MR labels to be inherited from issues it closes

If the issue this MR will close through either the commit messages or
the description have relevant labels, apply them on the MR too.

Closes https://gitlab.com/gitlab-org/gitaly/issues/1555

1 files changed, 14 insertions, 2 deletions

diff --git a/danger/labels/Dangerfile b/danger/labels/Dangerfile
index cd27a323b..6770b718c 100644
--- a/danger/labels/Dangerfile
+++ b/danger/labels/Dangerfile
@@ -5,7 +5,7 @@ def changelog_entry
 
       YAML.safe_load(File.read(file))
     rescue
-      # The changelog danger file will handle this
+      # The change log danger file will handle this
       {}
     end
 end
@@ -30,12 +30,24 @@ TYPE_TO_LABEL = {
   nil => []
 }
 
+INHERIRABLE_LABELS = TYPE_TO_LABEL.values.flatten +  %w[Deliverable]
+
+def inherited_labels
+  gitlab.api
+    .merge_request_closes_issues( gitlab.mr_json['project_id'], gitlab.mr_json['iid'])
+    .flat_map { |i| i.labels }
+    .compact
+    .uniq
+    .select { |label| INHERIRABLE_LABELS.include?(label) }
+end
+
 required_labels.concat(TYPE_TO_LABEL[changelog_entry["type"]])
 
+mr_labels = gitlab.mr_labels | required_labels |inherited_labels
 gitlab.api.update_merge_request(
   gitlab.mr_json['project_id'],
   gitlab.mr_json['iid'],
-  labels: (gitlab.mr_labels | required_labels).join(",")
+  labels: mr_labels.join(",")
 )
 
 # vim: ft=ruby