Fixing #2914 - pre/post hooks now work for transactions

This was built to be used with etckeeper to version control
files in /etc, but can be used for essentially anything.

This patch was built to be added to 0.25.4, so it's a least-modify
approach.  A better approach would be to refactor application/puppet.rb
just a bit so it uses Configurer more.

This is a simple patch - it just defines 'prerun_command' and 'postrun_command'
settings, and runs the appropriate command around each transaction
if they're set.

Signed-off-by: Luke Kanies <luke@reductivelabs.com>

3 files changed, 37 insertions, 4 deletions

diff --git a/lib/puppet/application/puppet.rb b/lib/puppet/application/puppet.rb
index 2929d54e8..273c7d0e7 100644
--- a/lib/puppet/application/puppet.rb
+++ b/lib/puppet/application/puppet.rb
@@ -1,5 +1,6 @@
 require 'puppet'
 require 'puppet/application'
+require 'puppet/configurer'
 require 'puppet/network/handler'
 require 'puppet/network/client'
 
@@ -124,9 +125,14 @@ Puppet::Application.new(:puppet) do
 
             catalog.retrieval_duration = Time.now - starttime
 
+            configurer = Puppet::Configurer.new
+            configurer.execute_prerun_command
+
             # And apply it
             transaction = catalog.apply
 
+            configurer.execute_postrun_command
+
             status = 0
             if not Puppet[:noop] and options[:detailed_exitcodes] then
                 transaction.generate_report
@@ -135,9 +141,7 @@ Puppet::Application.new(:puppet) do
             end
             exit(status)
         rescue => detail
-            if Puppet[:trace]
-                puts detail.backtrace
-            end
+            puts detail.backtrace if Puppet[:trace]
             if detail.is_a?(XMLRPC::FaultException)
                 $stderr.puts detail.message
             else
diff --git a/lib/puppet/configurer.rb b/lib/puppet/configurer.rb
index 3e72fa574..ec61272ef 100644
--- a/lib/puppet/configurer.rb
+++ b/lib/puppet/configurer.rb
@@ -5,6 +5,8 @@ require 'puppet/network/http_pool'
 require 'puppet/util'
 
 class Puppet::Configurer
+    class CommandHookError < RuntimeError; end
+
     require 'puppet/configurer/fact_handler'
     require 'puppet/configurer/plugin_handler'
 
@@ -39,6 +41,14 @@ class Puppet::Configurer
         @catalog = nil
     end
 
+    def execute_postrun_command
+        execute_from_setting(:postrun_command)
+    end
+
+    def execute_prerun_command
+        execute_from_setting(:prerun_command)
+    end
+
     # Initialize and load storage
     def dostorage
         begin
@@ -75,6 +85,8 @@ class Puppet::Configurer
         download_plugins()
 
         download_fact_plugins()
+
+        execute_prerun_command
     end
 
     # Get the remote catalog, yo.  Returns nil if no catalog can be found.
@@ -160,6 +172,8 @@ class Puppet::Configurer
         # Now close all of our existing http connections, since there's no
         # reason to leave them lying open.
         Puppet::Network::HttpPool.clear_http_instances
+    ensure
+        execute_postrun_command
     end
 
     private
@@ -180,4 +194,14 @@ class Puppet::Configurer
 
         return timeout
     end
+
+    def execute_from_setting(setting)
+        return if (command = Puppet[setting]) == ""
+
+        begin
+            Puppet::Util.execute([command])
+        rescue => detail
+            raise CommandHookError, "Could not run command from #{setting}: #{detail}"
+        end
+    end
 end
diff --git a/lib/puppet/defaults.rb b/lib/puppet/defaults.rb
index 6b9c43b81..21cee7a05 100644
--- a/lib/puppet/defaults.rb
+++ b/lib/puppet/defaults.rb
@@ -199,7 +199,12 @@ module Puppet
             reports, allowing you to correlate changes on your hosts to the source version on the server."],
         :zlib => [true, 
             "Boolean; whether to use the zlib library",
-        ]
+        ],
+        :prerun_command => ["", "A command to run before every agent run.  If this command returns a non-zero
+            return code, the entire Puppet run will fail."],
+        :postrun_command => ["", "A command to run after every agent run.  If this command returns a non-zero
+            return code, the entire Puppet run will be considered to have failed, even though it might have
+            performed work during the normal run."]
     )
 
     hostname = Facter["hostname"].value