I am having long cold start times on our Lambda functions. We have tried "pinging" the Lambdas to keep them warm but that can get costly and seems like a poor way to keep performance up. We also have an EC2 instance running 24/7. I could theoretically "mirror" all of our Lambda functions to our EC2 instance to respond with the same data for our API call. Our Lambdas are on https://api.mysite.com and our EC2 is https://dev.mysite.com.
My question is could we "load balance?" traffic between the two. (Create a new subdomain to do the following) To have our dev subdomain (EC2) respond to all requests up until a certain "requests per minute" is hit. Then start to route traffic to our dev subdomain (Lambda) since we have enough traffic coming in to keep the Lambdas hot. Once traffic slows down, we move the traffic back over to our EC2.. Is this possible?
No, you can not do that with AWS Load balancer. What you can do is setup cloudwatch trigger to the lambda function which will map api.mysite.com to the lambda load balancer dns. Similarly, you can add trigger for low traffic which will redo dns entry.
If you are aware of rise in traffic, you can scheduled instances. Else you can also try AWS Fargate.
Hope this helps you.