squid.conf and Squid 2.6 vs. Squid 2.7

[Michael Lenaghan <michaell@xxxxxxxxxx>]

I used a Python recipe from PyPi to build, install and configure
Squid. The same recipe, config, etc. breaks when moving from Squid 2.6
to Squid 2.7. Other people have reported seeing the same error but no
one has bothered to track down a fix. I have one now, but I really
only got it by trying a bunch of different things. Before reporting
the fix back to various groups I'd like to understand what broke and
why the change made a difference.

In my particular case Squid was being used as a reverse (caching)
proxy in an Nginx -> Squid -> Zope chain. Squid was running on port
10932 and Zope on 45086. With 2.6 everything worked, but when
switching to 2.7 Squid's port number became visible in URLs. For
example, in the main page the href to the logo appeared as:

http://[domain]:10932/logo.jpg

rather than:

http://[domain]/logo.jpg

I've pasted the original conf file below (with domain names and such
abstracted out), but the fix involved the addition of vport=80 to the
http_port line:

http_port 127.0.0.1:10932 accel vhost vport=80 defaultsite=[domain]

I've had a very difficult time finding good docs for vhost, vport and
defaultsite. I've looked and I've searched in many places, but I
haven't found anything that would help me explain *why* this change
worked. Indeed, the bits I did find made me think that perhaps you
don't need defaultsite when you're using vhost--but I'm not even sure
about that!

(The 2.7 change notes say that for http_port "Accelerator mode options
cleaned up (accel, defaultsite, vport, vhost and combinations
thereof)". Is the difference in behaviour here related to that
clean-up?)

If anyone can explain--or point me to the explanation I missed--I'd
appreciate it.

=== squid.conf created by plone.recipe.squid

# This configuration file requires squid 2.6+.  It is untested with squid 3.x.

visible_hostname [domain]
http_port 127.0.0.1:10932 accel vhost defaultsite=[domain]
pid_filename /home/[user]/webapps/plone/var/squid.pid

## Log files (http://wiki.squid-cache.org/SquidFaq/SquidLogs)
cache_access_log /home/[user]/webapps/plone/var/log/squid-access.log
cache_log /home/[user]/webapps/plone/var/log/squid-cache.log
cache_store_log none

# Cache storage
cache_dir ufs /home/[user]/webapps/plone/var/squidstorage 1000 16 256
cache_mem 64 MB
maximum_object_size 10 MB
maximum_object_size_in_memory 1 MB

# Purge access - zope servers can purge but nobody else
# (works best if Zope and Apache are on different IPs)
acl zope_servers src 127.0.0.1
acl purge method PURGE
http_access allow zope_servers purge
http_access deny purge

# Deny caching of POST requests
acl post_requests method POST
cache deny post_requests

# Cache Peers
cache_peer 127.0.0.1 parent 45086 0 no-query originserver login=PASS
name=server_0

# Cache Peer Access
acl all src 0.0.0.0/0.0.0.0

cache_peer_access server_0 allow all