Config::Model::Cookbook::CreateModelFromDoc(3pm)	User Contributed Perl Documentation	  Config::Model::Cookbook::CreateModelFromDoc(3pm)

NAME

       Config::Model::Cookbook::CreateModelFromDoc - Create a configuration model from application documentation

VERSION

       version 2.021

Introduction
       This page shows step by step how was created "Popcon"'s model from "Popcon" documentation provided as comments in "Popcon"'s sample
       configuration file.

"Popcon" configuration file
       A quick looks in "/etc" directory shows that "Popcon"'s configuration is stored in "/etc/popularity-contest.conf</t":

	# Config file for Debian's popularity-contest package.
	#
	# To change this file, use:
	#	 dpkg-reconfigure popularity-contest
	#
	# You can also edit it by hand, if you so choose.
	#
	# See /usr/share/popularity-contest/default.conf for more info
	# on the options.

	MY_HOSTID="172921501FFFFFAAAA6897etc"
	PARTICIPATE="yes"
	USEHTTP="yes"
	DAY="5"

       The important part is the mention of "default.conf" which contains all the required information to create "Popcon"'s configuration model.

"Popcon" documentation
       Let's start from "default.conf" file. Since this file is loaded by "popcon" before loading "/etc/popularity-contest.conf</t", all values
       there can be used as application default values (aka upstream_default):

	# Default config file for Debian's popularity-contest package.
	#
	# Local overrides are in /etc/popularity-contest.conf

	# PARTICIPATE can be one of "yes" or "no".
	# If you don't want to participate in the contest, say "no"
	# and we won't send messages.
	#
	# If this option is missing, the default is "no".
	#
	PARTICIPATE="no"

	# MAILTO specifies the address to e-mail statistics to each week.
	#
	MAILTO="survey@popcon.debian.org"

	# MAILFROM is the forged sender email address you want to use in
	# email submitted to the popularity-contest.  If this is commented
	# out, no From: or Sender: lines will be added to the outgoing mail,
	# and it will be your MTA's job to add them.  This is usually what
	# you want.
	#
	# If your MTA is misconfigured or impossible to configure correctly,
	# and it always generates invalid From: and/or Sender: lines, you
	# can force different results by setting MAILFROM here.  This can
	# cause problems with spam bouncers, so most people should leave it
	# commented out.
	#
	#MAILFROM="root@example.org"

	# SUBMITURLS is a space separated list of where to submit
	# popularity-contest reports using http.
	SUBMITURLS="http://popcon.debian.org/cgi-bin/popcon.cgi"

	# USEHTTP enables http reporting.   Set this to 'yes' to enable it.
	USEHTTP="yes"

	# HTTP_PROXY allows one to specify an HTTP proxy server, the syntax is
	# HTTP_PROXY="http://proxy:port". This overrides the environment
	# variable http_proxy.

	# MY_HOSTID is a secret number that the popularity-contest receiver
	# uses to keep track of your submissions.  Whenever you send in a
	# new entry, it overwrites the last one that had the same HOSTID.
	#
	# This key was generated automatically so you should normally just
	# leave it alone.
	#
	#MY_HOSTID="_ID_"

       This file contains everything we need:

       o   Parameter names

       o   Documentation

       o   Default values

       Now, we will use our favorite editor to edit this file and add YAML tags that can be understood by "config-model-edit"

Creating the YAML skeleton
       "config-model-edit" is able to load a model described in YAML. To do this the above file needs to be translated in YAML. That's not as
       complicated as it may sound.

       First, a YAML file must begin with ---. Then the class must be declared:

	---
	class:
	  PopCon:

       Note that, like with Python language, the indentation is important to define the structure of the file. Here, the "PopCon" class is
       followed by a ':' as it defines a new hierarchical level to describes the configuration elements of this class:

	    element:

       Now we can deal with the configuration parameters. Let's detail the "PARTICIPATE" element. Here's the spec in from "default.conf":

	# PARTICIPATE can be one of "yes" or "no".
	# If you don't want to participate in the contest, say "no"
	# and we won't send messages.
	#
	# If this option is missing, the default is "no".
	#
	PARTICIPATE="no"

       In the YAML file, the comments are moved in the "description" field and the value in the file is used as upstream default:

	     PARTICIPATE:
	       upstream_default: no
	       description: >
		If you don't want to participate in the contest,
		say "no" and we won't send messages.

