[squid-users] Squid Reverse Proxy (accel) always contacting the server

Hi,

This is what I want to obtain:

Environment:
* everything on the same machine (Debian GNU\Linux)
* server running on tomcat, port 8080
* squid running on port 280
* client can be anywhere, but for now it's on the localhost machine too

I want to set up an http cache to my tomcat server to reduce the load on it.

And I expect to obtain a result like this:

First request
1. 9:00 AM (today) client request GET to http://localhost:280/myservice
2. squid receive the request, nothing in cache, contact my server
3. tomcat reply with a 200, the body and some header:
Cache-Control: public, max-age=3600
Last-Modified: //8:00 AM//
4. squid store in cache that result that should be valid until 10:00 AM
(today) = 9:00 AM (time of the request) + 3600 seconds (max-age)
5. client receive the response

Second request:
1. 9:05 AM (today) client request GET to http://localhost:280/myservice
with header
If-Modified-Since: //8:00 AM//
2. squid receive the request, see 9:05 AM < 10:00 AM --> cache hit 304
3. client receive the response 304

Third request (after 10:00 AM)
1. 10:05 AM (today) client request GET to
http://localhost:280/myservicewith header
If-Modified-Since: //8:00 AM//
2. squid receive the request, see 10:05 AM > 10:00 AM --> time to see if
the server has a new version, forward the if-modified-since request to
the server
3. suppose the resource is not changed: tomcat reply with a 304 Not
Modified, again with headers:
Cache-Control: public, max-age=3600
Last-Modified: //8:00 AM//
4. squid store update the cache value to be valid until 11:05 AM (today)
= 10:05 AM (time of the request) + 3600 seconds (max-age)
5. client receive the response: 304 Not Modified

Instead squid is ALWAYS requiring the resource to the server:
$ curl -v -H 'If-Modified-Since: Thu, 29 Mar 2012 22:14:20 GMT'
'http://localhost:280/alfresco/service/catalog/products'

* About to connect() to localhost port 280 (#0)
* Trying 127.0.0.1...
* connected
* Connected to localhost (127.0.0.1) port 280 (#0)
> GET /alfresco/service/catalog/products HTTP/1.1
> User-Agent: curl/7.24.0 (x86_64-pc-linux-gnu) libcurl/7.24.0
OpenSSL/1.0.0h zlib/1.2.6 libidn/1.24 libssh2/1.2.8 librtmp/2.3
> Host: localhost:280
> Accept: */*
> If-Modified-Since: Thu, 29 Mar 2012 22:14:20 GMT
>
* additional stuff not fine transfer.c:1037: 0 0
* HTTP 1.0, assume close after body
< HTTP/1.0 304 Not Modified
< Date: Thu, 29 Mar 2012 23:27:57 GMT
< Cache-Control: public, max-age=3600
< Last-Modified: Thu, 29 Mar 2012 22:14:20 GMT
< Content-Type: application/json;charset=UTF-8
< Content-Length: 1158
< Server: Jetty(6.1.21)
< Age: 1
< X-Cache: HIT from localhost
< X-Cache-Lookup: HIT from localhost:280
< Via: 1.0 localhost (squid/3.1.19)
* HTTP/1.0 connection set to keep alive!
< Connection: keep-alive
<
* Connection #0 to host localhost left intact
* Closing connection #0

It say X-Cache: HIT

but I actually see the log in my server: the request is reaching it.
And since I have to do all the job but the rendering to check if the
content is changed this create an heavy load on the server.

Here my configuration:

the /etc/squid3/squid.conf (only added include on the top)

include /etc/squid3/accel8080.conf
acl manager proto cache_object
acl localhost src 127.0.0.1/32 ::1
acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1
acl SSL_ports port 443
acl Safe_ports port 80 # http
acl Safe_ports port 21 # ftp
acl Safe_ports port 443 # https
acl Safe_ports port 70 # gopher
acl Safe_ports port 210 # wais
acl Safe_ports port 1025-65535 # unregistered ports
acl Safe_ports port 280 # http-mgmt
acl Safe_ports port 488 # gss-http
acl Safe_ports port 591 # filemaker
acl Safe_ports port 777 # multiling http
acl CONNECT method CONNECT
http_access allow manager localhost
http_access deny manager
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
http_access allow localhost
http_access deny all
http_port 3128
coredump_dir /var/spool/squid3
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
refresh_pattern . 0 20% 4320

