NAME

       cdist-messaging - How the initial manifest and types can communication

DESCRIPTION

       cdist has a simple but powerful way of allowing communication between the initial manifest
       and types as well as types and types.

       Whenever execution is passed from cdist to one of the scripts described below, cdist
       generate 2 new temporary files and exports the environment variables messages_in and
       messages_out to point to them.

       Before handing over the control, the content of the global message file is copied into the
       file referenced by $__messages_in.

       After cdist gained control back, the content of the file referenced by $__messages_out is
       appended to the global message file.

       This way overwriting any of the two files by accident does not interfere with other types.

       The order of execution is not defined unless you create dependencies between the different
       objects (see cdist-manifest(7)) and thus you can only react reliably on messages by
       objects that you depend on.

AVAILABILITY

       Messaging is possible between all local scripts:

       •   initial manifest

       •   type/manifest

       •   type/gencode-local

       •   type/gencode-remote

EXAMPLES

       When you want to emit a message use:

           echo "something" >> "$__messages_out"

       When you want to react on a message use:

           if grep -q "^__your_type/object/id:something" "$__messages_in"; then
               echo "I do something else"
           fi

SEE ALSO

       •   cdist(1)

       •   cdist-manifest(7)

       •   cdist-reference(7)

       •   cdist-type(7)

COPYING

       Copyright (C) 2013 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-MESSAGING(7)