Simple Plone Clustering with Squid and Pound

There are so many how-tos out there on how this is supposed to be setup, but each seem to be missing one part or adds in some extra complexities that aren't really needed.

1. Pound is super simple to setup
2. ZEO is a little more difficult
3. Squid is the most complex

In this setup no redirector script is needed for squid since we can handle the mappings in the VirtualHostMonster mappings tab. We have to run pound and squid on the same port, but different interfaces so the url rewriting does the right thing. VirtualHostMonster itself won't rewrite the ports without some kind of rewriting done beforehand. This is ok since we can just bind Pound to the loopback interface and the squid to the external interface.

Here is a copy of my squid.conf. Just replace @@my.domain.com@@ with the host name that you are serving and @@my_external_ip_address@@ with the external IP of your server:

    hierarchy_stoplist cgi-bin ?
    acl QUERY urlpath_regex cgi-bin \?
    no_cache deny QUERY
    auth_param basic children 5
    auth_param basic realm Squid proxy-caching web server
    auth_param basic credentialsttl 2 hours
    auth_param basic casesensitive off
    refresh_pattern ^ftp:               1440    20%     10080
    refresh_pattern ^gopher:    1440    0%      1440
    refresh_pattern .           0       20%     4320
    # Basic ACLs
    acl all src 0.0.0.0/0.0.0.0
    acl localhost src 127.0.0.1/32
    acl ssl_ports port 443 563
    acl safe_ports port 80 443
    acl zope_servers src 127.0.0.2 127.0.0.1 
    acl manager proto cache_object
    acl connect method connect
    # deny requests to unknown ports
    http_access deny !safe_ports
    acl accelerated_protocols proto http https
    acl accelerated_domains dstdomain @@my.domain.com@@
    acl accelerated_ports myport 80 443 
    http_access allow accelerated_domains accelerated_ports accelerated_protocols
    # Purge access - zope servers can purge but nobody else
    acl purge method PURGE
    http_access allow zope_servers purge
    http_access deny purge
    # Reply access
    http_reply_access allow all
    # Cache manager setup - cache manager can only connect from localhost
    # only allow cache manager access from localhost
    http_access allow manager localhost
    http_access deny manager
    # deny connect to other than ssl ports
    http_access deny connect !ssl_ports
    # ICP access - anybody can access icp methods
    icp_access allow localhost
    # And finally deny all other access to this proxy
    http_access deny all
    coredump_dir /usr/local/squid/cache
    http_port @@my_external_ip_address@@:80
    httpd_accel_host 127.0.0.1
    httpd_accel_port 80
    httpd_accel_single_host on
    httpd_accel_with_proxy on
    httpd_accel_uses_host_header on 

Pound's 1.X config is simple also:

  ListenHTTP 127.0.0.1,80
  User zope
  Group zope
  LogLevel 1
  UrlGroup ".*"
  BackEnd 127.0.0.1,51003,1
  BackEnd 127.0.0.1,51004,1
  EndGroup

Here is the same thing for pound 2.X:

    User "zope"
    Group "zope"

    ListenHTTP
      Address 127.0.0.1
      Port 81
      xHTTP 2
    End

    Service
        BackEnd
            Address 127.0.0.1
            Port  51003
        End
        BackEnd
            Address 127.0.0.1
            Port  51004
        End
       Session
          Type    COOKIE
          ID      "__ac"
          TTL     300
       End
    End

All that is left is to configure 2 ZEO Clients and a ZEO Storage Server to answer the requests. In one of the ZEO Clients go into the root VirtualHostMonster and on the mappings tab add one entry per domain name and site you want to serve.