title: Cumulative sum of AWS Cloudwatch Metric
body: <p>AWS Cloudwatch receives a count of 1 every time I start an image download. I am downloading 1,000s of images (on a cluster of EC2 instances) and would like to track the total progress.</p>
  
  <p>I can't find any documentation on how to plot the cumulative sum of a metric. The AWS Cloudwatch Math Expressions looked promising, but they do not have an integrate function.</p>
  
  <p>Currently, I can plot the sum of the started image downloads but only for periods, as seen below. Ideally, I'd like to plot the integral of this plot:</p>
  
  <p><a href="https://i.stack.imgur.com/PjLiT.png" rel="noreferrer"><img src="https://i.stack.imgur.com/PjLiT.png" alt="AWS Cloudwatch Metrics"></a></p>