title: 429 Rate exceeded responses for no apparent reason
body: <p>We're using Contentful to manage CMS content. When you save content in Contentful it sends webhooks for a service we've set up on Cloud Run, which in turn ensures the updated content is built and deployed.</p>
  <p>This setup has been previously so that the Cloud Run service was limited to 1 container max, with 80 concurrent requests limit. This should be plenty for the few webhooks we get occasionally.</p>
  <p>Now when debugging complaints about content not being updated I bumped into a very persistent and irritating issue - Google Cloud Run does not try to process the 2 webhooks sent by Contentful, but instead responds to one of the 2 with status <code>429</code> and <code>Rate exceeded.</code> in response body.</p>
  <p>This response does not come from our backend, I can see in the Cloud Run <code>Logs</code> tab the message generated by Google: <code>The request was aborted because there was no available instance.</code></p>
  <p>I've tried:</p>
  <ul>
  <li>Increasing number of processes on the container from 1 to 2 - should not be necessary due to use of an async framework</li>
  <li>Increasing number of containers from 1 to 2</li>
  </ul>
  <p>The issue persists for the webhooks from Contentful.</p>
  <p>If I try making requests from my local machine with <code>hey</code> that defaults to 200 requests with 50 concurrency, they all go through without any <code>429</code> status codes returned.</p>
  <p>What is going on that generates <code>429</code> status codes when a <em>specific client</em> - in this case Contentful - makes ONLY 2 requests in quick succession? How do we disable or bypass this behavior?</p>
  <p><code>gcloud run services describe &lt;name&gt;</code> gives me these details of the deployment:</p>
  <pre><code>+ Service [redacted] in region europe-north1
  
  URL:     https://[redacted].a.run.app
  Ingress: all
  Traffic:
    100% LATEST (currently [redacted])
  
  Last updated on 2021-01-19T13:48:46.172388Z by [redacted]:
    Revision [redacted]
    Image:            eu.gcr.io/[redacted]/[redacted]:c0a2e7a6-56d5-4f6f-b241-1dd9ed96dd30
    Port:             8080
    Memory:           256Mi
    CPU:              1000m
    Service account:  [redacted]-compute@developer.gserviceaccount.com
    Env vars:
      WEB_CONCURRENCY 2
    Concurrency:      80
    Max Instances:    2
    Timeout:          300s
  </code></pre>