How do you put up a maintenance page for AWS when your instances are behind an ELB?

Question

How do you put up a maintenance page in AWS when you want to deploy new versions of your application behind an ELB? We want to have the ELB route traffic to the maintenance inst

Answer 1

As far as I could see, we were in a situation where the above answers didn't apply or weren't ideal.

We have a Rails application running the Puma with Ruby 2.3 running on 64bit Amazon Linux/2.9.0 that seems to come with a (classic) ELB.

So ALB 503 handling wasn't an option.

We also have a variety hardware clients that I wouldn't trust to always respect DNS TTL, so Route53 is risky.

What did seem to work nicely is a secondary port on the nginx that comes with the platform.

I added this as .ebextensions/maintenance.config

files:
  "/etc/nginx/conf.d/maintenance.conf":
    content: |
      server {
        listen 81;
        server_name _ localhost;
        root /var/app/current/public/maintenance;
      }

container_commands:
  restart_nginx:
    command: service nginx restart

And dropped a copy of https://gist.github.com/pitch-gist/2999707 into public/maintenance/index.html

Now to set maintenance I just switch my ELB listeners to point to port 81 instead of the default 80. No extra instances, s3 buckets or waiting for clients to fresh DNS.

Only takes maybe ~15s or so for beanstalk (probably mostly waiting for cloudformation in the back-end) to apply.