From 5ba483c68a0c613dbf31a70f432db52acb700c1f Mon Sep 17 00:00:00 2001
From: Ben Vincent <ben@unkin.net>
Date: Sat, 18 Oct 2025 21:24:33 +1100
Subject: [PATCH] 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: https://git.unkin.net/unkin/puppet-prod/pulls/410
---
 modules/zfs/lib/facter/zfs_datasets.rb | 19 +++++++++++++++++++
 modules/zfs/lib/facter/zfs_zpools.rb   | 19 +++++++++++++++++++
 modules/zfs/manifests/init.pp          |  7 +++++--
 3 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 modules/zfs/lib/facter/zfs_datasets.rb
 create mode 100644 modules/zfs/lib/facter/zfs_zpools.rb

diff --git a/modules/zfs/lib/facter/zfs_datasets.rb b/modules/zfs/lib/facter/zfs_datasets.rb
new file mode 100644
index 0000000..ebc01cd
--- /dev/null
+++ b/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
diff --git a/modules/zfs/lib/facter/zfs_zpools.rb b/modules/zfs/lib/facter/zfs_zpools.rb
new file mode 100644
index 0000000..000a653
--- /dev/null
+++ b/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
diff --git a/modules/zfs/manifests/init.pp b/modules/zfs/manifests/init.pp
index 6feeeed..79f95e3 100644
--- a/modules/zfs/manifests/init.pp
+++ b/modules/zfs/manifests/init.pp
@@ -38,8 +38,11 @@ class zfs (
 
   # create zpools
   $zpools.each | $zpool, $data | {
-    zpool { $zpool:
-      * => $data
+    # Only create zpool if it doesn't already exist
+    if $facts['zfs_zpools'] == undef or !($zpool in $facts['zfs_zpools']) {
+      zpool { $zpool:
+        * => $data
+      }
     }
   }