Can Concurrent Rate Limit has one more TargetIdentifier

Google Cloud Apigee
1

This is Concurrent Rate Limit Policy

<ConcurrentRatelimit async="false" continueOnError="false" enabled="true" name="Concurrent-Rate-Limit-1">
    <DisplayName>Concurrent Rate Limit-1</DisplayName>
    <AllowConnections count="200" ttl="5"/>
    <Distributed>true</Distributed>
    <StrictOnTtl>false</StrictOnTtl>
    <TargetIdentifier name=""/>
</ConcurrentRatelimit>

I understand that TargetIdentifier name=“” means I have to Specifies the name of the TargetEndpoint.

  1. I want to know Can I have 2 TargetIdentifier in the same policy like this :
    <TargetIdentifier name="TargetEndpoint1"/>

    <TargetIdentifier name="TargetEndpoint2"/>

*I have to 2 Target Endpoints but I want to use only 1 Concurrent Rate Limit.

2.I have many flows in the same TargetEndpoint but I want to use 1 Concurrent Rate Limit/1 Flow. If I add condition for Concurrent Rate Limit, will it works? :

<Request>
   <Step>
      <Name>Concurrent-Rate-Limit-1</Name>
      <Condition>(proxy.pathsuffix MatchesPath "/path1")</Condition>
   </Step>
   <Step>
      <Name>Concurrent-Rate-Limit-2</Name>
      <Condition>(proxy.pathsuffix MatchesPath "/path2")</Condition>
   </Step>
</Request>
2
  1. TargetIdentifier is not exactly the name of target endpoints ,but unique identifier for which concurrent rate limit need to be applied. Apigee docs are a bit misleading on this.

so you can apply same policy/configuration to multiple targets but not using name but using TargetIdentifier as reference to context variables like request headers and other flow variables. For example

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ConcurrentRatelimit async="false" continueOnError="false" enabled="true" name="Concurrent-Rate-Limit-1">
    <DisplayName>Concurrent Rate Limit-1</DisplayName>
    <AllowConnections count="200" ttl="2"/>
    <Distributed>true</Distributed>
    <StrictOnTtl>false</StrictOnTtl>
    <TargetIdentifier ref="target.name"/>
</ConcurrentRatelimit>

This will maintain separate counter for each value of target.name . Using literal as name is just fixing the identifier to one value but it dosen’t necessarly have to be the name of TargetEndpoint.

  1. Yes you can use concurrent rate limit with conditions , just make sure to apply the same condition in targets PreFlow-request , PostFlow-response and DefaultFaultRule to avoid inconsistency.

Hope this will help.

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3

Thanks in advance.

4

Just FYI – ConcurrentRateLimit policy can result in lower throughput. Warning here: https://docs.apigee.com/api-platform/reference/policies/concurrent-rate-limit-policy

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