Dorrie

So after abandoning my misadventures of last week, I decided to clone the Dorrie project, and use that as the underlying base for the remixerator. The bread and butter of this project is in the pykickstart.parser module, which has many tools to parsing and generating a working kickstart file. I will briefly explain the key functions and objects that are used in dorrie.

pykickstart.parser defines three classes:
KickstartParser - a state machine used when going through a kickstart
Packages - an object that encapsulates all the selected (and removed) packages of the kickstart.
Script - an object that encapsulates a script of the kickstart file.



The KickstartParser's most useful function for us is the readKickstart() function. This, given a kickstart file, will go through (using the state machine internally) and create all the objects necessary to represent a particular kickstart. This uses internal parsing and handling functions. It also has an internal handler object that saves and executes commands that are parsed.

The Packages object has four important lists. The lists excludedList and packageList, that contain the actual packages for the kickstart (the former being denoted with a '-' character). The lists groupList and excludedGroupList are also included in this module. Essentially, when we want to add or remove any particular package, we add the package name to the respective lists.

The Script module has two important fields: script and type. Each script object should encapsulate only one script, the script field set to the actual script's string, and the type set to the relevant type found in pykickstart.constants. Creating a script object is not difficult, however, adding it in, is. Pykickstart has a BaseHandler object (to which KickstartParser's handler object is a subclass), that contains a scripts section, holding these instances of the script object.

One of the difficulties in using the dorrie project for the remixerator is that adding a post script is non-trivial. The documentation states that to add a script, you call KickstartParser.addScript... but this function actually doesn't exist. For the time being, one way to get around this is to literally append %post script to the returned formatted string. I did this for the sake of time, but this will be changed when I can find a more proper way to add a script object.

After this, I had to go through Dorrie's settings.py file and change references to reflect fedora 16. This included versions of the internal parser (these are defined in the latest pykickstart repository), and package trees.

Next is a little bit of de-chroming, to get the aesthetics looking like an RIT project.

Edit: Scripts get added when the Script "section" object has its finalize method called. I'll post more on this later.