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Bcfg2 Client Code Refactoring
This page reflects a completed project. It has been merged into trunk and was the basis for the 0.8.5 release.
This branch is for work in decomposing the platform-specific client modules into service/packaging system-specific modules; the platform-specific modules will then just import the service/packaging system-specific modules they require (e.g. Redhat.py would import rpm.py and chkconfig.py, all the platforms will import encap.py, etc.)
A mailing list thread with more discussion of this is here:
Ticket #73 describes some aspects of this issue.
NLD's 5-Step Plan
- create classes in Bcfg2.Client.Tools that defines an API for all tools (Implemented as Bcfg2.Client.Tools.Tool, Bcfg2.Client.Tools.PkgTool, and Bcfg2.Client.SvcTool). All Tools will subclass one of these (Bcfg2.Client.Tools.RPM, Bcfg2.Client.Tools.SMF, etc) [DONE]
- build a set of error types that can be raised during tool instantiation and operation [DONE]
- Implement a tool class for each underlying tool. (see table below for status)
- modify the Bcfg2.Client.Frame code to figure out what methods to call tools for entry verification, installation and removal.
- is things like schema updates and metadata code updates
Implementation Status
This work was happening at:
https://svn.mcs.anl.gov/repos/bcfg/branches/refactor/client
It has since been completed and merged into trunk.
Bcfg2.Client.Frame is completely finished. It redirects calls to lower-level tool modules. It also provides a unified view across all tools.
| Tool | Status | Who | Tested? |
| RPM | done | NLD | Yes |
| POSIX | done | NLD | Yes |
| Encap | done | DC | No |
| SYSV | done | NLD | Yes |
| Pkg-get (Blastwave) | done | NLD | No |
| APT | done | NLD | Yes |
| ChkConfig? | done | NLD | Yes |
| SMF | done | NLD | Yes |
| PostInstall? | done | NLD | Yes |
| DebInit? | done | NLD | Yes |
| launchd | done | JH | Yes |
All currently supported tools are now implemented. For tools which may be added in the future, see FeatureClient?.
Test Plan
- Get verification working (done)
- Get stats gathering and upload working (done)
- Find and complain about unhandled config entries (done)
- Verify results against the old client (done on debian, must be done for redhat and solaris)
- Build small test sets to test install set
Design Notes
Bcfg2.Client.Frame redirects calls to underlying tools. Its methods are:
- Inventory - Compare client state to configuration specification
- Install - Install wrong entries (sparsely, if specified)
- FindExtra - Locate extra entries using tool-specific heuristics
- Query - get user input of which entries should be modified
- Remove - remove specified extra entries
Tool methods:
- Verify<entry.tag> - verify entry state. Must return True/False?
- Install<entry.tag> - install entry. Must return True/False?
- Install (optional) - bulk install method for entries
- FindExtra - locate extra entries
Writing a Client Tool Module
See WritingClientToolDrivers for details.
