plone.recipe.squid 1.0b1

Buildout recipe to install squid

Inspired by plone.recipe.varnish, plone.recipe.squid is a zc.buildout recipe to install Squid.

Even though the name contains “plone” there is nothing Plone specific about this recipe: it works with non-Zope sites just as well.

Configuration is very simple. For example:

[squid-build]
recipe = plone.recipe.squid:build
url = http://www.squid-cache.org/Versions/v2/2.6/squid-2.6.STABLE18.tar.gz

[squid-instance]
recipe = plone.recipe.squid:instance
bind = 127.0.0.1:3128
backends = 127.0.0.1:8080
cache-size = 1000

This configures two buildout parts: squid-build which will download, compile and install Squid and squid-instance which runs Squid, configured to listen on 127.0.0.1:3128 for requests, using a 1 gigabyte cache and sending requests to a backend at 127.0.0.1:8080.

Wrappers for the Squid commands are created in the bin directory of your buildout.

To start up Squid: ./bin/squid-instance

To shutdown Squid: ./bin/squid-instance -k shutdown

Virtual hosting

Squid supports virtual hosting by selecting a different backend server based on headers on the incoming request. You can configure the backends through the backends option:

[squid-instance]
backends =
   plone.org:127.0.0.1:8000
   plone.net:127.0.0.1:9000

This will generate a configuration which sends all traffic for the plone.org host to a backend server running on port 8000 while all traffic for the plone.net host is sent to port 9000.

Zope 2 hosting (with Virtual Host Monster)

If you are using Zope 2 as backend server you will need to rewrite the URL so the Zope Virtual Host Monster (VHM) can generate correct links for links in your pages. This can be done by another web proxy such as Apache or nginx (placed either in front or behind Squid) but can also be done by Squid itself.

The three options are described below.

Option 1 (rewrites after Squid):

If generating these VHM-style URLs in a proxy behind Squid (or if using VHM’s ‘mapping’ feature), no extra Squid configuration is needed. Just make sure the “backends” option directs the traffic to the proxy.

Option 2 (rewrites before Squid):

If generating these VHM-style URLs in a proxy in-front of Squid, no extra Squid configuration is needed as long as the original hostname is still retained in the URL. If the hostname is not retained, you can tell Squid to direct requests based on the “path” instead of the hostname. For example:

[squid-instance]
backends =
  /VirtualHostBase/http/plone.org:80/Plone:127.0.0.1:8000
  /VirtualHostBase/http/plone.net:80/Plone:127.0.0.1:9000

This will generate a configuration which sends all traffic for any request whose path starts with “/VirtualHostBase/http/plone.org:80/Plone” to a backend server running at 127.0.0.1 on port 8000, while request paths starting with “/VirtualHostBase/http/plone.net:80/Plone” are sent to port 9000.

Option 3 (rewrites within Squid):

To have Squid generate these VHM-style URLs, you can use the zope2_vhm_map option. Here is an example:

[squid-instance]
zope2_vhm_map =
    plone.org:/plone
    plone.net:/plone

This tells us that the domain plone.org should be mapped to the location /plone in the backend. By combining this with the information from the backends option a squid configuration will be generated that maps URLs correctly. Note: The ‘zope2_vhm_map’ option assumes delegation by ‘host’ so do not try to combine options 2 and 3 within the same config.

plone.recipe.squid:build reference

The plone.recipe.squid:build recipe takes care of downloading Squid, compiling it on your system and installing it in your buildout.

It can be configured with any of these options:

url

URL for an archive containing the Squid sources. Either url or svn has to be specified.

svn

URL for a subversion repository containing Squid sources. Either url or svn has to be specified.

squid-directory

The location of a shared Squid installation directory. Useful when building multiple Squid instances. A shared Squid build can be stored separate from the buildout instance. This directive must be defined in ~/.buildout/default.cfg similar to the “zope-directory” and “eggs-directory” directives. The default is to build Squid in a subfolder of the buildout ‘parts’ directory.

Please note that the configuration generated by this recipe requires Squid 2.6.STABLE18 or later. It is not tested with Squid 3.x.

plone.recipe.squid:instance reference

The plone.recipe.squid:instance recipe create a Squid configuration file and creates a wrapper script inside your buildout that will start Squid with the correct configuration.

Please note that Squid does not support spaces in path names so this recipe will not work if your buildout path contains any spaces.

Also note that the configuration generated by this recipe requires Squid 2.6.STABLE18 or later. It is not tested with Squid 3.x.

Squid-specific Configuration Options:

default-hostname

The default hostname to use if request is missing the Host header. Only needed if delegating to backend by Host header and there is the possibility of requests coming in from old or buggy clients. Defaults to the first hostname listed under ‘backends’.

visible-hostname

The hostname to show in squid-generated error pages. Defaults either to a hostname if specified by ‘bind’ or, if not, then to the value of ‘default-hostname’

visible-email

The email address to show in squid-generated error pages.

General Configuration Options:

daemon

The path of the squid daemon to use. Defaults to bin/squid inside your buildout, which is the executable created by the plone.recipe.squid:build recipe.

cache-size

The size of the cache in MB. Do not exceed 90% of available disk space. Defaults to 1000 MB.

bind

Hostname and port on which Squid will listen for requests. Syntax is [hostname][:port]. Defaults to 127.0.0.1:3128. If hostname is omitted then Squid will bind to all available interfaces.

config

Path for a Squid config file to use. If you use this option you can not use the backends or zope2_vhm_map options.

backends

Specifies the backend or backends which will process the (uncached) requests. The syntax for backends:

[<hostname>][/<path>]:<ip address>:<port>

The optional ‘hostname’ and ‘path’ allows you to do virtual hosting. If multiple backends are specified then each backend must include either a hostname or path (or both) so that Squid can direct the matching request to the appropriate backend. Defaults to 127.0.0.1:8080.

zope2_vhm_map

Defines a virtual host mapping for Zope servers. This is a list of hostname:ZODB location entries which specify the location inside Zope where the website for a virtual host lives.

user

The name of the user squid should switch to before accepting any requests. Defaults to ‘squid’.

group

The name of the group squid should switch to before accepting any request. This defaults to the main group for the specified user.

Reporting bugs or asking questions

A shared bugtracker and help desk is available on Launchpad: https://bugs.launchpad.net/collective.buildout/