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VCAP Package Cache ================== Purpose: The package cache keeps a local pre-built copy of packages (such as ruby gems, python packages, etc.) so that they do not need to be repeatedly downloaded and built during application staging. Operation: ---------- -the package cache starts up a stand-alone server that waits for requests to load packages, implementing a simple rest interface (see server.rb). -once a request is recieved, the source package is fetched either by downloading it (if it is remote), or copying it from the inbox directory (if it is local). -once fetched, the source package is built in a sandboxed context, and the resulting built contents are archived and stored in the cache. -the name of the built package in the cache is a function of where it came from, remote packages are stored by their cannonical name plus a .tgz extension e.g. thin (1.2.11) would be stored as thin-1.2.11.tgz in the cache. -local packages are stored by the SHA1 hash of their contents plus a .tgz extension. Security model: --------------- -clients of the cache are assumed to be untrusted. -clients access the cache directly through the file system. clients can access cache contents, but not list them. consequently - to access a package a client must know either the content of the source package(for local packages) or the cannonical name (for remote packages). -to hand a local source package to the package_cache, it is copied into the inbox directory. the inbox security model is described in detail in (inbox.rb) *Directory structure all directories used by the package_cache are relative to a base directory, /var/vcap.local/package_cache, by default. vcap.local/package_cache/cache - is the location of cached package for use. vcap.local/package_cache/builds - is the temporary directory where packages are built. vcap.local/package_cache/inbox - is the 'inbox' where the client places 'vendored' packages to be added to the cache i.e. un-built packages it already has stored locally. Using and testing the cache. ------------------------------ The package cache must currently be run as root, it can be started using the following command. /vcap/package_cache]rvmsudo ./bin/package_cache A full working example that exercises all features of the client can be found in -- the package cache client is found in client.rb in the main source repository. vcap/package_cache/spec/functional/e2e_test A simple load tester can be found in. vcap/package_cache/spec/functional/load_test invoking it without arguments will display the usage message.