path: root/documentation/faq.page

---
inMenu: true
title: FAQ
---
What is Puppet?
----------------
Puppet is an open-source next-generation server automation tool.  It is
composed of a *declarative* language for expressing system configuration, a
*client* and *server* for distributing it, and a *library* for realizing the
configuration.

The primary design goal of Puppet is that it have an expressive enough
language backed by a powerful enough library that you can write your own
server automation applications in just a few lines of code.  With Puppet, you
can express the configuration of your entire network in one program capable of
realizing the configuration.  The fact that Puppet has open source combined
with how easily it can be extended means that you can add whatever
functionality you think is missing and then contribute it back to the main
project if you desire.

You can learn more about Puppet by reading its [Documentation][].

What license is Puppet released under?
--------------------------------------
Puppet is open source and is released under the [GNU Public License][].

Why does Puppet exist?
----------------------
Luke Kanies, who founded Reductive Labs, has been doing server automation for
years, and Puppet is the result of his frustration with existing tools.  After
significant effort spent trying to enhance cfengine, plus a stint at a
commercial server automation vendor, Luke concluded that the only way to get a
great automation tool was to develop one.

Puppet is actually the result of years of design and prototyping (called Blink
during its prototype phases), but only in 2005 was a commercial company
(Reductive Labs) built to be fully dedicated to its creation.  If Puppet is
not the most powerful and most flexible server automation platform available,
then its goals are not being met.

Why does Puppet have its own language?
--------------------------------------
This actually is a frequently asked question, and people most often ask why I
did not choose to use something like XML or YAML as the configuration
format; otherwise people ask why I didn't just choose to just use Ruby as the
input language.

The input format for Puppet is not XML or YAML because these are data formats
developed to be easy for computers to handle.  They do not do conditionals
(although, yes, they support data structures that could be considered
conditionals), but mostly, they're just horrible human interfaces.  While some
people are comfortable reading and writing them, there's a reason why we use
web browsers instead of just reading the HTML directly.  Also, using XML or
YAML would limit the ability to make sure the interface is declarative -- one
process might treat an XML configuration differently from another.

As to just using Ruby as the input format, that unnecessarily ties Puppet to
Ruby, which is undesirable, and Ruby provides a bit too much functionality.
For more detail, see the [thread][] on the puppet-dev list.


How does Puppet compare to cfengine?
------------------------------------
Puppet could be said to be the next-generation cfengine.  The overall design
is heavily influenced by cfengine, but the language is more powerful than
cfengine's and the library is more flexible.  In addition, Puppet's client and
server use standard protocols like XMLRPC and are easy to enhance with new
functionality, so they are well-positioned to become the platform for the
network applications of the future, while cfengine's client and server rely
entirely on cfengine-specific protocols and are quite difficult to enhance.

See [How Puppet Compares to Cfengine][] for more information.

How does Puppet compare to available commercial products?
---------------------------------------------------------
The primary commercial vendors are BladeLogic and OpsWare.  While they both
have useful product lines, Puppet surpasses them by reframing the entire
server automation problem -- while the commercial vendors are writing GUI
applications for you, Reductive Labs is providing a development platform with
all the features of a great language, like library development, code sharing,
and the ability to version control your configurations.

Trying to express a complex network configuration entirely through a GUI is an
exercise in frustration that no one should suffer, but expressing the
abstraction necessary to share those GUI configurations goes beyond
frustrating.

Of course, another great difference between Puppet and the commercial products
is that Puppet is open sourced under the [GNU Public License][].  You can
[download][] the product, try it out, peruse the source, and make whatever
modifications you want.  You have to have more than 100 servers just to get a
demo from the commercial vendors, but Puppet is available for testing by any
company that needs to reduce its server administration costs.

Who would find Puppet useful?
-----------------------------
Any organization that would like to reduce the cost of maintaining its
computers could benefit from using Puppet.  However, because the return on
investment is linked to multiple factors, like current administrative
overhead, diversity among existing computers, and cost of downtime, it can be
difficult for organizations to determine whether they should invest in any
configuration management tools, much less Puppet.  Reductive Labs can always
be contacted directly at info at reductivelabs.com to help answer this question.

Generally, however, an organization should be using server automation if any
of the following are true:

* It has high server administration costs
* It pays a high price for downtime, either because of contracts or
  opportunity cost
* It has many servers that are essentially either identical or nearly
  identical
* Flexibility and agility in server configuration are essential

Can Puppet manage workstations?
-------------------------------
Yes, Puppet can manage any type of machine.  We have found that most
organizations are more concerned with server management than workstation
management, and frankly, the term 'server' is slightly more aesthetically
appealing than 'computer', but Puppet would be ideal for organizations with a
large number of workstations.

