Nginx – How to cache web pages with a personalized header using caching reverse proxy such as Squid, Varnish, or Nginx

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Pretty much every page of my website is dynamically generated. However they don't change that frequently (kinda similar to a forum page). So I'd like to cache them using a caching reverse proxy such as Squid, varnish or Nginx.

The problem is that for my logged-in users, each of them will see a personalized header saying "Welcome John Doe. Logout" on the upper right corner of the page (just like serverfault). While users who aren't logged in will see a header that says "Login" instead.

So basically even though every user will see the same page in general, they all slightly different version due to that personalized header.

Is there any way so that I can cache the "main" part of the page and serve it from cache while generate the personalized header dynamically for each individual user?

This must be a very common problem. How is it solved in general?

Best Answer

With Varnish, you could use ESI, however, ESI processed pages are not able to be compressed without some added complexity. http://varnish-cache.org/wiki/ESIfeatures

I've not used this in production, but, Nginx also provides ESI functionality through a plugin, http://wiki.github.com/taf2/nginx-esi/

Nginx does provide caching through http://wiki.nginx.org/NginxHttpProxyModule#proxy_cache and with the other plugin, would handle both fragment assembly and caching.

http://www.trygve-lie.com/blog/entry/esi_explained_simple explains ESI.

Alternatively, you could do your own fragment caching on the application side.

Related Solutions

Nginx – How to Set Up as a Caching Reverse Proxy

I don't think that there is a way to explicitly invalidate cached items, but here is an example of how to do the rest. Update: As mentioned by Piotr in another answer, there is a cache purge module that you can use. You can also force a refresh of a cached item using nginx's proxy_cache_bypass - see Cherian's answer for more information.

In this configuration, items that aren't cached will be retrieved from example.net and stored. The cached versions will be served up to future clients until they are no longer valid (60 minutes).

Your Cache-Control and Expires HTTP headers will be honored, so if you want to explicitly set an expiration date, you can do that by setting the correct headers in whatever you are proxying to.

There are lots of parameters that you can tune - see the nginx Proxy module documentation for more information about all of this including details on the meaning of the different settings/parameters: http://nginx.org/r/proxy_cache_path

http {
  proxy_cache_path  /var/www/cache levels=1:2 keys_zone=my-cache:8m max_size=1000m inactive=600m;
  proxy_temp_path /var/www/cache/tmp; 


  server {
    location / {
      proxy_pass http://example.net;
      proxy_cache my-cache;
      proxy_cache_valid  200 302  60m;
      proxy_cache_valid  404      1m;
    }
  }
}

Varnish or Squid – Which is Good for web cache in small office

Varnish really isn't meant to be a general purpose web cache like Squid. From the Varnish FAQ:

Does that mean I can't use Varnish as a forward proxy? You can, but you probably don't want to. Doing it requires significant amounts of DNS magic and a huge Varnish VCL file.

You can configure squid as a transparent proxy (on Windows you need some third-party software to handle what iptables does on Linux) and alleviate the need to configure PCs to use the proxy.

Caching YouTube videos is a pain, irrespective of the transparency of the proxy. You can read about some of the problems caching YouTube content and see possible "workarounds" that may or may not work for you (or may stop working if YouTube makes changes).

Best Answer

Related Solutions

Nginx – How to Set Up as a Caching Reverse Proxy

Varnish or Squid – Which is Good for web cache in small office

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