Puppet

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Introduction

Puppet is a well-known open source configuration & system management tool.


Puppet Issues

Random issues noted by puppet users.

  • Naginator in recent versions is broken on nagios < 3.0
  • the Interface type has gone away (use templates - see http://reductivelabs.com/trac/puppet/wiki/NetworkInterfacesTemplate)
  • Caching issues - these seem to crop up all the time. Possible fixes depending on the case:
    • Restart puppetmasterd
    • Clear out state files e.g. /var/lib/puppet/state/* on the client
    • Clear out cached node(s) and/or facts e.g. /var/lib/puppet/yaml/*/* on the puppetmaster server(s)
  • contact_groups not a valid attribute of Nagios_host?! WTF? Bug in 0.24.4

Puppet Links

Installation

Operations

Trigger a client run

You can send puppetd (client) a USR1 signal to trigger it to run. I usually tack on the syslog tailer to see what it's doing. 

# ps ax | grep pupp
9605 ?        Ssl    3:43 ruby /usr/sbin/puppetd -w 0
...
# kill -USR1 9605; tail -f /var/log/syslog

This way also works (e.g. on Debian) if you know the pid path... 

kill -USR1 `cat /var/run/puppet/puppetd.pid`; tail -f /var/log/syslog

Parsing a (class) file

This is how to do a a syntax check on a file. 

puppet --parseonly --ignoreimport <filename> #e.g. ruby-server.pp 
err: Could not parse for environment development: Syntax error at ';'; expected ']' 
at /etc/puppet/manifests/classes/ruby-server.pp:2


Providers

Users

Make sure to install libshadow-ruby1.8 on Debian/Ubuntu or libshadow on Fedora/Red Hat/CentOS

In a @user declaration, when specifying a password, do not use double-quote... instead use single-quotes, e.g. 

password => '$1$LU.r1qgx$XbcRiNjgXc3ZDtuJaOu4n0'

Otherwise the $ will trigger interpolation.

Packages

Gems

This example shows how to install a specific version of a gem. 

      package { "cached_model":
              ensure => "1.2.1",
              provider => gem
      }

Resource Relationships

Metaparameters such as before, subscribe, notify and ensure can be used to designate relationships between resources.

before

Use before to indicate that this resource has to be applied first, before something else.

require

This should be used to indicate that some other resource is a prerequisite. 

file  { sshd_config:
 ... 
 require => Package[ssh]
}

This says "make sure the ssh package (defined elsewhere as a package resource) is installed before applying this file resource".

ensure

Ways to use ensure.

Ensure the latest version of a package is installed. 

package { ssh: ensure => latest, ... }

Ensure a specific version of a packages is installed

(See the gem example above)

Ensure a service is running. 

service {  snmpd: ensure => running, ... }

Ensure a file exists. 

file { "/some/file": ensure => exists,  ... }

Ensure a directory exists. (Confusing as it appears in a file resource. 

file { "/some/folder": ensure => directory, ... }

Ensure a soft-link exists. 

file { "/some/file": ensure => link, target => "/some/existing/file" }

Ensure a package is absent i.e. not installed 

package { "smartd": ensure => absent }

subscribe

The 'subscribe' attribute in a service causes the service to restart if the configuration file changes. 

service { "foo": subscribe => File["foo.conf"], ... }

Puppet Types

file

Create a soft-link (Example) 

 file { "/var/log/apache":
   ensure => link,
   target => "/var/log/apache2",
 }

Overloading

You can do things like this with existing types... 

Package { require => Exec["apt-get update]" }

For inherited resource types, you can modify attributes. Don't try this with (simply) included resources. 

File["/etc/nsswitch.conf] { group => foo }


Puppet development

In order to work on new features and bugfixes for puppet here is how I set that up. (See this link also.

First, install the pre-reqs. 

aptitude install libxmlrpc-ruby, libopenssl-ruby libshadow-ruby

Check out the puppet code 

 mkdir -p ~/git && cd ~/git
 git clone git://github.com/puppetlabs/puppet

This puts everything in ~/git/puppet. 

 cd puppet
 sudo ./install.rb

I proceed to make my changes. 

mdf@sushi:~/git/puppet$ vi lib/puppet/type/package.rb 
mdf@sushi:~/git/puppet$ ruby -c lib/puppet/type/package.rb
Syntax OK
  • Test changes (TBD)
sudo /usr/sbin/puppetd --no-daemonize --verbose
  • Create diffs for my changes
cd ~/git/puppet
git diff


Package install problems

Various packages will fail to install via puppet.


Java

Most common difficulty is install java automatically under Ubuntu, because apt wants some interaction to accept the license agreement. The exec below will lay down the file indicating acceptance (via require). Same methodology can be used for other packages which enforce user interaction. 

  case $operatingsystem {
    debian,ubuntu: {
      exec {"pre-accept-sun-dlj":
        path => "/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin",
        cwd => "/tmp",
        command => 'echo "sun-java6-bin shared/accepted-sun-dlj-v1-1 boolean true" | debconf-set-selections && touch /var/lib/puppet/state/accepted-sun-dlj-v1-1',
        unless => "test -e /var/lib/puppet/state/accepted-sun-dlj-v1-1",
      }
    }
  }

Dell OMSA

Another case is OMSA and any packages that are either un-signed or signed by an untrusted source. If it an a PPA repo (see launchpad) you can require the key be installed. 

 file {"bp-ppa":
   name => "/etc/apt/sources.list.d/bp-ppa.list",
   content => template("bitpusher/etc/apt/sources.list.d/bp-ppa.list"),
   owner => root, group => root,
   notify => Exec["install-ppa-key"],
 }
 
 exec { "install-ppa-key":
   command => "/usr/bin/wget -O - http://www.bitpusher.com/ppa.key | /usr/bin/apt-key add -",
   refreshonly => true,
   unless => "/usr/bin/apt-key list | grep 63FF8D62",
   notify => Exec["apt-update"],
   require => Package[gnupg],
 }
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