1 files changed, 16 insertions, 4 deletions
diff --git a/lib/gitlab/ci/variables/collection.rb b/lib/gitlab/ci/variables/collection.rb
index e2a8af9c26b..ef9ba1b73c7 100644
--- a/lib/gitlab/ci/variables/collection.rb
+++ b/lib/gitlab/ci/variables/collection.rb
@@ -24,6 +24,10 @@ module Gitlab
           self
         end
 
+        def compact
+          Collection.new(select { |variable| !variable.value.nil? })
+        end
+
         def concat(resources)
           return self if resources.nil?
 
@@ -64,11 +68,19 @@ module Gitlab
         end
 
         def expand_value(value, keep_undefined: false)
-          value.gsub(ExpandVariables::VARIABLES_REGEXP) do
+          value.gsub(Item::VARIABLES_REGEXP) do
             match = Regexp.last_match
-            result = @variables_by_key[match[1] || match[2]]&.value
-            result ||= match[0] if keep_undefined
-            result
+            if match[:key]
+              # we matched variable
+              if variable = @variables_by_key[match[:key]]
+                variable.value
+              elsif keep_undefined
+                match[0]
+              end
+            else
+              # we escape sequence
+              match[0]
+            end
           end
         end