Limit traffic without scaling out in Azure?

Question

Im looking into to use a Load Balancer in front of our API management, for example if a 1000 requests coming in in 5 second i want the 1001th request to be denied.

Which solution would work in this case?

Answer 1

API Management you can use Rate Limit policies:

The rate-limit-by-key policy prevents API usage spikes on a per key basis by limiting the call rate to a specified number per a specified time period.
The key can have an arbitrary string value and is typically provided using a policy expression. Optional increment condition can be added to specify which requests should be counted towards the limit. When this call rate is exceeded, the caller receives a 429 Too Many Requests response status code.

Example:

<policies>
    <inbound>
        <base />
        <rate-limit-by-key  calls="10"
              renewal-period="60"
              increment-condition="@(context.Response.StatusCode == 200)"
              counter-key="@(context.Request.IpAddress)"
              remaining-calls-variable-name="remainingCallsPerIP"/>
    </inbound>
    <outbound>
        <base />
    </outbound>
</policies>