Reverse Proxy with Multiple Backend Web Servers

Source: http://wiki.squid-cache.org/ConfigExamples/Reverse/MultipleWebservers

Warning: Any example presented here is provided "as-is" with no support or guarantee of suitability. If you have any further questions about these examples please email the squid-users mailing list.

Contents

1. Reverse Proxy with Multiple Backend Web Servers
   1. Sending different requests to different backend web servers
   2. Squid Configuration
      1. Switching on Domains
         1. Other Criteria than Domain

Sending different requests to different backend web servers

To control which web servers (cache_peer) gets which requests the cache_peer_access or cache_peer_domain directives is used. These directives limit which requests may be sent to a given peer.

For example the websites are hosted like this on two servers:

• www.example.com hosted on server1
• example.com hosted on server1
• download.example.com hosted on server2
• *.example.net hosted on server2
• example.net hosted on server2

Squid Configuration

Switching on Domains

Simple config using cache_peer_domain

cache_peer ip.of.server1 parent 80 0 no-query originserver name=server_1
cache_peer_domain server_1 www.example.com example.com
cache_peer ip.of.server2 parent 80 0 no-query originserver name=server_2
cache_peer_domain server_2 download.example.com .example.net

Or the same using cache_peer_access:

cache_peer ip.of.server1 parent 80 0 no-query originserver name=server_1
acl sites_server_1 dstdomain www.example.com example.com
cache_peer_access server_1 allow sites_server_1


cache_peer ip.of.server2 parent 80 0 no-query originserver name=server_2
acl sites_server_2 dstdomain www.example.net download.example.com .example.net
cache_peer_access server_2 allow sites_server_2

Other Criteria than Domain

It's also possible to route requests based on other criteria than the host name by using other acl types, such as urlpath_regex.

For our example here the websites /foo directory alone is hosted on a second server:

• example.com is hosted on server1
• example.com/foo is hosted on server2

acl foo urlpath_regex ^/foo

cache_peer ip.of.server1 parent 80 0 no-query originserver name=server1
cache_peer_access server1 deny foo

cache_peer ip.of.server2 parent 80 0 no-query originserver name=server2
cache_peer_access server2 allow foo
cache_peer_access server2 deny all

Remember that the cache is on the requested URL and not which peer the request is forwarded to so don't use user dependent acls if the content is cached.

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CategoryConfigExample