Merge pull request #2700 from nickanderson/ENT-10481/master

ENT-10481: Added ability to enable backup archives during policy update

MPF.md

@@ -1720,7 +1720,49 @@ For example:
 }
 ```
 
-**History**: Added in 3.10.1
+**Notes:**
+
+- This applies to `promises.cf`.
+
+
+**History:**
+
+- Introduced in CFEngine 3.10.1
+
+### Configure default repository for file backups during policy update
+
+By default the agent creates a backup of a file before it is edited in the same
+directory as the edited file. This happens during policy update but the backup
+files are culled by default as part of the default sync behavior.
+
+Defining the `default:mpf_update_control_agent_default_repository` class will
+cause these backups to be placed in `$(sys.workdir)/backups`. Customize the
+backup directory by setting `default:update_def.control_agent_default_backup`.
+
+For example:
+
+```
+{
+  "classes": {
+    "default:mpf_update_control_agent_default_repository": {
+      "class_expressions": [ "any::" ]
+    }
+  },
+  "variables": {
+    "default:update_def.control_agent_default_repository": {
+      "value": "/var/cfengine/policy-update-backups"
+    }
+  }
+}
+```
+
+**Notes:**
+
+- This applies to `update.cf`.
+
+**History:**
+
+- Introduced in CFEngine 3.23.0
 
 ### Configure periodic package inventory refresh interval
 

controls/update_def.cf.in

@@ -125,6 +125,15 @@ bundle common update_def
     # enable_cfengine_enterprise_hub_ha is defined below
     # Disabled by default
 
+      # If we want to use the backup repository for update (because the class is
+      # defined) and if the location is not already configured (via Augments),
+      # set a default.
+
+      "control_agent_default_repository" -> { "ENT-10481" }
+        string => "$(sys.workdir)/backups",
+        if => and( "mpf_update_control_agent_default_repository",
+                   not( isvariable( "control_agent_default_repository" ) ) );
+
     enable_cfengine_enterprise_hub_ha::
       "standby_servers" slist => filter("$(sys.policy_hub)", "ha_def.ips", false, true, 10);
       "policy_servers" slist => { "$(sys.policy_hub)", "@(standby_servers)" };

update.cf

@@ -158,6 +158,12 @@ body agent control
 
         agentfacility => "$(default:update_def.control_agent_agentfacility)";
 
+    mpf_update_control_agent_default_repository::
+
+      # Location to backup files before they are edited by cfengine
+
+        default_repository => "$(update_def.control_agent_default_repository)";
+
 }
 
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