(PE-40386) alternate avail_group_letter for migration

Author: davidmalloncares

plans/add_database.pp

@@ -61,16 +61,15 @@
   out::message("Operating in ${operating_mode} mode")
 
   if $operating_mode == 'init' {
-    # if we are doing a migration then we need to assign the new node to group A
-    if $is_migration {
-      $avail_group_letter = 'A'
-    } else {
-      # If no other PSQL node then match primary group letter
-      $avail_group_letter = peadm::flatten_compact($roles['server'].map |$k,$v| {
-          if $v == $primary_host {
-            $k
-          }
-      })[0]
+    # If no other PSQL node then match primary group letter
+    $calculated_group_letter = peadm::flatten_compact($roles['server'].map |$k,$v| {
+        if $v == $primary_host {
+          $k
+        }
+    })[0]
+    $avail_group_letter = $calculated_group_letter ? {
+      undef   => $is_migration ? { true => 'A', default => undef },
+      default => $calculated_group_letter,
     }
     # Assume PuppetDB backend hosted on Primary if in init mode
     $source_db_host = $primary_host