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POCorrect DNS setup for custom domain with subdomains and CNAMES pointing at them
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copied!<p>I have a multi-tenant Rails app, hosted with Heroku at <a href="http://myapp.herokuapp.com" rel="nofollow">http://myapp.herokuapp.com</a>. The tenants/accounts are separated via subdomains (and Postgresql schemas). I have then added my own domain as custom domain to the Heroku app. Since Heroku really advice against using A records because of "uptime implications" (<a href="https://devcenter.heroku.com/articles/avoiding-naked-domains-dns-arecords" rel="nofollow">https://devcenter.heroku.com/articles/avoiding-naked-domains-dns-arecords</a>) I first tried to put a CNAME record from my custom domain to myapp.herokuapp.com. That worked fine also with subdomains like <a href="http://clientaccount.mydomain.com" rel="nofollow">http://clientaccount.mydomain.com</a>.</p> <p>The problem began when my client wanted her own domain pointing to their account so that <a href="http://www.clientdomain.com" rel="nofollow">http://www.clientdomain.com</a> showed <a href="http://clientaccount.mydomain.com" rel="nofollow">http://clientaccount.mydomain.com</a>, the most obvious solution seemed to be to create a CNAME record in my clients DNS to point to <a href="http://clientaccount.mydomain.com" rel="nofollow">http://clientaccount.mydomain.com</a>. That did not work, when visiting the address an error message stated that "There is no app configured at that hostname", also <code>host www.clientdomain.com</code>gave:</p> <pre><code>www.clientdomain.com is an alias for clientaccount.mydomain.com clientaccount.mydomain.com is an alias for myapp.herokuapp.com myapp.herokuapp.com is an alias for ar.herokuapp.com </code></pre> <p>After some VERY confused support from Heroku, they advised my to use A records instead pointed to their three apex IPs. So changed it but it still didn't work. They then told me to add my clients domain as a custom domain in my Heroku settings which I have done without good result.</p> <p>So my current configuration is as follows:</p> <h2>Myapp at Heroku has following custom domains:</h2> <p>*.mydomain.com www.clientdomain.com</p> <h2>mydomain.com DNS</h2> <p>*.mydomain.com has three A records pointing at Heroku apex IPs</p> <h2>clientdomain.com DNS</h2> <p>In the DNS for clientdomain.com, clientdomain.com (without www) is redirected to www.clientdomain.com (Not sure how they do it but it seems to work.)</p> <p>For www.clientdomain.com there's a CNAME record pointing at clientaccount.mydomain.com</p> <h2>Current state</h2> <p>www.mydomain.com resolves correctly.</p> <p>clientaccount.mydomain.com resolves correctly.</p> <p>www.clientdomain.com goes to www.mydomain.com (without subdomain)</p> <p>So the problem is obvously either in the DNS somehow, does the subdomain fall away somewhere since my application obviously doesn't receive it? Or do I have to change some code in Rails in order to handle this?</p> <p>The subdomain is handled as route constraint, Subdomain class:</p> <pre><code>class Subdomain def self.matches?(request) request.subdomain.present? && Account.find_by_subdomain(request.subdomain) end end </code></pre> <p>Any input is appreciated!</p> <h2>EDIT</h2> <p>I have done everything that is suggested, do I have to change my application controller as well?</p> <p><strong>application_controller.rb</strong></p> <pre><code>def handle_subdomain if @account = Account.find_by_subdomain(request.subdomain) PgTools.set_search_path @account.id @current_account = @account else @current_account = nil PgTools.restore_default_search_path end end </code></pre>

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