Provided by: cdist_4.0.0~pre3-2_all bug

NAME

       cdist-type - Functionality bundled

SYNOPSIS

       __TYPE ID --parameter value [--parameter value ...]

       __TYPE --parameter value [--parameter value ...] (for singletons)

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.

HOW TO USE A TYPE

       You can use types from the initial manifest or the type manifest like a normal shell
       command:

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

           # Ensure tree is installed
           __package tree --state installed

       A list of supported types can be found in the cdist-reference(7) manpage.

SINGLETON TYPES

       If a type is flagged as a singleton, it may be used only once per host. This is useful for
       types which can be used only once on a system. Singleton types do not take an object name
       as argument.

       Example:

           # __issue type manages /etc/issue
           __issue

           # Probably your own type - singletons may use parameters
           __myfancysingleton --colour green

HOW TO WRITE A NEW TYPE

       A type consists of

       ·   parameter (optional)

       ·   manifest (optional)

       ·   singleton (optional)

       ·   explorer (optional)

       ·   gencode (optional)

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

       To implement a new type, create the directory cdist/conf/type/__NAME.

DEFINING PARAMETERS

       Every type consists of required, optional and boolean parameters, which must each be
       declared in a newline separated file in parameter/required, parameter/required_multiple,
       parameter/optional, parameter/optional_multiple and parameter/boolean. Parameters which
       are allowed multiple times should be listed in required_multiple or optional_multiple
       respectively. All other parameters follow the standard unix behaviour "the last given
       wins". If either is missing, the type will have no required, no optional, no boolean or no
       parameters at all.

       Default values for optional parameters can be predefined in parameter/default/<name>.

       Example:

           echo servername >> cdist/conf/type/__nginx_vhost/parameter/required
           echo logdirectory >> cdist/conf/type/__nginx_vhost/parameter/optional
           echo loglevel >> cdist/conf/type/__nginx_vhost/parameter/optional
           mkdir cdist/conf/type/__nginx_vhost/parameter/default
           echo warning > cdist/conf/type/__nginx_vhost/parameter/default/loglevel
           echo server_alias >> cdist/conf/type/__nginx_vhost/parameter/optional_multiple
           echo use_ssl >> cdist/conf/type/__nginx_vhost/parameter/boolean

USING PARAMETERS

       The parameters given to a type can be accessed and used in all type scripts (e.g manifest,
       gencode-, explorer/). Note that boolean parameters are represented by file existence. File
       exists → True, file does not exist → False

       Example: (e.g. in cdist/conf/type/__nginx_vhost/manifest)

           # required parameter
           servername="$(cat "$__object/parameter/servername")"

           # optional parameter
           if [ -f "$__object/parameter/logdirectory" ]; then
              logdirectory="$(cat "$__object/parameter/logdirectory")"
           fi

           # optional parameter with predefined default
           loglevel="$(cat "$__object/parameter/loglevel")"

           # boolean parameter
           if [ -f "$__object/parameter/use_ssl" ]; then
              # file exists -> True
              # do some fancy ssl stuff
           fi

           # parameter with multiple values
           if [ -f "$__object/parameter/server_alias" ]; then
              for alias in $(cat "$__object/parameter/server_alias"); do
                 echo $alias > /some/where/usefull
              done
           fi

INPUT FROM STDIN

       Every type can access what has been written on stdin when it has been called. The result
       is saved into the stdin file in the object directory.

       Example use of a type: (e.g. in cdist/conf/type/__archlinux_hostname)

           __file /etc/rc.conf --source - << eof
           ...
           HOSTNAME="$__target_host"
           ...
           eof

       If you have not seen this syntax (<< eof) before, it may help you to read about "here
       documents".

       In the __file type, stdin is used as source for the file, if - is used for source:

               if [ -f "$__object/parameter/source" ]; then
                   source="$(cat "$__object/parameter/source")"
                   if [ "$source" = "-" ]; then
                       source="$__object/stdin"
                   fi
               ....

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-reference(7).

       Always ensure the manifest is executable, otherwise cdist will not be able to execute it.
       For more information about manifests see cdist-manifest(7).

SINGLETON - ONE INSTANCE ONLY

       If you want to ensure that a type can only be used once per target, you can mark it as a
       singleton: Just create the (empty) file "singleton" in your type directory:

           touch cdist/conf/type/__NAME/singleton

       This will also change the way your type must be called:

           __YOURTYPE --parameter value

       As you can see, the object ID is omitted, because it does not make any sense, if your type
       can be used only once.

THE TYPE EXPLORERS

       If a type needs to explore specific details, it can provide type specific explorers, which
       will be executed on the target for every created object.

       The explorers are stored under the "explorer" directory below the type. It could for
       instance contain code to check the md5sum of a file on the client, like this (shortened
       version from the type __file):

           if [ -f "$__object/parameter/destination" ]; then
              destination="$(cat "$__object/parameter/destination")"
           else
              destination="/$__object_id"
           fi

           if [ -e "$destination" ]; then
              md5sum < "$destination"
           fi

WRITING THE GENCODE SCRIPT

       There are two gencode scripts: gencode-local and gencode-remote. The output of
       gencode-local is executed locally, whereas the output of gencode-remote is executed on the
       target. The gencode scripts can make use of the parameters, the global explorers and the
       type specific explorers.

       If the gencode scripts encounters an error, it should print diagnostic messages to stderr
       and exit non-zero. If you need to debug the gencode script, you can write to stderr:

           # Debug output to stderr
           echo "My fancy debug line" >&2

           # Output to be saved by cdist for execution on the target
           echo "touch /etc/cdist-configured"

VARIABLE ACCESS FROM THE GENERATED SCRIPTS

       In the generated scripts, you have access to the following cdist variables

       ·   __object

       ·   __object_id

       but only for read operations, means there is no back copy of this files after the script
       execution.

       So when you generate a script with the following content, it will work:

           if [ -f "$__object/parameter/name" ]; then
              name="$(cat "$__object/parameter/name")"
           else
              name="$__object_id"
           fi

HINTS FOR TYPEWRITERS

       It must be assumed that the target is pretty dumb and thus does 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 should create an object of
       the specific type.

       If your type wants to save temporary data, that may be used by other types later on (for
       instance file), you can save them in the subdirectory "files" below $object (but you must
       create it yourself). cdist will not touch this directory.

       If your type contains static files, it’s also recommended to place them in a folder named
       "files" within the type (again, because cdist guarantees to never ever touch this folder).

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 have a look at cdist-hacker(7) on how to submit it.

SEE ALSO

       ·   cdist-explorer(7)

       ·   cdist-hacker(7)

       ·   cdist-stages(7)

       ·   cdist-tutorial(7)

COPYING

       Copyright (C) 2011-2012 Nico Schottelius. Free use of this software is granted under the
       terms of the GNU General Public License version 3 (GPLv3).

AUTHOR

       Nico Schottelius <nico-cdist--@--schottelius.org>
           Author.

                                            04/07/2016                              CDIST-TYPE(7)