       Likewise for the remaining parameters:

	     MAILTO:
	       description: >
		specifies the address to e-mail statistics to each week.
	       default: 'survey@popcon.debian.org'
	     MAILFROM:
	       description: >-
		MAILFROM is the forged sender email address you want to use
		in email submitted to the popularity-contest.  If this is
		commented out, no From: or Sender: lines will be added to the
		outgoing mail, and it will be your MTA's job to add them.  This
		is usually what you want.

		If your MTA is misconfigured or
		impossible to configure correctly, and it always generates
		invalid From: and/or Sender: lines, you can force different
		results by setting MAILFROM here.  This can cause problems with
		spam bouncers, so most people should leave it commented out.

       In the description above, the "chimping" marker '-' after '>' is used to keep paragraph formatting in the help.

	     SUBMITURLS:
	       description: >
		Space separated list of where to submit popularity-contest
		reports using http.
	       default: >
		http://popcon.debian.org/cgi-bin/popcon.cgi

	     USEHTTP:
	       description: >
		enables http reporting.   Set this to 'yes' to enable it.
	       default: "yes"

	     HTTP_PROXY:
	       description: >
		allows one to specify an HTTP proxy server, the syntax is
		"http://proxy:port". This overrides the environment variable
		http_proxy.

	     MY_HOSTID:
	       description: >
		secret number that the popularity-contest receiver uses to
		keep track of your submissions.  Whenever you send in a new
		entry, it overwrites the last one that had the same HOSTID.

		This key was generated automatically so you should normally
		just leave it alone.

Loading the YAML skeleton
       Now that the YAML file was created, you can turn it into a model and load it in the model editor GUI with the following command:

	config-model-edit -model PopCon -load_yaml popcon.yml -force

       Note that the model is incomplete: some mandatory parameters are missing from the YAML file so the -force option must be used. These
       missing parameters are also flagged with a red cross in the GUI.

Completing missing model parts
       To complete the model, the easiest way is to run the wizard to complete the missing values. In the GUI, you can use the menu "File ->
       wizard" to launch the wizard.  Then click on the 'OK' button in the new window.

       The wizard will first stop on the parameter list (not because there's an error, but because the parameter list is flagged as important)

       There, you can re-order the parameters by selecting one and clicking on one of the blue arrows to move it up or down. Once you're
       satisfied, click on Next.

       The widget will now stop on the first missing information. Just select the correct type ('leaf' here), click 'store' and 'Next'.

       You can repeat these steps until the wizard exits.

Specifying read and write backend
       Once the model is complete, it's time to specify how to read and write the file. In "Popcon" class specification:

       o   right-click on read_config

       o   click on push new node to create a new read specification

       o   right-click on the created item (shown at index "0")

       You will get a window showing you the parameters to fill to specify the read backend.

       Now fill the blank on the right side. The backend to use is "ShellVar" since popularity-contest.conf is made of shell variables.

       Since the write specification is identical, there's no need to specify it. Config::Model will do the right thing.

Testing the model
       You can test the model by clicking on menu "Test -> Model". You will be shown the "Popcon" configuration editor GUI. The same that your
       users will get.

       If everything is fine, you can quit the model editor (menu File->quit)

The resulting model
       The model you have just created is stored in "lib/Config/Model/models/Popcon.pl".

       You can test directly this model with :

	 config-edit -dev -model Popcon

Feedback welcome
       Feel free to send comments and suggestion about this page at

	config-model-users at lists dot sourceforge dot net.

AUTHORS

       Dominique Dumont <ddumont at cpan.org>

perl v5.14.2							    2012-11-09			  Config::Model::Cookbook::CreateModelFromDoc(3pm)