Project: Puppet (Provisioning / Automation & Configuration)
File: catalogs.md

When working on subsystems of Puppet that deal with the catalog it is important to be aware of the two different types of Catalogs. The two different types of catalogs becomes relevant when writing spec tests because we frequently need to wire up a fake catalog so that we can exercise types, providers, or termini that filter the catalog. The two different types of catalogs are so-called "resource" catalogs and "RAL" (resource abstraction layer) catalogs. At a high level, the resource catalog is the in-memory object we serialize and transfer around the network. The compiler terminus is expected to produce a resource catalog. The agent takes a resource catalog and converts it into a RAL catalog. The RAL catalog is what is used to apply the configuration model to the system. Resource dependency information is most easily obtained from a RAL catalog by walking the graph instance produced by the `relationship_graph` method. If you're writing spec tests for something that deals with a catalog "server side," a new catalog terminus for example, then you'll be dealing with a resource catalog. You can produce a resource catalog suitable for spec tests using something like this: ```ruby let(:catalog) do catalog = Puppet::Resource::Catalog.new("node-name-val") # NOT certname! rsrc = Puppet::Resource.new("file", "sshd_config", :parameters => { :ensure => 'file', :source => 'puppet:///modules/filetest/sshd_config', } ) rsrc.file = 'site.pp' rsrc.line = 21 catalog.add_resource(rsrc) end ``` The resources in this catalog may be accessed using `catalog.resources`. Resource dependencies are not easily walked using a resource catalog however. To walk the dependency tree convert the catalog to a RAL catalog as described in The resource catalog may be converted to a RAL catalog using `catalog.to_ral`. The RAL catalog contains `Puppet::Type` instances instead of `Puppet::Resource` instances as is the case with the resource

One very useful feature of the RAL catalog are the methods to work with resource relationships. For example: irb> catalog = catalog.to_ral irb> graph = catalog.relationship_graph irb> pp graph.edges [{ Notify[alpha] => File[/tmp/file_20.txt] }, { Notify[alpha] => File[/tmp/file_21.txt] }, { Notify[alpha] => File[/tmp/file_22.txt] }, { Notify[alpha] => File[/tmp/file_23.txt] }, { Notify[alpha] => File[/tmp/file_24.txt] }, { Notify[alpha] => File[/tmp/file_25.txt] }, { Notify[alpha] => File[/tmp/file_26.txt] }, { Notify[alpha] => File[/tmp/file_27.txt] }, { Notify[alpha] => File[/tmp/file_28.txt] }, { Notify[alpha] => File[/tmp/file_29.txt] }, { File[/tmp/file_20.txt] => Notify[omega] }, { File[/tmp/file_21.txt] => Notify[omega] }, { File[/tmp/file_22.txt] => Notify[omega] }, { File[/tmp/file_23.txt] => Notify[omega] }, { File[/tmp/file_24.txt] => Notify[omega] }, { File[/tmp/file_25.txt] => Notify[omega] }, { File[/tmp/file_26.txt] => Notify[omega] }, { File[/tmp/file_27.txt] => Notify[omega] }, { File[/tmp/file_28.txt] => Notify[omega] }, { File[/tmp/file_29.txt] => Notify[omega] }] If the `relationship_graph` method is throwing exceptions at you, there's a good chance the catalog is not a RAL catalog. Be aware that Puppet creates a mini catalog and applies this catalog locally to manage file resource from the settings. This behavior made it difficult and time consuming to track down a race condition in . Even more surprising, the `File[puppetdlockfile]` resource is only added to the settings catalog if the file exists on disk. This caused the race condition as it will exist when a separate process holds the lock while applying the catalog. It may be sufficient to simply be aware of the settings catalog and the potential for race conditions it presents. An effective way to be reasonably sure and track down the problem is to wrap the File.open method like so: ```ruby class File WHITELIST = [ /pidlock.rb:39/ ] class << self alias xxxorigopen open end def self.open(name, *rest, &block) puppetdlock file white_listed = caller(0).find do |line| JJM_WHITELIST.find { |re| re.match(line) } end binding.pry if name =~ /puppetdlock/ and not white_listed xxxorigopen(name, *rest, &block) end end ``` The settings catalog is populated by the `Puppet::Util::Settings#to\_catalog` method.