Heroku is a cloud PaaS that supports several pre-configured programming languages. Heroku deals with all your infrastructure so you can focus on your application without having to work at the command line.
This article describes how to configure Heroku with Cloudflare to serve your traffic over HTTPS. For this article, we'll assume that you already have an active domain on Cloudflare, as well as a running Heroku app.
Add a custom domain to your Heroku app
- Log in to Heroku, select your app, and go to Settings.
- Scroll down to Domains and certificates and click Add Domain to add your domain.
If you are managing Heroku via CLI you can also add a domain with this command:
heroku domain:add [yourdomain]
Configure your Cloudflare DNS
IMPORTANT: Disregard the recommended Heroku CNAME created in the previous step (example.com.herokudns.com). Cloudflare's security and speed features cannot be used with this record. Instead, use the default Heroku domain name provisioned for your app (usually formatted like this cf-solutions.herokuapp.com).
Add a subdomain
To start, log in to your Cloudflare account, navigate to the DNS app and add the CNAME entry for your Heroku app.
Add your root domain
Adding a root or apex domain on Heroku requires using a CNAME record pointed from your root. You cannot use A records on Heroku because no IP addresses are exposed for Heroku users to use.
Fortunately, Cloudflare offers CNAME flattening to resolve requests for your root domain. Simply add a CNAME record for your root (e.g. kingkong.com) and point it to the same server name (cf-solutions.herokuapp.com).
Confirm that your domain is routed through Cloudflare
The easiest way to confirm that Cloudflare is working for your domain is to issue a cURL command.
╰─➤ curl -I www.kingkong.solutions
HTTP/1.1 200 OK
Date: Tue, 23 Jan 2018 18:51:30 GMT
Content-Type: text/html; charset=UTF-8
Set-Cookie: __cfduid=daeef1c4f83da8dd3ae5745d5e869b78e1516733490; expires=Wed, 23-Jan-19 18:51:30 GMT; path=/; domain=.www.kingkong.solutions; HttpOnly
Cache-Control: public, max-age=0
Last-Modified: Mon, 31 Dec 1979 04:08:00 GMT
You can identify Cloudflare-proxied requests by either the __cfuid cookie or the CF-Ray response header. If either of these two are present, your requests are being proxied by Cloudflare accordingly.
You can repeat the above cURL command for any of the sub-domains that you have configured within your DNS settings.
Configure your domain for SSL
- Cloudflare provides a SANs wildcard certificate with all paid plans, and a SNI wildcard certificate with the Free plan. Full details on SSL can be found here.
- If you don't know what this means, just navigate to the Crypto app in your Cloudflare dashboard. Select Flexible mode to serve your site over HTTPS to all public visitors:
Once the certificate status changes to • Active Certificate, incoming traffic will be served to your site over HTTPS (e.g., visitors will see HTTPS prefixed to your domain name in the browser bar).
Force all traffic over HTTPS
To force all traffic over HTTPS, you use the Page Rules app found in the Cloudflare dashboard:
Once you've navigated to the Page Rules app you can start adding a new rule that covers your entire domain:
Type in your page rule (i.e. 'http://*yourdomain.com/*) and click Save and Deploy.
You can then use a similar cURL command as before to verify that all requests are being forced over HTTPS.
╰─➤ curl -I -L kingkong.solutions
HTTP/1.1 301 Moved Permanently
Date: Tue, 23 Jan 2018 23:17:44 GMT
Expires: Wed, 24 Jan 2018 00:17:44 GMT
Please note that the issuing of a Universal SSL certificate typically takes up to 24 hours. Our paid SSL certificates issue within 10-15 minutes.