# Full site CDN acceleration for Discourse

**URL:** https://meta.discourse.org/t/full-site-cdn-acceleration-for-discourse/21467
**Category:** Self-Hosting
**Tags:** cdn, explanation
**Created:** [October 24, 2014, 6:17am UTC](https://meta.discourse.org/t/full-site-cdn-acceleration-for-discourse/21467 "2014-10-24T06:17:57Z")
**Posts on this page:** 1
**Showing post:** 10

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### Author: ![ryanerwin](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/ryanerwin/32/94589_2.png) [@ryanerwin](https://meta.discourse.org/u/ryanerwin)
#### Post date: [May 20, 2018, 5:13pm UTC](https://meta.discourse.org/t/full-site-cdn-acceleration-for-discourse/21467/10 "2018-05-20T17:13:05Z")

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Some additional notes for anyone who decides to use HTTPS together with Full site CDN acceleration

1. Discourse internally uses the value of `SiteSetting.force_https` to decide if your `access-control-allow-origin:` is the HTTP or HTTPS version of your site. If while polling you see an error in the browser console along the lines of `preflight request doesn't pass access control check: The 'Access-Control-Allow-Origin' header has a value http doesn't match https`, double check your `force_https` setting. Also note the protocol in your `DISCOURSE_CORS_ORIGIN` in your container definition (http|https) will be overridden by `force_https`.  
Don’t forget to add `DISCORSE_ENABLE_CORS: true` in your container definition.

2. If you were planning to only do HTTPS from your end users to your CDN, and then HTTP from your CDN to your actual Discourse `web_only` containers, **lots of custom configuration** will be required.

3. If your CDN is serving your site on HTTPS, then whatever Long Polling URL you setup must also be on HTTPS, so even if the CDN is handling your HTTPS, you must still setup HTTPS on your Discourse servers. If you run into an error about `Same-origin policy`, double check that you’re not trying to connect to HTTP instead of HTTPS

4. You might use the following templates in your container definition:

```plaintext
  - "templates/web.template.yml"
  - "templates/web.ssl.template.yml"
  - "templates/fastly.template.yml"

```

- Towards the end of the `hook:ssl` inside `templates/web.ssl.template.yml` you’ll see this block being added to your `/etc/nginx/conf.d/discourse.conf`.

```nginx
if ($http_host != $$ENV_DISCOURSE_HOSTNAME) {
    rewrite (.*) https://$$ENV_DISCOURSE_HOSTNAME$1 permanent;
}

```

- You’ll need to need to comment these lines out, otherwise you’re long polling attempts always serve up 301 redirects back to your origin, instead of respecting whatever you set in `SiteSetting.long_polling_base_url`

1. The easiest way I’ve found to do this is to copy `templates/web.ssl.template.yml` to `local.web.ssl.template.yml` and just remove those extra lines, and update your container reference to use your local template. If you go that route, you should periodically `diff` your local version with the origional version, because there are some [security improvements that are regularly incorporated](https://github.com/discourse/discourse_docker/commits/master/templates/web.ssl.template.yml) into this template.

* * *

Some of the error messages you’ll run into until things are configured correctly.

> Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at [https://polling.example.com/message-bus/37c91c51e6cd4b0c95288b8fc29a0480/poll](https://polling.example.com/message-bus/37c91c51e6cd4b0c95288b8fc29a0480/poll). (Reason: CORS header ‘Access-Control-Allow-Origin’ missing).
> 
> Reason: CORS header ‘Access-Control-Allow-Origin’ missing
> 
> Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource
> 
> Failed to load [https://polling.example.com/message-bus/8caefcec2cf94de3ae684c4b953a1084/poll:](https://polling.example.com/message-bus/8caefcec2cf94de3ae684c4b953a1084/poll:) Response for preflight is invalid (redirect)

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_[View the full topic](https://meta.discourse.org/t/full-site-cdn-acceleration-for-discourse/21467)._