Route 53 - Special domain for a single page on existing server - ruby-on-rails

Question

I have a complex web app at example-app.com, hosting fully on AWS using ELB and Route 53 for DNS. It's a Rails app.
I'm running an experiment that I'm using in the rails app, at example-app.com/test. I want to set up new-domain-app.com, to point at example-app.com/test, and have the URL cloacked to always be new-domain-app.com. It's a single page site, so it shouldn't require any navigation.
I'm having a lot of trouble figuring out how to set up my DNS on Route 53 to accomplish this. Does anyone have good ideas on what this Route 53 configuration should look like?

Answer 1

AWS offers a very simple way to implement this -- with CloudFront. Forget about the fact that it's marketed as a CDN. It's also a reverse proxy that can prepend a fixed value onto the path, and send a different hostname to the back-end server than the one typed into the browser, which sounds like what you need.
Create a CloudFront web distribution.
Configure the new domain name as an alternate domain name for the distribution.
For the origin server, put your existing hostname.
For the origin path, put /test -- or whatever string you want prefixed onto the path sent by the browser.
Configure the cache behavior as needed -- enable forwarding of the query string or cookies if needed and any headers your app wants to see, but not Host.
Point your new domain name at CloudFront... But before you do that, note that your CloudFront distribution has a dxxxexample.cloudfront.net hostname. After the distribution finishes setting up (the "In Progress" status goes away, usually in 5 to 20 minutes) your site should be accessible at the cloudfront.net hostname.
How this works: When you type http://example.com into the browser, CloudFront will add the origin path onto the path the browser sends, so GET / HTTP/1.1 becomes GET /test/ HTTP/1.1. This configuration just prefixes every request's path with the string you specified as the origin path, and sends it on to the server. The browser address bar does not change, because this is not a redirect. The host header sent by the browser is replaced with the hostname of the origin server when the request is sent to the origin.

Answer 2

What you are trying to do is not possible. Route53 is a DNS system, and you can not configure a hostname (e.g. new-domain-app.com) to point to URL (e.g. http://example-app.com/test) using DNS.
However, you are probably using a wrong tool for the job. If example-app.com/test is indeed a simple, static, single page site, then you do not need to host it inside Rails app. Instead, you can host it on AWS S3 bucket, and then you can point new-domain-app.com to that bucket using Route53.
See the following for details:
http://docs.aws.amazon.com/AmazonS3/latest/dev/WebsiteHosting.html
http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/RoutingToS3Bucket.html

Answer 3

DNS knows about Domains, not url's. DNS simply converts names to IP addresses.
You can't do what you are asking for just using DNS and ELB, however, what you can do is have a seperate VHOST for new-domain-app.com that points to your example-app.com site and accomplishes what you want using some sort of redirection rule that only fires for new-domain-app.com.
I'm not sure that this qualifies as an SO question, and more likely is a serverfault question. Specifics about your webserver and OS platform would be helpful in getting more specific advice.
So here's some details:
You already have example-app.com setup and working
You create a CNAME entry pointing new-domain-app.com to example-app.com or you can make an A record pointing to the same IP. If you already have example-app.com pointing to a different IP address, then use a subdomain (test.example-app.com) to isolate it.
Setup a new vhost on your server that basically duplicates the existing vhost for new-domain-app.com. The only thing you need to change is the server name configuration.
Why does this work? Because HTTP 1.1 included the HOST header that browsers send along, and web servers use in vhosting to determine which virtual host to route an incoming request to. When it sees that the client browser wanted "example-app.com" it routes the request to the appropriate vhost.
Rather than having to do some fancy proxying, which certainly can be used to get to a similar result, you can just add a redirection rule that looks for requests for the host example-app.com and redirects those to example-app.com. In apache that uses mod_rewrite which people often utilize by putting rules in the ubiquitous .htacess file, but can also be done in nginx and other common web servers. The specifics are slightly different for each.