Web Fallback Behavior to Redirect to Specified Page:
   Redirect URL	The Redirect URL.

Verify results

curl -I http://121.196.XX.XX/demo/item/list     //The ingress IP address of the gateway.

• A response similar to the following is returned if the throttling policy is not enabled:

  HTTP/1.1 200 OK
  x-content-type-options: nosniff
  x-xss-protection: 1; mode=block
  cache-control: no-cache, no-store, max-age=0, must-revalidate
  pragma: no-cache
  expires: 0
  x-frame-options: DENY
  content-type: application/json
  content-length: 86
  date: Mon, 29 Nov 2021 08:28:00 GMT
  x-envoy-upstream-service-time: 4
  server: istio-envoy

• If the throttling policy is enabled, a response similar to the following is returned with HTTP status code 429.

  HTTP/1.1 429 Too Many Requests
  x-local-rate-limit: true
  content-length: 18
  content-type: text/plain
  date: Mon, 29 Nov 2021 08:28:01 GMT
  server: istio-envoy