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I'm stuck on a configuration and hoping someone can help me break through. I have a single EC2 instance behind an ELB, but can't seem to bring that instance into service. If I remove the ELB, I can connect to the status check URL just fine. Here are the details:

  • The EC2 instance and the ELB are in the same VPC
  • The ELB belongs to a security group that allows access to :443 from anywhere (0.0.0.0/0).
  • The ELB port config is: 443 (HTTPS, ACM Certificate: xxx) forwarding to 80 (HTTP)
  • I can telnet to the ELB on :443.
  • The EC2 instance belongs to a security group that allows access to :22 from anywhere and to :80 from the ELB security group.
  • I've tried opening up :80 access on the EC2 instance, but that made no difference.
  • I can connect directly to the EC2 instance on :80 (telnet or http) when access to :80 is opened up, but the instance remains out of service to the ELB.

There's no indication that the ELB is able to connect to the EC2 instance at all. Tailing my nginx access log shows no ELB-generated requests for my health check URL.

Any idea what I might be missing here or what I might need to check?

  • What does your health check page return? Is it a plain 200? – Matt Houser Jul 26 '16 at 12:26
  • it should, but I can't see any evidence that the web server is ever being reached. – Rob Wilkerson Jul 26 '16 at 12:34
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First you should check your configuration of health-check in ELB. Misconfiguration there can lead to such consequences.

Also you can try disabling Source/Destination check in settings of EC2 instance.

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    Why would source/destination check have anything to do with this? It doesn't. That should only ever be used on instances that are performing routing functions. – EEAA Jul 26 '16 at 11:34
  • I can reach the health check URL (HTTP:80/status) manually once I open up access to more than the ELB. I can't see anything that looks amiss there, but I'm wrong about something. Maybe it's this. 🙂 – Rob Wilkerson Jul 26 '16 at 11:36
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My bad, folks. I completely forgot that the ELB executes the heath check request via the internal IP address of its instances (e.g. http://XXX.XXX.XXX.XXX/status). My web server wasn't listening for anything on that particular IP. Argh.

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