1 files changed, 60 insertions, 0 deletions
diff --git a/danger/changelog/Dangerfile b/danger/changelog/Dangerfile
new file mode 100644
index 000000000..af8e6b93d
--- /dev/null
+++ b/danger/changelog/Dangerfile
@@ -0,0 +1,60 @@
+require 'yaml'
+
+NO_CHANGELOG_LABELS = %w[backstage Documentation test].freeze
+CREATE_CHANGELOG_MESSAGE = <<~MSG.freeze
+You can create one with:
+
+```
+_support/changelog -m %<mr_iid>s "%<mr_title>s"
+```
+
+If your merge request doesn't warrant a CHANGELOG entry,
+consider adding any of the %<labels>s labels.
+MSG
+
+def check_changelog(path)
+  yaml = YAML.safe_load(File.read(path))
+
+  fail "`title` should be set, in #{gitlab.html_link(path)}! #{SEE_DOC}" if yaml["title"].nil?
+  fail "`type` should be set, in #{gitlab.html_link(path)}! #{SEE_DOC}" if yaml["type"].nil?
+
+  if yaml["merge_request"].nil?
+    message "Consider setting `merge_request` to #{gitlab.mr_json["iid"]} in #{gitlab.html_link(path)}. #{SEE_DOC}"
+  elsif yaml["merge_request"] != gitlab.mr_json["iid"]
+    fail "Merge request ID was not set to #{gitlab.mr_json["iid"]}! #{SEE_DOC}"
+  end
+
+  if yaml["type"].nil?
+    fail "No type was set in the changelog"
+  end
+rescue Psych::SyntaxError, Psych::DisallowedClass, Psych::BadAlias
+  # YAML could not be parsed, fail the build.
+  fail "#{gitlab.html_link(path)} isn't valid YAML! #{SEE_DOC}"
+rescue StandardError => e
+  warn "There was a problem trying to check the Changelog. Exception: #{e.name} - #{e.message}"
+end
+
+def presented_no_changelog_labels
+  NO_CHANGELOG_LABELS.map { |label| "~#{label}" }.join(', ')
+end
+
+changelog_needed = (gitlab.mr_labels & NO_CHANGELOG_LABELS).empty?
+changelog_found = git.added_files.find { |path| path =~ %r{\Achangelogs/unreleased/} }
+
+mr_title = gitlab.mr_json["title"].gsub(/^WIP: */, '')
+
+if git.modified_files.include?("CHANGELOG.md")
+  fail "**CHANGELOG.md was edited.** Please remove the additions and create a CHANGELOG entry.\n\n" +
+    format(CREATE_CHANGELOG_MESSAGE, mr_iid: gitlab.mr_json["iid"], mr_title: mr_title, labels: presented_no_changelog_labels)
+end
+
+if changelog_needed
+  if changelog_found
+    check_changelog(changelog_found)
+  else
+    warn "**[CHANGELOG missing](https://docs.gitlab.com/ce/development/changelog.html).**\n\n" +
+      format(CREATE_CHANGELOG_MESSAGE, mr_iid: gitlab.mr_json["iid"], mr_title: mr_title, labels: presented_no_changelog_labels)
+  end
+end
+
+# vim: ft=ruby