Add a couple of AWS questions and exercises

EBS & ELB mainly.

exercises/aws/solutions/app_load_balancer.md

@@ -0,0 +1,35 @@
+## AWS ELB - Application Load Balancer 
+
+### Requirements
+
+Two EC2 instances with a simple web application that shows the web page with the string "Hey, it's a me, `<HOSTNAME>`!"
+
+### Objectives
+
+1. Create an application load balancer for the two instances you have, with the following properties
+  1. healthy threshold: 3
+  2. unhealthy threshold: 3
+  3. interval: 10 seconds
+2. Verify load balancer is working  (= you get reply from both instances at different times)
+
+### Solution
+
+#### Console
+
+1. Go to EC2 service
+2. Click in the left side menu on "Load balancers" under "Load balancing"
+3. Click on "Create load balancer"
+4. Choose "Application Load Balancer"
+5. Insert a name for the LB
+6. Choose an AZ where you want the LB to operate
+7. Choose a security group
+8. Under "Listeners and routing" click on "Create target group" and choose "Instances"
+  1. Provide a name for the target group
+  2. Set healthy threshold to 3
+  3. Set unhealthy threshold to 3
+  4. Set interval to 10 seconds
+  5. Click on "Next" and choose the two of the instances you've created
+  6. Click on "Create target group"
+9. Refresh target groups and choose the one you've just created
+10. Click on "Create load balancer" and wait for it to be provisioned
+11. Copy DNS address and paste it in the browser. If you refresh, you should see different message based on the instance where the traffic was routed to