The cache_config tool is designed to work with Condor’s "Configuration with Pipes" feature, enabling users to fetch Condor configuration files from web servers, web applications or anything that can be represented using a URL.

It supports expiring, local file caching to reduce the number of calls triggered against a web service by a busy Condor system. This cache approach also decreases the latency for condor_* command line calls and ensures a Condor pool can survive an outage of all of the configuration-publishing resources.

Support for multiple URLs provides a simple mechanism to ensure high-availability for configuration information. The cache_config tool will attempt to pull configuration from each URL, stopping after the first successful pull happens.

cache_config checks for an existing, local, cache file to determine whether the time-to-live (TTL) has expired. If the cache file's time to live has not expires, cache_config simply outputs the local, cache file contents. If the time to live for the cached file has expired, a cross-platform compatible lock is acquired, with its own TTL to avoid deadlock cases. cache_config then gets the configuration file by attempting to read from the list of URLs for the configuration data. If any error occurs in reading from the first URL, the second is attempted, then the third, and so on, until configuration is successfully fetched and cached. Should all URLs fail, cache_config returns the existing, stale, configuration with additional configuration settings embedded in the output that publish the details of the failures.

• CacheFile - The file name for the cached config on local disk
• CacheTTL - The time-to-live for the cache file
• LockTTL - The time-to-live for the file lock
• URL1 - The first URL to check
• [URL2 …] - Additional, optional failover URLs to check

In using cache_config with Condor it is recommended you copy it to your condor\bin directory (the BIN directory in your current Condor configuration). When configuring Condor, it is recommended you have a local configuration file that will get Condor up and running, then use the following line within that file to fetch the detailed configuration for the machine:

LOCAL_CONFIG_FILE = "$(BIN)\cache_config.py $(LOCAL)\cached_config 30 30 http://webserver_url" |

CycleServer stores associations between machines and configuration templates for easy machine-configuration management and serves up these configuration files up via a URL with a regular syntax. It has logic for choosing a default configuration template if a new, never-before-seen host requests configuration information.

To fetch your configuration from a CycleServer instance, make your configuration line:

LOCAL_CONFIG_FILE = "$(BIN)\cache_config.py $(LOCAL)\cached_config 30 30 http://cycleserver_host:cycleserver_port/condor/assigned_template/$(FULL_HOSTNAME)" |

For more information on "Configuration with Pipes" in Condor, please see the Condor manual. In the 7.6 the appropriate section is 3.3.1.4: http://www.cs.wisc.edu/condor/manual/v7.6/3_3Configuration.html#15120

Copyright (C) 2007-2011, Cycle Computing, LLC.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

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