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

NAME

       cdist-manifest - (Re-)Use types

DESCRIPTION

       Manifests are used to define which objects to create. Objects are instances of types, like
       in object oriented programming languages. An object is represented by the combination of
       type + slash + object name: __file/etc/cdist-configured is an object of the type __file
       with the name etc/cdist-configured.

       All available types can be found in the cdist/conf/type/ directory, use ls cdist/conf/type
       to get the list of available types. If you have setup the MANPATH correctly, you can use
       man cdist-reference to access the reference with pointers to the manpages.

       Types in manifests are used like normal command line tools. Let’s have a look at an
       example:

           # Create object of type __package with the parameter state = absent
           __package apache2 --state absent

           # Same with the __directory type
           __directory /tmp/cdist --state present

       These two lines create objects, which will later be used to realise the configuration on
       the target host.

       Manifests are executed locally as a shell script using /bin/sh -e. The resulting objects
       are stored in an internal database.

       The same object can be redefined in multiple different manifests as long as the parameters
       are exactly the same.

       In general, manifests are used to define which types are used depending on given
       conditions.

INITIAL AND TYPE MANIFESTS

       Cdist knows about two types of manifests: The initial manifest and type manifests. The
       initial manifest is used to define, which configurations to apply to which hosts. The type
       manifests are used to create objects from types. More about manifests in types can be
       found in cdist-type(7).

DEFINE STATE IN THE INITIAL MANIFEST

       The initial manifest is the entry point for cdist to find out, which objects to configure
       on the selected host. Cdist expects the initial manifest at cdist/conf/manifest/init.

       Within this initial manifest you define, which objects should be created on which host. To
       distinguish between hosts, you can use the environment variable __target_host. Let’s have
       a look at a simple example:

           __cdistmarker

           case "$__target_host" in
              localhost)
                   __directory /home/services/kvm-vm --parents yes
              ;;
           esac

       This manifest says: Independent of the host, always use the type __cdistmarker, which
       creates the file /etc/cdist-configured, with the timestamp as content. The directory
       /home/services/kvm-vm, including all parent directories, is only created on the host
       localhost.

       As you can see, there is no magic involved, the manifest is simple shell code that
       utilises cdist types. Every available type can be executed like a normal command.

SPLITTING UP THE INITIAL MANIFEST

       If you want to split up your initial manifest, you can create other shell scripts in
       cdist/conf/manifest/ and include them in cdist/conf/manifest/init. Cdist provides the
       environment variable __manifest to reference the directory containing the initial manifest
       (see cdist-reference(7)).

       The following example would include every file with a .sh suffix:

           # Include *.sh
           for manifest in $__manifest/*.sh; do
               # And source scripts into our shell environment
               . "$manifest"
           done

DEPENDENCIES

       If you want to describe that something requires something else, just setup the variable
       "require" to contain the requirements. Multiple requirements can be added white space
       separated.

            1 # No dependency
            2 __file /etc/cdist-configured
            3
            4 # Require above object
            5 require="__file/etc/cdist-configured" __link /tmp/cdist-testfile \
            6    --source /etc/cdist-configured  --type symbolic
            7
            8 # Require two objects
            9 require="__file/etc/cdist-configured __link/tmp/cdist-testfile" \
           10    __file /tmp/cdist-another-testfile

       Above the "require" variable is only set for the command that is immediately following it.
       Dependencies should always be declared that way.

       On line 4 you can see that the instantion of a type "link" object needs the object
       "file/etc/cdist-configured" to be present, before it can proceed.

       This also means that the "link" command must make sure, that either
       "file/etc/cdist-configured" allready is present, or, if it’s not, it needs to be created.
       The task of cdist is to make sure, that the dependency will be resolved appropriately and
       thus "file/etc/cdist-configured" be created if necessary before "link" proceeds (or to
       abort execution with an error).

       All objects that are created in a type manifest are automatically required from the type
       that is calling them. This is called "autorequirement" in cdist jargon.

       You can find an more in depth description of the flow execution of manifests in
       cdist-stages(7) and of how types work in cdist-type(7).

CREATE DEPENDENCIES FROM EXECUTION ORDER

       You can tell cdist to execute all types in the order in which they are created in the
       manifest by setting up the variable CDIST_ORDER_DEPENDENCY. When cdist sees that this
       variable is setup, the current created object automatically depends on the previously
       created object.

       It essentially helps you to build up blocks of code that build upon each other (like first
       creating the directory xyz than the file below the directory).

OVERRIDES

       In some special cases, you would like to create an already defined object with different
       parameters. In normal situations this leads to an error in cdist. If you wish, you can
       setup the environment variable CDIST_OVERRIDE (any value or even empty is ok) to tell
       cdist, that this object override is wanted and should be accepted. ATTENTION: Only use
       this feature if you are 100% sure in which order cdist encounters the affected objects,
       otherwise this results in an undefined situation.

       If CDIST_OVERRIDE and CDIST_ORDER_DEPENDENCY are set for an object, CDIST_ORDER_DEPENDENCY
       will be ignored, because adding a dependency in case of overrides would result in circular
       dependencies, which is an error.

EXAMPLES

       The initial manifest may for instance contain the following code:

           # Always create this file, so other sysadmins know cdist is used.
           __file /etc/cdist-configured

           case "$__target_host" in
              my.server.name)
                 __directory /root/bin/
                 __file /etc/issue.net --source "$__manifest/issue.net
              ;;
           esac

       The manifest of the type "nologin" may look like this:

           __file /etc/nologin --source "$__type/files/default.nologin"

       This example makes use of dependencies:

           # Ensure that lighttpd is installed
           __package lighttpd --state present
           # Ensure that munin makes use of lighttpd instead of the default webserver
           # package as decided by the package manager
           require="__package/lighttpd" __package munin --state present

       How to override objects:

           # for example in the inital manifest

           # create user account foobar with some hash for password
           __user foobar --password 'some_fancy_hash' --home /home/foobarexample

           # ... many statements and includes in the manifest later ...
           # somewhere in a conditionally sourced manifest
           # (e.g. for example only sourced if a special application is on the target host)

           # this leads to an error ...
           __user foobar --password 'some_other_hash'

           # this tells cdist, that you know that this is an override and should be accepted
           CDIST_OVERRIDE=yes __user foobar --password 'some_other_hash'
           # it's only an override, means the parameter --home is not touched
           # and stays at the original value of /home/foobarexample

       Dependencies defined by execution order work as following:

           # Tells cdist to execute all types in the order in which they are created ...
           export CDIST_ORDER_DEPENDENCY=on
           __sample_type 1
           require="__some_type_somewhere/id" __sample_type 2
           __example_type 23
           # Now this types are executed in the creation order until the variable is unset
           unset CDIST_ORDER_DEPENDENCY
           # all now following types cdist makes the order ..
           __not_in_order_type 42

           # how it works :
           # this lines above are translated to:
           __sample_type 1
           require="__some_type_somewhere/id __sample_type/1" __sample_type 2
           require="__sample_type/2" __example_type 23
           __not_in_order_type 42

SEE ALSO

       ·   cdist-tutorial(7)

       ·   cdist-type(7)

COPYING

       Copyright (C) 2010-2014 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-MANIFEST(7)