The document discusses converting Puppet exec commands into types and providers, highlighting the structure and functionalities of user management and apt key management types. It details how properties and parameters work, along with examples of creating custom types and providers, conducting validations, and managing resource existence. Additionally, it points to resources for further information on Puppet types and provider development.

1. Replacing "exec" with a
type and provider
Return manifests to a declarative
configuration
Dominic Cleal <dcleal@redhat.com>

2. Puppet's declarative DSL
user { 'dcleal':
ensure => present,
comment => 'Dominic Cleal',
shell => '/bin/bash',
}
package { 'vim':
ensure => 'present',
}

3. How execs can fail
$ puppet module install puppetlabs-apt
$ vim apt/manifests/key.pp
...
exec { "apt::key ${upkey} absent":
command => "apt-key del '${upkey}'",
path => '/bin:/usr/bin',
onlyif => "apt-key list | grep '${upkey}'",
user => 'root',
group => 'root',
logoutput => 'on_failure',
}

4. Convert the exec to a type/provider
'user' type
ensure
name
comment
'useradd'
shell
home provider
exists?, create, destroy
comment, comment=
useradd <user>
shell, shell=
home, home=
usermod <user>
userdel <user>

5. Types: properties and parameters
● Properties are changeable, e.g. a user's
shell or a service's start-at-boot flag
● Parameters represent other required data, e.
g. hasrestart on service
● All data can be validated and munged
● Types can be "ensurable", if the object can:
○ exist and not exist
○ be created
○ be destroyed

6. Convert the exec to a type/provider
'apt_key' type
ensure
key 'keyring' provider
key_server exists?
create apt-key list
destroy
apt-key --recv-keys..
apt-key del

7. Types: simple example
$ cat apt_key/lib/puppet/type/apt_key.rb
Puppet::Type.newtype(:apt_key) do
@doc = "Manages apt keys"
ensurable
newparam(:key) do
desc "The key ID"
isnamevar
end
newparam(:key_server) do
desc "Key server to download key form"
defaultto "pgp.mit.edu"
end
end

8. Types: known values
Puppet::Type.type(:file).newparam(:checksum) do
desc "The checksum type to use when
determining whether to replace a file's conten
ts.
The default checksum type is md5."
newvalues "md5", "md5lite", "mtime", "ctime",
"none"
defaultto :md5
end

9. Types: validation
module Puppet
newtype(:schedule) do
newparam(:repeat) do
desc "How often a given resource may be applied
in this schedule's `period`. Defaults to 1; must be an
integer."
validate do |value|
unless value.is_a?(Integer) or value =~
/^d+$/
raise Puppet::Error,
"Repeat must be a number"
end
end

10. Providers: getters/setters, ensurable
● getters and setters are implemented for each
property
● ensurable types also have exists?, create
and destroy to manage its existence
● list of commands that are required to run
● confined to certain operating systems via
facts

11. Providers: simple example
$ cat apt_key/lib/puppet/provider/apt_key/keyring.rb
Puppet::Type.type(:apt_key).provide(:keyring) do
commands :aptkey => "/usr/bin/apt-key"
def exists?
aptkey("list").include? resource[:key].upcase
end
def create
aptkey "adv", "--keyserver", resource[:key_server], "--recv-
keys", resource[:key].upcase
end
def destroy
aptkey "del", resource[:key].upcase
end
end

12. Providers: confinement
Puppet::Type.type(:group).provide :aix do
desc "Group management for AIX."
confine :operatingsystem => :aix
defaultfor :operatingsystem => :aix
Puppet::Type.type(:exec).provide :posix do
confine :feature => :posix
defaultfor :feature => :posix

13. Providers: instances and ralsh
$ puppet resource host
host { 'argon':
ensure => 'present',
host_aliases => ['foo'],
ip => '192.168.0.10',
target => '/etc/hosts',
}
host { 'iridium':
ensure => 'present',
host_aliases => ['localhost.localdomain', 'localhost'],
ip => '127.0.0.1',
target => '/etc/hosts',
}

14. Providers: instances and ralsh
def self.instances
resources = []
aptkey("list").each_line { |k| resources << new({:
name => $1}) if k =~ /^pubs+w+/(w+)/ }
resources
end
# puppet resource apt_key
apt_key { '1F41B907':
ensure => 'present'
}
apt_key { '46925553':
ensure => 'present'

15. Testing providers with rspec
prov_c = Puppet::Type.type(:apt_key).provider(:keyring)
describe prov_c do
it "should remove key" do
resource = Puppet::Type.type(:apt_key).new(
:name => '16BA136C',
:ensure => :absent
)
provider = prov_c.new(resource)
provider.expects(:aptkey).with('del', '16BA136C')
provider.destroy
end
end

16. Creating a module
$ puppet module generate domcleal-apt_key
$ cd domcleal-apt_key
$ mkdir -p lib/puppet/type
lib/puppet/provider/apt_key
$ touch lib/puppet/type/apt_key.rb
lib/puppet/provider/apy_key/keyring.rb
$ puppet module build .
upload pkg/domcleal-apt_key-0.0.1.tar.gz

17. Resources
● docs.puppetlabs.com guides
○ Writing custom types & providers
○ Provider development
● Puppet Types and Providers
○ Dan Bode & Nan Liu, O'Reilly, 2012
● puppet source itself, spec/unit/provider/
● puppetlabs_spec_helper