Corey McKrill 4:42 pm on March 26, 2021
Tags: prio2 ( 100 )

Vary nginx cache by wporg_locale cookie value

This cookie gets set by the locale-detection pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party, which is used on the login site, and soon on the Learn WordPress site. In the case of Learn, the value of this cookie will determine the language that is displayed in the front end UIUI UI is an acronym for User Interface - the layout of the page the user interacts with. Think ‘how are they doing that’ and less about what they are doing. of the site (see this PR). Caching the pages without consideration of the chosen locale has a lot of potential for bad UXUX UX is an acronym for User Experience - the way the user uses the UI. Think ‘what they are doing’ and less about how they do it..

Could we update the nginxNGINX NGINX is open source software for web serving, reverse proxying, caching, load balancing, media streaming, and more. It started out as a web server designed for maximum performance and stability. In addition to its HTTP server capabilities, NGINX can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy and load balancer for HTTP, TCP, and UDP servers. https://www.nginx.com/. config to take this cookie into account when caching wporg pages? This locale switching functionality is intended for use on various wp.org sites beyond just Learn, so ideally this change would apply for *.wordpress.org

#~~prio1~~ because we’d like to get the locale switcher launched on the Learn site soon.

Bumping this down to #prio2 as it was worked around, but needs a call on whether this should just be closed or not.

Barry 3:08 am on March 27, 2021

Howdy – responses that have Set-Cookie in them are not cacheable, so I don’t think there is anything to vary the cache on.
- Corey McKrill 11:41 pm on March 29, 2021
  
  @barry Is proxy_ignore_headers Set-Cookie a no-go?
  
  What about adding the cookie value to the cache key? In the locale-detection pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party, the Set-Cookie headerHeader The header of your site is typically the first thing people will experience. The masthead or header art located across the top of your page is part of the look and feel of your website. It can influence a visitor’s opinion about your content and you/ your organization’s brand. It may also look different on different screen sizes. should only get set once on the request when the user chooses a locale…
- dd32 6:01 am on March 30, 2021
  @barry The issue is that the page response varies upon the value of the sent cookie and not every page response will include the Set-Cookie, so the cache needs to be varied upon the value of the request cookie (Not the page response) for example:
```
# No Cookie set, the page responds with a set-cookie, which does not get cached.
$ curl -is https://learn.wordpress.org/ | grep -E '^(set-cookie|cookie|x-nc|HTTP|<meta.+locale)'
HTTP/2 200
set-cookie: wporg_locale=en_US; expires=Wed, 30-Mar-2022 05:37:59 GMT; Max-Age=31536000; path=/; domain=.wordpress.org; secure
x-nc: EXPIRED ord 2
<meta property="og:locale" content="en_US" />

# The cookie is set on the client, Requests the site with the cookie, gets an en_US response that gets cached:
$ curl -is https://learn.wordpress.org/ -H 'Cookie: wporg_locale=en_US' | grep -E '^(set-cookie|cookie|x-nc|HTTP|<meta.+locale)'
HTTP/2 200
x-nc: MISS ord 1
<meta property="og:locale" content="en_US" />

# Requests with a de_DE cookie, get's the cached en_US response:
$ curl -is https://learn.wordpress.org/ -H 'Cookie: wporg_locale=de_DE' | grep -E '^(set-cookie|cookie|x-nc|HTTP|<meta.+locale)'
HTTP/2 200
x-nc: HIT ord 1
<meta property="og:locale" content="en_US" />

# A minute later, the en_US cache has expired, and a de_DE cookie result gets cached, and served to en_US visitors:
$ curl -is https://learn.wordpress.org/ -H 'Cookie: wporg_locale=en_US' | grep -E '^(set-cookie|cookie|x-nc|HTTP|<meta.+locale)'
HTTP/2 200
x-nc: HIT ord 2
<meta property="og:locale" content="de_DE" />
```
  What’s wanted in this case I think is something similar to this:
```
map $cookie_wporg_locale $vary_locale {
   ~^([a-z]{2,3}(_[A-Z]{2})?)$  $1;
   default '';
}
proxy_cache_key "$vary_locale$scheme$host$uri$is_args$args";
```
  proxy_ignore_headers Set-Cookie should not be used, as a request that sets the cookie should not be cached still.
  
  There’s a good chance that this kind of thing will be pushed onto other sites as well rather than just to learn.wordpress.orgWordPress.org The community site where WordPress code is created and shared by the users. This is where you can download the source code for WordPress core, plugins and themes as well as the central location for community conversations and organization. https://wordpress.org/ too, as it’s being done to avoid adding more content to the localised “rosetta” sites.
  It’s likely that developer.wordpress.org and a few make.wordpress.org handbooks will use it.
- Corey McKrill 10:14 pm on April 6, 2021
  
  As an interim measure, could we just not cache anything for learn.wordpress.orgWordPress.org The community site where WordPress code is created and shared by the users. This is where you can download the source code for WordPress core, plugins and themes as well as the central location for community conversations and organization. https://wordpress.org/?
Dion Hulse 2:41 am on August 25, 2021

This was partially resolved by forcefully setting a cookie for all learn.wordpress.orgWordPress.org The community site where WordPress code is created and shared by the users. This is where you can download the source code for WordPress core, plugins and themes as well as the central location for community conversations and organization. https://wordpress.org/ requests, and setting cache-control: no-cache, disabling the nginxNGINX NGINX is open source software for web serving, reverse proxying, caching, load balancing, media streaming, and more. It started out as a web server designed for maximum performance and stability. In addition to its HTTP server capabilities, NGINX can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy and load balancer for HTTP, TCP, and UDP servers. https://www.nginx.com/. caching for the domain.
chadworthman 6:12 pm on November 5, 2021

Howdy @dd32,

I have a tested configuration for adding $vary_locale to the proxy_cache_key that I’d like to commit on Monday.

I believe we’ll need the cache-control: no-cache backed out for it to work though. I’ll update on Monday.
chadworthman 3:00 pm on November 8, 2021

Good morning @dd32 and @coreymckrill.

$vary_locale has been added to the proxy_cache_key for learn.wordpress.org. We can add new hostnames to the map as needed.

Someone will need to disable cache-control: no-cache from the code.

Please let us know if you need any further assistance for this request.