Squid Proxy Customizations at UCSD T2

Contents

Introduction

UCSD runs a squid proxy for the use of any OSG users that would like to take advantage of the benefits of a local HTTP/FTP proxy. The most significant benefits are for those VOs that use http protocol for the distribution of code, data or meta-data to individual jobs. Instead of each job generating a request to a central VO source the squid proxy can use its cache ability to make subsequent data requests come from the local proxy instead of the remote VO source.

Using the UCSD Squid Proxy

The UCSD CE sets two environment variables to assist jobs in the use of the squid proxy.

http_proxy

The environment variable http_proxy is set for all jobs submitted to the UCSD T2 center. The http_proxy variable is a widely used standard for specifying a local http proxy to a variety of web tools including links(1), wget(1) and curl(1).

Some HTTP agent libraries for various scripting languages also honor the *_proxy environment variables including Perl's LWP::UserAgent(3).

OSG_SQUID_LOCATION

UCSD sets the OSG_SQUID_LOCATION variable to the same value as http_proxy. OSG_SQUID_LOCATION is an OSG standard environment variable and can be used to pass the correct http proxy location to custom programs or programs that do not adhere to the http_proxy standard.

Authors

-- TerrenceMartin - 17 May 2007