Does Puppet run on Windows?
---------------------------
The short answer is 'not yet'.  It will eventually, but Reductive Labs does
not yet have the development bandwidth to make this work.

What size organizations should use Puppet?
------------------------------------------
There is no minimum or maximum organization size that can benefit from Puppet,
but there are sizes that are more likely to benefit.  Organizations with fewer
than 10-20 servers are unlikely to consider maintaining those servers to be a
real problem, and thus they can avoid investment in tools even though those
tools could likely provide savings.

There is no real upper limit to who could benefit from using Puppet.
Obviously as the server count increases the investment must increase somewhat,
but with Puppet that increase is not linear.

My servers are all unique; can Puppet still help?
-------------------------------------------------
All servers are at least somewhat unique -- with different host names and
different IP addresses -- but very few servers are entirely unique, since
nearly every one runs a relatively standard operating system.  Servers are
also often very similar to other servers within a single organization -- all
Solaris servers might have similar security settings, or all web servers might
have roughly equivalent configurations -- even if they're very different from
servers in other organizations.  Finally, servers are often needlessly unique,
in that they have been built and managed manually with no attempt at retaining
appropriate consistency.

Puppet can help both on the side of consistency and uniqueness.  Puppet
can be used to express the consistency that should exist, even if
that consistency spans arbritrary sets of servers based on any type of data
like operating system, data center, or physical location.  Puppet can also be
used to handle uniqueness, either by allowing special provision of what makes
a given host unique or through specifying exceptions to otherwise standard
classes.

Who is Reductive Labs?
----------------------
Reductive Labs is a small, private company focused on reframing the server
automation problem.  Our primary focus is Puppet, but Reductive Labs also
provides automation consulting, training, and custom development.  For more
information email info at reductivelabs.com.

The [Projects][] page lists our active projects.

How Do I Install Puppet?
------------------------

The [Installation Guide][] documents the fastest way to start using Puppet.

What is a Manifest?
-------------------
Because the word *script* implies a procedural one-step-after-another program,
the word does not apply well to Puppet programs.  Thus, we use the word
*manifest* to describe declarative Puppet programs.  Speaking of applying,
Puppet *applies* a manifest to a server or a network, rather than *executing*
it.

How Do I Write Manifests?
-------------------------
The best way is to download Puppet and just start writing.  There are multiple
sets of examples, including the [examples][] used in [unit testing][],
and the [reference][]will obviously be useful.

How Do I Run Manifests?
-----------------------
Once you have Puppet installed according the the [Installation Guide][],
just run the ``puppet`` executable against your example:

    puppet -v example.pp

How do I contribute?
--------------------
First join the [Mailing List][] -- there is currently only a development list,
but as the community grows a user list will be created.  You can also join the
IRC channel ``#puppet`` on irc.freenode.net, where Puppet's developers will be
hanging out most days (and nights).

The most valuable contribution you can make, though, is to use Puppet and
submit your feedback, either directly on IRC or through the mailing list, or
via the [bug database][].  We're always looking for great ideas to incorporate
into Puppet.

When is the Next Release?
-------------------------
There are regular feature and release updates on the [Mailing List][],
and you can always find the latest release in the [download][] directory.

I keep getting "certificates were not trusted".  What's wrong?
--------------------------------------------------------------
Historically this has usually been a problem with the client machine having
such a different date setting that the certificate is not yet valid.

You can figure the problem out by manually verifying the certificate with
openssl:

    sudo openssl verify -CAfile /etc/puppet/ssl/certs/ca.pem /etc/puppet/ssl/certs/myhostname.domain.com.pem

[Mailing List]: http://mail.madstop.com/mailman/listinfo/puppet-dev
[Projects]: /projects/
[Documentation]: index.html
[Installation Guide]: installation.html
[How Puppet Compares to Cfengine]: notcfengine.html
[GNU Public License]: http://www.gnu.org/copyleft/gpl.html
[examples]: /cgi-bin/puppet.cgi/browser/trunk/examples/code/
[unit testing]: http://www.pragmaticprogrammer.com/starter_kit/ut/
[bug database]: /cgi-bin/puppet.cgi/report
[reference]: typedocs.html
[download]: /downloads
[thread]: http://mail.madstop.com/pipermail/puppet-dev/2006-April/000393.html

*$Id$*