cdist/doc/man/to_check/cdist-type.text

cdist-type(7)
==============
Nico Schottelius <nico-cdist--@--schottelius.org>


NAME
----
cdist-type - Functionality bundled


SYNOPSIS
--------
Other languages name this module or class 


DESCRIPTION
-----------
Types are the main component of cdist and define functionality. If you
use cdist, you'll write a type for every functionality you would like
to use.



Was man mit cdist type machen kann.....

A cdist type describes some kind of functionality, starting from simple stuff
like copying files until complex user auth/ldap/ kerberos infrastructure
designs. The name of every type is prefixed with two underscores (__) by convention.


, because
types will be executed and the two underscores prevent collisions with real
binaries (like "file").
In general, types should be written independent of hosts (as in reusable
code), but may be used implement functionality only needed on one host
as well.
It must be assumed that the clients are pretty dumb and thus do not have high
level tools like ruby installed. If a type requires specific tools to be present
on the target, there must be another type that provides this tool and the first
type must create an object of the specific type.
If the generated code fails on the client, it must print diagnostistic messages on
stderr and exit non-zero, so the configuration is aborted.
Types may make use of other types to realise a new type or may implement some
functionality on their own.

Types may consist of 
- a number of required and optional parameters they accept,
- a manifest script that makes use of the parameters and may create other objects
- explorers that explore type specific information on the target
- a gencode script, that may generate code to be executed on the target

Every time a type is used, a new object is created of the specific type,
with a type specific unique id that stores the parameters


HOW TO USE A TYPE
-----------------
You can use types from the initial manifest or the type manifest like a
normal command:

--------------------------------------------------------------------------------
# Creates empty file /etc/cdist-configured
__file /etc/cdist-configured --type file

# Ensure tree is installed
__package tree --state installed
--------------------------------------------------------------------------------

Internally cdist-type-emulator(1) will be called from cdist-manifest-run(1) to
save the given parameters into a cconfig database, so they can be accessed by
the manifest and gencode scripts of the type (see below).


HOW TO WRITE A NEW TYPE
-----------------------
A type consists of

- parameter (optional)
- manifest  (optional)
- gencode   (optional)
- explorer  (optional)

Types are stored below conf/type/. Their name should always be prefixed with
two underscores (__) to prevent collisions with other binaries in $PATH.

To begin a new type from a template, execute "cdist-type-template __NAME"
and cd conf/type/__NAME.


DEFINING PARAMETERS
-------------------
Every type consists of optional and required parameters, which must
be created in a newline seperated file in parameters/required and
parameters/optional. If either or both missing, the type will have
no required, no optional or no parameters at all.

Example:
--------------------------------------------------------------------------------
echo servername >> conf/type/__nginx_vhost/parameter/required
echo logdirectory >> conf/type/__nginx_vhost/parameter/optional
--------------------------------------------------------------------------------


WRITING THE MANIFEST
--------------------
In the manifest of a type you can use other types, so your type extends
their functionality. A good example is the __package type, which in
a shortened version looks like this:

--------------------------------------------------------------------------------
os="$(cat "$__global/explorer/os")"
case "$os" in
      archlinux) type="pacman" ;;
      debian|ubuntu) type="apt" ;;
      gentoo) type="emerge" ;;
      *)
         echo "Don't know how to manage packages on: $os" >&2
         exit 1
      ;;
esac

__package_$type "$@"
--------------------------------------------------------------------------------

As you can see, the type can reference different environment variables,
which are documented in cdist-environment-variables(7).

Always ensure the manifest is executable, otherwise cdist will not be able
to execute it.

WRITING THE GENCODE SCRIPT
--------------------------

HOW TO INCLUDE A TYPE INTO UPSTREAM CDIST
-----------------------------------------
If you think your type may be useful for others, ensure it works with the
current master branch of cdist and submit the git url containing the type for
inclusion to the mailinglist **cdist at cdist -- at -- l.schottelius.org**.

Ensure there is a corresponding manpage named cdist-type-NAME (without
underscores) included.


SEE ALSO
--------
- cdist-manifest-run(1)


COPYING
-------
Copyright \(C) 2010-2011 Nico Schottelius. Free use of this software is
granted under the terms of the GNU General Public License version 3 (GPLv3).