1 files changed, 104 insertions, 0 deletions
diff --git a/danger/saas_feature/Dangerfile b/danger/saas_feature/Dangerfile
new file mode 100644
index 00000000000..5b1eed7078c
--- /dev/null
+++ b/danger/saas_feature/Dangerfile
@@ -0,0 +1,104 @@
+# frozen_string_literal: true
+
+# rubocop:disable Style/SignalException
+
+SEE_DOC = "see the [SaaS feature documentation](https://docs.gitlab.com/ee/development/ee_features.html#saas-only-feature)."
+LABEL = "saas_feature"
+EXISTS_LABEL = "#{LABEL}::exists".freeze
+SKIPPED_LABEL = "#{LABEL}::skipped".freeze
+
+SUGGEST_MR_COMMENT = <<~SUGGEST_COMMENT.freeze
+  ```suggestion
+  group: "%<group>s"
+  ```
+
+  #{SEE_DOC.capitalize}
+SUGGEST_COMMENT
+
+ENFORCEMENT_WARNING = <<~WARNING_MESSAGE.freeze
+  There were no new or modified SaaS feature YAML files detected in this MR.
+
+  For guidance on when to use a SaaS feature, please #{SEE_DOC}
+WARNING_MESSAGE
+
+def check_yaml(saas_feature)
+  mr_group_label = helper.group_label
+
+  message_for_missing_group!(saas_feature: saas_feature, mr_group_label: mr_group_label) if saas_feature.group.nil?
+rescue Psych::Exception
+  # YAML could not be parsed, fail the build.
+  fail "#{helper.html_link(saas_feature.path)} isn't valid YAML! #{SEE_DOC.capitalize}"
+rescue StandardError => e
+  warn "There was a problem trying to check the SaaS feature file. Exception: #{e.class.name} - #{e.message}"
+end
+
+def message_for_missing_group!(saas_feature:, mr_group_label:)
+  mr_line = saas_feature.raw.lines.find_index do |line|
+    line.start_with?('group:')
+  end
+
+  if mr_line
+    markdown(format(SUGGEST_MR_COMMENT, group: mr_group_label), file: saas_feature.path, line: mr_line.succ)
+  elsif mr_group_label
+    warn %(
+    Consider setting `group: "#{mr_group_label}"` in #{helper.html_link(saas_feature.path)}. #{SEE_DOC.capitalize}
+    )
+  else
+    warn "Consider setting `group` in #{helper.html_link(saas_feature.path)}. #{SEE_DOC.capitalize}"
+  end
+end
+
+def message_for_group!(saas_feature:, mr_group_label:)
+  return if saas_feature.group_match_mr_label?(mr_group_label)
+
+  if mr_group_label
+    fail %(`group` is set to ~"#{saas_feature.group}" in #{helper.html_link(saas_feature.path)},
+            which does not match ~"#{mr_group_label}" set on the MR!)
+  end
+
+  helper.labels_to_add << saas_feature.group
+end
+
+def added_files
+  saas_feature.files(change_type: :added)
+end
+
+def modified_files
+  saas_feature.files(change_type: :modified)
+end
+
+def file_added?
+  added_files.any?
+end
+
+def file_modified?
+  modified_files.any?
+end
+
+def file_added_or_modified?
+  file_added? || file_modified?
+end
+
+def mr_has_backend_or_frontend_changes?
+  changes = helper.changes_by_category
+  changes.has_key?(:backend) || changes.has_key?(:frontend)
+end
+
+def mr_missing_status_label?
+  helper.mr_labels.none? { |label| label.start_with?(LABEL) }
+end
+
+added_files.each do |saas_feature|
+  check_yaml(saas_feature)
+end
+
+if !helper.security_mr? && mr_has_backend_or_frontend_changes?
+  if file_added_or_modified? && !helper.mr_has_labels?(EXISTS_LABEL)
+    # SaaS feature config file touched in this MR, so let's add the label to avoid the warning.
+    helper.labels_to_add << EXISTS_LABEL
+  end
+
+  warn ENFORCEMENT_WARNING if mr_missing_status_label?
+end
+
+# rubocop:enable Style/SignalException