title: Spinnaker and custom Cloudwatch metrics for scaling policies
body: <p>I'm currently trying to get around the issue in AWS where CloudWatch alarms cannot contain more than one metric (in this case, SQS message counts). </p>
  
  <p>Scenario:</p>
  
  <p>I have an ASG that contains a set amount of on-demand instances for my application. I have another ASG, where I plan on using spot instances to scale out when it gets busy.</p>
  
  <p>What I'm trying to achieve is, for my application that consumes from 3 SQS queues</p>
  
  <ul>
  <li>if at least 1 queue has a message count above the threshold, scale out the spot instances ASG</li>
  <li>if ALL queues have a message count below the threshold for at least X minutes, scale in</li>
  </ul>
  
  <p>To get around this I'm attempting to publish a custom metric with a count of how many queues have a message count above a certain limit, and then use this metric to decide whether to scale in my auto scaling groups.</p>
  
  <p>However... in Spinnaker, there doesn't seem to be a way to refer to a custom metric (from the UI at least) - I am missing something here or is it just not possible? </p>
  
  <p>From what I understand as well, you can only publish metric data to your own namespaces - attempting to publish to any 'AWS/*' namespace will result in an error? </p>