title: AWS communication between two applications EBS behind a shared ALB
body: <p>I have this architecture.</p>
  <p><a href="https://i.stack.imgur.com/FaKSw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FaKSw.png" alt="enter image description here" /></a></p>
  <p>EC2 instances are managed by Elastic Beanstalk where I have three different applications/environments, A B and C.</p>
  <p>Each environment is associated with an autoscaling group.
  The EC2 instances of each environment are associated with their target groups.</p>
  <p>The target groups are reached by a shared Application Load Balancer (wizard).</p>
  <p>The applications are Web API created with Spring Boot.</p>
  <p>From the ALB rules I am able to block requests from internet to A/stos*, B/stos* and C/stos* where by stos I mean service-to-service, services invoked by another internal application.</p>
  <p>However, I am unable to accept requests to A/stos*, B/stos* and C/stos* if they come from A, B or C.</p>
  <p>What is the correct way to go?</p>