Slides from a talk I have given at Config Management Camp 2017 about the Puppet DSL and some features that are really useful but that few people use.

1. Puppet DSL: Back to the basics
Julien Pivotto (@roidelapluie)
Config Management Camp Ghent
February 2017

2. $::user
Julien Pivotto
@roidelapluie on irc/github/twitter
Puppet user since 2011 (Puppet 0.24)
VoxPupuli member (& security officer)

3. inuits

4. Scope
What didn't we notice in Puppet DSL over the
last years?
How much backwards compatibility?

5. Why?
There are lots of new exciting features
But the puppet DSL has a strong trunk
Puppet 3 is EOL, so we can use most of these
things

6. Tooling
Puppet parser validate
Puppet-lint 2 (with plugins)
$EDITOR puppet syntax

7. Custom facts
FACTER_bootstrap=true puppet agent ­­test
Useful for 1-time facts, or overwriting existing
facts (e.g ipaddress) without code.

8. Puppet DSL

9. The File resource
file { '/etc/motd'
ensure => file,
content => 'foobarbarfoofoobar',
}

10. content => file()
file { '/etc/motd':
ensure => file,
content => file("${module_name}/motd")
}
For small, text files (file content is in the catalog)
Since Puppet 3.7.0

11. validate_cmd
file { '/etc/corosync/corosync.conf':
ensure => file,
validate_cmd => '/usr/sbin/corosync ­t %',
}
Verify the file before replacing it
Since Puppet 3.5.0
Alternative in stdlib for older versions

12. show_diff
file { '/etc/app/secrets':
content => 'my secret content',
show_diff => false,
}
Since Puppet 3.2.1

13. replace
file { '/etc/installtime':
content => template('date.erb'),
replace => no,
}
Since Puppet 0.19.0

14. backup
file { '/etc/hosts':
content => template('hosts.erb'),
backup => '.bak',
}
Since a very long time...

15. source
file {
'/etc/issue.net':
source => '/etc/motd'
}
Since a very long time...

16. autorequires
Don't do:
file {
'/tmp':
}
file {
'/tmp/foo':
require => File['/tmp'],
}
because files auto-require their parents (and
owners, groups...)
Since Puppet 0.10.2

17. other autorequires
Exec, Cron require their users
Mount require its parents
Exec requires its File[cwd]

18. other autodependencies
resources types can implement autonotify and
autosubscribe
(this is used in puppet-corosync)
Since Puppet 4.0.0

19. noop
package {
'ntpd':
ensure => latest,
noop => true,
}
noop is not only a global setting - it is also a
metaparameter that can be applied to any
resource
Present since a very long time...

20. purging resources
resources {
'cron':
purge => true,
noop => true,
}
Present since Puppet 0.22.0
Present since 3.5.0 (for cron resources)

21. exec tries
exec {
'/bin/wget 127.0.0.1':
tries => 10,
try_sleep => 1,
}
Present since Puppet 2.6.0

22. arrays
file {
'/usr/bin/sometimesexecutable':
mode => ['0755', '0644']
}
Will accept both modes, and set 0755 if not
matching.
Can be used with most of the properties.
Since Puppet 0.23.1

23. Requirements
define foo::bar {
Package['foo'] ­> Foo::Bar[$name]
}
Is the same as:
foo::bar {'barfoo':
require => Package['foo']
}

24. Aliases
Instead of:
file { "/tmp/foo/bar/bar.foo/foobar":
ensure => file,
}
service { 'barfoo':
require => File["/tmp/foo/bar/bar.foo/foobar"
}

25. Aliases
Use:
file {"/tmp/foo/bar/bar.foo/foobar":
ensure => file,
alias => 'foobar'
}
service {'barfoo':
require => File["foobar"]
}
Since a very long time...

26. Loglevel
exec {
'/bin/mybrokenexec':
loglevel => debug,
}
Since Puppet 0.23.1

27. Next to the DSL...

28. The Puppet resource face
$ puppet resource file /home/u/.vimrc
file { '/home/u/.vimrc':
ensure => 'file',
content => '{md5}d414e9800998ecf8427e',
ctime => '2017­02­06 10:09:05 +0100',
group => '1000',
mode => '0644',
mtime => '2017­02­06 10:09:05 +0100',
owner => '1000',
type => 'file',
}
$ puppet resource file .hushlogin mode=0755
Since Puppet 2.7

29. Pluginsync
Im modules:
lib/puppet/reports/prometheus.rb
lib/augeas/lenses/tmpfiles.aug

30. Julien Pivotto
roidelapluie
roidelapluie@inuits.eu
Inuits
https://inuits.eu
info@inuits.eu
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