Added an example of a Libral provider using Puppet directly

contrib/puppet/Dockerfile

@@ -12,5 +12,6 @@ RUN apt-get update && \
 ENV PATH=/usr/src/ral/bin:$PATH
 
 COPY apt_libral /etc/puppetlabs/code/modules/apt_libral
+COPY puppet.prov /usr/src/ral/data/providers
 
 CMD ["resource", "apt_libral"] 

contrib/puppet/README.md

@@ -1,6 +1,6 @@
 # Integrating Libral with Puppet
 
-This folder contains a simple example of integrating Puppet with Libral, specifically exposing Libral providers to Puppet. This is not intended to be a complete solution, more at early working prototype.
+This folder contains a simple example of integrating Puppet with Libral, specifically exposing Libral providers to Puppet and using Puppet as a Libral provider. This is not intended to be a complete solution, more an early working prototype.
 
 You can see this working with the accompanying Dockerfile.The image contains both Puppet and Libral, along with Ralsh.
 
@@ -40,10 +40,43 @@ apt_libral { 'base-files':
   ensure   => '9.4ubuntu4.5',
 ```
 
+This example also contains an example Libral provider which uses Puppet under the hood. This is incredibly blunt, in that it shells out and then naively parses the returned YAML (MRuby isn't built with the YAML gem yet), but it demonstrates this works. For instance lets run our new provider via Ralsh.
+
+```
+$ docker run --entrypoint ralsh puppet/puppet-libral -l none group::puppet | head
+group::puppet { 'adm':
+  ensure => 'present',
+  gid    => '4',
+}
+group::puppet { 'audio':
+  ensure => 'present',
+  gid    => '29',
+}
+group::puppet { 'backup':
+  ensure => 'present',
+```
+
+Compare that with the groupadd provider which already ships with libral:
+
+```
+$ docker run --entrypoint ralsh puppet/puppet-libral -l none group::puppet root
+group::puppet { 'root':
+  ensure => 'present',
+  gid    => '0',
+}
+
+$ docker run --entrypoint ralsh puppet/puppet-libral -l none group::groupadd root
+group::groupadd { 'root':
+  ensure => 'present',
+  gid    => '0',
+}
+```
+
 ## Notes
 
 * This only looks at `list` operations so far
-* The types could be autogenerated from the libral providers, or loaded dynamically at runtime
+* The Puppet types could be autogenerated from the libral providers, or loaded dynamically at runtime
+* The libral types, and provider code, could be autogenerated from the Puppet types. Some prior-art around extraction in https://github.com/puppetlabs/pcore-to-jsonschema
 * The providers are nearly 100% boilerplate, which should mean we can have a simple base class which does all the work for any libral provider
 * The exception is type-specific fields, which again can be autogenerated or parsed from the provider/ralsh at runtime
-* I've implemented both a simple provider and a ralsh provider. A JSON provider would be simple enough, and once https://github.com/puppetlabs/libral/pull/25 is working it should be possible to use the native Ruby interface. I'm doing this for completeness, in reality we'd probably pick one
+* I've implemented both a simple provider and a ralsh provider. A JSON provider would be simple enough to add, and once https://github.com/puppetlabs/libral/pull/25 is working it should be possible to use the native Ruby interface. I'm doing this for completeness, in reality we'd probably pick one

contrib/puppet/puppet.prov

@@ -0,0 +1,53 @@
+#! /usr/bin/env mruby
+# -*- ruby -*-
+
+
+class Group
+  def describe(ctx)
+    puts <<EOS
+---
+provider:
+  type: group
+  desc: |
+    Puppet group
+  invoke: json
+  actions: [get]
+  suitable: true
+  attributes:
+    name:
+      desc: "The name of the group"
+    ensure:
+      type: enum[absent, present]
+    gid:
+      desc: "The group ID"
+EOS
+  end
+
+  def get(ctx, names)
+      output = `puppet resource group --to_yaml`
+      lines = output.split("\n")
+      resources = {}
+      lines.each do |line|
+        unless line == "group:"
+	  key, value = line.split(":", 2)
+	  if (value.nil? || value.empty?) and !key.nil?
+	    $name = key.strip
+	    resources[$name] = {}
+	  else
+            unless $name.nil? or key.nil?
+	      resources[$name][key.strip] = value.strip.gsub("'", '')
+            end
+	  end
+	end
+      end
+      resources.collect do |name, resource|
+        {
+          "name" => name,
+          "ensure" => resource["ensure"],
+          "gid" => resource["gid"],
+        }
+      end
+  end
+end
+
+Ral::CLI::run(Group)