feat: add ZFS facts to prevent zpool disk changes (#410)

- add zfs_zpools and zfs_datasets facts to detect existing ZFS resources
- skip zpool creation when pools already exist

Reviewed-on: #410

modules/zfs/lib/facter/zfs_datasets.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+Facter.add(:zfs_datasets) do
+  confine kernel: 'Linux'
+  setcode do
+    datasets = []
+
+    if Facter::Core::Execution.which('zfs')
+      begin
+        output = Facter::Core::Execution.execute('zfs list -H -o name 2>/dev/null', on_fail: nil)
+        datasets = output.strip.split("\n") if output && !output.empty?
+      rescue StandardError => e
+        Facter.debug("Error getting zfs dataset information: #{e.message}")
+      end
+    end
+
+    datasets.empty? ? nil : datasets
+  end
+end

modules/zfs/lib/facter/zfs_zpools.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+Facter.add(:zfs_zpools) do
+  confine kernel: 'Linux'
+  setcode do
+    zpools = []
+
+    if Facter::Core::Execution.which('zpool')
+      begin
+        output = Facter::Core::Execution.execute('zpool list -H -o name 2>/dev/null', on_fail: nil)
+        zpools = output.strip.split("\n") if output && !output.empty?
+      rescue StandardError => e
+        Facter.debug("Error getting zpool information: #{e.message}")
+      end
+    end
+
+    zpools.empty? ? nil : zpools
+  end
+end

modules/zfs/manifests/init.pp

@@ -38,8 +38,11 @@ class zfs (
 
   # create zpools
   $zpools.each | $zpool, $data | {
-    zpool { $zpool:
+    # Only create zpool if it doesn't already exist
-      * => $data
+    if $facts['zfs_zpools'] == undef or !($zpool in $facts['zfs_zpools']) {
+      zpool { $zpool:
+        * => $data
+      }
     }
   }