the included config file (my custom reverse proxy conf):

http_port localhost:280 accel ignore-cc
cache_peer 127.0.0.1 parent 8080 0 no-query originserver no-digest
default name=myAccel
refresh_all_ims off
acl Safe_ports port 280
http_access deny !Safe_ports
acl our_sites dstdomain 127.0.0.1
acl our_sites dstdomain localhost
http_access allow our_sites
cache_peer_access myAccel allow our_sites
cache_peer_access myAccel deny all

The startup log (cache.log):

2012/03/30 01:32:22| Starting Squid Cache version 3.1.19 for
x86_64-pc-linux-gnu...
2012/03/30 01:32:22| Process ID 23466
2012/03/30 01:32:22| With 65535 file descriptors available
2012/03/30 01:32:22| Initializing IP Cache...
2012/03/30 01:32:22| DNS Socket created at [::], FD 7
2012/03/30 01:32:22| DNS Socket created at 0.0.0.0, FD 8
2012/03/30 01:32:22| Adding nameserver 192.168.88.254 from /etc/resolv.conf
2012/03/30 01:32:22| Adding nameserver 192.168.1.1 from /etc/resolv.conf
2012/03/30 01:32:22| Unlinkd pipe opened on FD 13
2012/03/30 01:32:22| Local cache digest enabled; rebuild/rewrite every
3600/3600 sec
2012/03/30 01:32:22| Store logging disabled
2012/03/30 01:32:22| Swap maxSize 0 + 262144 KB, estimated 20164 objects
2012/03/30 01:32:22| Target number of buckets: 1008
2012/03/30 01:32:22| Using 8192 Store buckets
2012/03/30 01:32:22| Max Mem size: 262144 KB
2012/03/30 01:32:22| Max Swap size: 0 KB
2012/03/30 01:32:22| Using Least Load store dir selection
2012/03/30 01:32:22| Set Current Directory to /var/spool/squid3
2012/03/30 01:32:22| Loaded Icons.
2012/03/30 01:32:22| Accepting accelerated HTTP connections at
127.0.0.1:280, FD 14.
2012/03/30 01:32:22| Accepting HTTP connections at [::]:3128, FD 15.
2012/03/30 01:32:22| HTCP Disabled.
2012/03/30 01:32:22| Configuring Parent 127.0.0.1/8080/0
2012/03/30 01:32:22| Squid plugin modules loaded: 0
2012/03/30 01:32:22| Adaptation support is off.
2012/03/30 01:32:22| Ready to serve requests.
2012/03/30 01:32:23| storeLateRelease: released 0 objects

and the access.log while issue some request:

1. GET without any other header

1333064055.374 454 127.0.0.1 TCP_MISS/200 1519 GET
http://localhost/alfresco/service/catalog/products -
FIRST_UP_PARENT/myAccel application/json

2. GET without any other header (again)

1333064061.343 645 127.0.0.1 TCP_REFRESH_UNMODIFIED/200 1517 GET
http://localhost/alfresco/service/catalog/products -
FIRST_UP_PARENT/myAccel application/json

3. GET with If-Modified-Since header
1333064068.956 397 127.0.0.1 TCP_REFRESH_UNMODIFIED/304 369 GET
http://localhost/alfresco/service/catalog/products -
FIRST_UP_PARENT/myAccel application/json

please help me, I think I did what's in
http://wiki.squid-cache.org/SquidFaq/ReverseProxy but this is not
working and I lost too much time on the issue already trying to read and
experimenting on my own.

If I manage to make it work the next step is to make the cache work only
on /alfresco/service path on the service, any path including query
string ?key=value...
but for now I would be happy to solve this particular issue.

I also enabled full logging on squid3 to understand what's happening,
this is the log for the second request above (without any header):
http://pastebin.com/GhazwHCr

(too big to include in this email)

if you need any other information I would gladly provide it.

Thank you very much,
Regards,

Daniele Segato
Received on Thu Mar 29 2012 - 23:43:29 MDT