From 96bfd3edb1e78b3ecebf3b8673277ce3f6a96f62 Mon Sep 17 00:00:00 2001
From: Josh Cooper <joshcooper@users.noreply.github.com>
Date: Thu, 16 May 2024 10:52:55 -0700
Subject: [PATCH] Knockout prefix reproduction

---
 examples/hiera/data/common.yaml     | 4 +++-
 examples/hiera/data/dc1.yaml        | 1 +
 examples/hiera/data/production.yaml | 2 ++
 examples/hiera/hiera.yaml           | 6 ++++--
 lib/puppet/pops/merge_strategy.rb   | 4 +++-
 5 files changed, 13 insertions(+), 4 deletions(-)
 create mode 100644 examples/hiera/data/production.yaml

diff --git a/examples/hiera/data/common.yaml b/examples/hiera/data/common.yaml
index 693fb02b70a..425bcd5bb51 100644
--- a/examples/hiera/data/common.yaml
+++ b/examples/hiera/data/common.yaml
@@ -9,4 +9,6 @@ ntp::config::ntpservers:
 
 lookup_options:
   classes:
-    merge: unique
+    merge:
+      strategy: deep
+      knockout_prefix: --
diff --git a/examples/hiera/data/dc1.yaml b/examples/hiera/data/dc1.yaml
index 4aa3a476cbc..a113c75d8a7 100644
--- a/examples/hiera/data/dc1.yaml
+++ b/examples/hiera/data/dc1.yaml
@@ -3,4 +3,5 @@ ntp::config::ntpservers:
   - 'ntp1.dc1.example.com'
   - 'ntp2.dc1.example.com'
 classes:
+  - --ntp::config
   - users::dc1
diff --git a/examples/hiera/data/production.yaml b/examples/hiera/data/production.yaml
new file mode 100644
index 00000000000..b94e4f0de80
--- /dev/null
+++ b/examples/hiera/data/production.yaml
@@ -0,0 +1,2 @@
+---
+classes:
diff --git a/examples/hiera/hiera.yaml b/examples/hiera/hiera.yaml
index 09d46a91301..5ec287d3541 100644
--- a/examples/hiera/hiera.yaml
+++ b/examples/hiera/hiera.yaml
@@ -6,10 +6,12 @@ defaults:
 
 hierarchy:
   - name: 'Per Location'
-    path: "%{facts.location}.yaml"
+    path: 'dc1.yaml'
+    #%{facts.location}.yaml"
 
   - name: 'Per Environment'
-    path: "%{facts.environment}.yaml"
+    path: 'production.yaml' 
+    # path: "%{facts.environment}.yaml"
 
   - name: 'Common Data'
     path: 'common.yaml'
diff --git a/lib/puppet/pops/merge_strategy.rb b/lib/puppet/pops/merge_strategy.rb
index c79d445e051..f78537132ef 100644
--- a/lib/puppet/pops/merge_strategy.rb
+++ b/lib/puppet/pops/merge_strategy.rb
@@ -373,7 +373,9 @@ def checked_merge(e1, e2)
       dm_options = { :preserve_unmergeables => false }
       options.each_pair { |k, v| dm_options[k.to_sym] = v unless k == 'strategy' }
       # e2 (the destination) is deep cloned to avoid that the passed in object mutates
-      DeepMerge.deep_merge!(e1, deep_clone(e2), dm_options)
+      rval = DeepMerge.deep_merge!(e1, deep_clone(e2), dm_options)
+      puts "Merging #{e1.inspect} with #{e2.inspect} result #{rval.inspect}"
+      rval
     end
 
     def deep_clone(value)