cdist/bin/cdist-quickstart

#!/bin/sh
#
# 2010-2011 Nico Schottelius (nico-cdist at schottelius.org)
#
# This file is part of cdist.
#
# cdist is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# cdist is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with cdist. If not, see <http://www.gnu.org/licenses/>.
#
#
# Give the user an introduction into cdist
#

. cdist-config
set -eu

banner="cdist-quickstart>"
continue="Press enter to continue or ctrl-c to abort."
create_continue="Press enter to create the described files/directories"

__prompt()
{
   echo -n "$banner" "$@"
   read answer
}

################################################################################
# Intro of quickstart
#
cat << eof
$banner cdist version $__cdist_version

Welcome to the interactive guide to cdist!
This is the interactive tutorial and beginners help for cdist and here's
our schedule:

   - Stages:   How cdist operates
   - Explorer: Explore facts of the target host
   - Manifest: Map configurations to hosts
   - Types:    Bundled functionality
   - Deploy a configuration to the local host!

eof
__prompt "$continue"

################################################################################
# Stages
#
cat << eof

To deploy configurations to a host, you call

   cdist-deploy-to <hostname>

which makes calls to other scripts, which realise the so called "stages".
Usually you'll not notice this, but in case you want to debug or hack cdist,
you can run each stage on its own. Besides that, you just need to remember
that the command cdist-deploy-to is the main cdist command.

See also:

   Source of cdist-deploy-to, cdist-stages(7)

eof
__prompt "$continue"

################################################################################
# Explorer
#
cat << eof

The first thing cdist always does is running different explorers on the
target host. The explorers can be found in the directory

   ${__cdist_explorer_dir}

An explorer is executed on the target host and its output is saved to a file.
You can use these files later to decide what or how to configure the host.

For a demonstration, we'll call the OS explorer locally now, but remember:
This is only for demonstration, normally it is run on the target host.
The os explorer will which either displays the detected operating system or
nothing if it does not know your OS.

See also:

   cdist-explorer(7)

eof
explorer="${__cdist_explorer_dir}/os"

__prompt "Press enter to execute $explorer"

set -x
"$explorer"
set +x

################################################################################
# Manifest
#
cat << eof

The initial manifest is the entry point for cdist to find out, what you would
like to have configured. It is located at

   ${__cdist_manifest_init}

And can be as simple as

--------------------------------------------------------------------------------
__file /etc/cdist-configured --type file
--------------------------------------------------------------------------------

See also:

   cdist-manifest(7)

eof
__prompt "$continue"

cat << eof

Let's take a deeper look at the initial manifest to understand what it means:

   __file /etc/cdist-configured --type file
      |     |                    |        \\
      |     |        The parameter type    \\ With the value file
      |     |
      |     |
      |     | This is the object id
      |
   __file is a so called "type"


This essentially looks like a standard command executed in the shell.
eof
__prompt "$continue"

cat << eof

And that's exactly true. Manifests are shell snippets that can use
types as commands with arguments. cdist prepends a special path
that contain links to the cdist-type-emulator, to \$PATH, so you
can use your types as a command.

This is also the reason why types should always be prefixed with
"__", to prevent collisions with existing binaries.

The object id is unique per type and used to prevent you from creating
the same object twice.

Parameters are type specific and are always specified as --parameter <value>.

See also:

   cdist-type-build-emulation(1), cdist-type-emulator(1)

eof
__prompt "$continue"

################################################################################
# Types
#
cat << eof

Types are bundled functionality and are the main component of cdist.
If you want to have a feature x, you write the type __x. Types are stored in

   ${__cdist_type_dir}

And cdist ships with some types already!

See also:

   cdist-type(7)

eof
__prompt "Press enter to see available types"

set -x
ls ${__cdist_type_dir}
set +x

cat << eof

Types consist of the following parts:

   - ${__cdist_name_parameter} (${__cdist_name_parameter_required}/${__cdist_name_parameter_optional}
   - ${__cdist_name_manifest}
   - ${__cdist_name_explorer}
   - ${__cdist_name_gencode}

eof
__prompt "$continue"


cat << eof

Every type must have a directory named ${__cdist_name_parameter}, which
contains required or optional parameters (in newline seperated files).

If an object of a specific type was created in the initial manifest,
the manifest of the type is run and may create other objects.

A type may have ${__cdist_name_explorer}, which are very similar to the
${__cdist_name_explorer} seen above, but with a different purpose:
They are specific to the type and are not relevant for other types.

You may use them for instance to find out details on the target host,
so you can decide what to do on the target host eventually.

After the ${__cdist_name_manifest} and the ${__cdist_name_explorer} of
a type have been run, ${__cdist_name_gencode} is executed, which creates
code to be executed on the target on stdout.

eof
__prompt "$continue"

################################################################################
# Deployment
#

cat << eof

Now you've got some basic knowledge about cdist, let's configure your localhost!

Ensure that you have a ssh server running locally and that you can login as root.

The cdist distribution contains some sensible default initial manifest, which
will create 2 files, /etc/cdist-configured (for every host) and
/tmp/cdist-testfile (only for localhost).

eof

cmd="cdist-deploy-to localhost"

__prompt "Press enter to run \"$cmd\""

# No quotes, we need field splitting
$cmd

################################################################################
# End
#

cat << eof

That's it, this is the end of the cdist-introduction.

I hope you've got some impression on how cdist works, here are again some
pointers on where to continue to read:

cdist(7), cdist-deploy-to(1), cdist-type(7), cdist-stages(7)

eof