danger: Move rules into subdirectory

It's best practice for Danger rules to live in a separate "rules/"
directory. Let's move them there, which also allows us to use globs to
import all rules.

5 files changed, 249 insertions, 0 deletions

diff --git a/danger/rules/changelog/Dangerfile b/danger/rules/changelog/Dangerfile
new file mode 100644
index 000000000..e1079b78a
--- /dev/null
+++ b/danger/rules/changelog/Dangerfile
@@ -0,0 +1,91 @@
+require 'yaml'
+
+def lint_commit(commit)
+  trailer = commit.message.match(/^(?<name>Changelog):\s*(?<category>.+)$/i)
+
+  return :missing if trailer.nil? || trailer[:category].nil?
+
+  name = trailer[:name]
+
+  unless name == 'Changelog'
+    self.fail(
+      "The changelog trailer for commit #{commit.sha} must be `Changelog` (starting with a capital C), not `#{name}`"
+    )
+
+    return :invalid
+  end
+
+  category = trailer[:category]
+
+  return :valid if CATEGORIES.include?(category)
+
+  self.fail(
+    "Commit #{commit.sha} uses an invalid changelog category: #{category}"
+  )
+
+  :invalid
+end
+
+def presented_no_changelog_labels
+  NO_CHANGELOG_LABELS.map { |label| %(~"#{label}") }.join(', ')
+end
+
+NO_CHANGELOG_LABELS = [
+  'documentation',
+  'type::tooling',
+  'tooling::pipelines',
+  'tooling::workflow',
+  'ci-build',
+  'meta'
+].freeze
+
+CATEGORIES = YAML
+  .load_file(File.expand_path('../../../.gitlab/changelog_config.yml', __dir__))
+  .fetch('categories')
+  .keys
+  .freeze
+
+SEE_DOC = "See [the documentation](https://docs.gitlab.com/ee/development/changelog.html).".freeze
+
+CHANGELOG_MISSING = <<~MSG.freeze
+**[CHANGELOG missing](https://docs.gitlab.com/ee/development/changelog.html).**
+
+To ceate a changelog, annotate one or more commits with the `Changelog` Git
+trailer. If you want to annotate the latest commit, you can do so using `git
+commit --amend`. If you want to annotate older or multiple commits, you need to
+do so using `git rebase -i`.
+
+When adding the trailer, you can use the following values:
+
+- #{CATEGORIES.join("\n- ")}
+
+For example:
+
+```
+This is the subject of your commit.
+
+This would be the body of your commit containing some extra details.
+
+Changelog: added
+```
+
+If your merge request doesn't warrant a CHANGELOG entry, consider adding any of
+the #{presented_no_changelog_labels} labels.
+
+#{SEE_DOC}
+MSG
+
+changelog_needed = (gitlab.mr_labels & NO_CHANGELOG_LABELS).empty?
+
+if changelog_needed
+  checked = 0
+
+  git.commits.each do |commit|
+    case lint_commit(commit)
+    when :valid, :invalid
+      checked += 1
+    end
+  end
+
+  warn(CHANGELOG_MISSING) if checked.zero?
+end
diff --git a/danger/rules/labels/Dangerfile b/danger/rules/labels/Dangerfile
new file mode 100644
index 000000000..6bfee7178
--- /dev/null
+++ b/danger/rules/labels/Dangerfile
@@ -0,0 +1,48 @@
+def changelog_entry
+  @changelog_entry ||=
+    begin
+      file = git.added_files.find { |path| path =~ %r{\Achangelogs/unreleased/} }
+
+      YAML.safe_load(File.read(file))
+    rescue
+      # The change log danger file will handle this
+      {}
+    end
+end
+
+required_labels = %w[devops::create]
+required_labels << "group::gitaly" if GITALY_TEAM.include?(gitlab.mr_author)
+
+TYPE_TO_LABEL = {
+  'added' => %w[type::feature feature::addition],
+  'fixed' => ['type::bug'],
+  'changed' => ['type::maintenance'],
+  'deprecated' => ['type::maintenance'],
+  'security' => ['security'],
+  'removed' => ['type::maintenance'],
+  'performance' => %w[type::maintenance performance],
+  'other' => ['type::tooling'],
+  nil => []
+}
+
+INHERITABLE_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| INHERITABLE_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: mr_labels.join(",")
+)
+
+# vim: ft=ruby
diff --git a/danger/rules/merge_request/Dangerfile b/danger/rules/merge_request/Dangerfile
new file mode 100644
index 000000000..b9c81d2af
--- /dev/null
+++ b/danger/rules/merge_request/Dangerfile
@@ -0,0 +1,13 @@
+unless /^([[:alnum:]][[:lower:]]+: )?[[:upper:]]/ =~ gitlab.mr_title
+  warn("Please capitalize the merge request title")
+end
+
+if gitlab.mr_body.empty?
+  fail("Please provide a merge request description")
+end
+
+if gitlab.mr_title.length > 72
+  warn "The title of this merge requests it too long"
+end
+
+# vim: ft=ruby
diff --git a/danger/rules/milestones/Dangerfile b/danger/rules/milestones/Dangerfile
new file mode 100644
index 000000000..ce74bbb87
--- /dev/null
+++ b/danger/rules/milestones/Dangerfile
@@ -0,0 +1,23 @@
+unless gitlab.mr_json["milestone"]
+  issues = gitlab.api.merge_request_closes_issues(gitlab.mr_json['project_id'], gitlab.mr_json['iid'])
+
+  milestone_id = issues
+    .map { |i| i.milestone }
+    .compact
+    .reject { |m| m.state == "closed" || m.due_date.nil? }
+    .sort_by { |m| m.due_date }
+    .first
+    &.id
+
+  if milestone_id
+    gitlab.api.update_merge_request(
+      gitlab.mr_json['project_id'],
+      gitlab.mr_json['iid'],
+      milestone_id: milestone_id
+    )
+  else
+    warn "No milestone was set, nor could it be detected from the issues this merge request closes."
+  end
+end
+
+# vim: ft=ruby
diff --git a/danger/rules/roulette/Dangerfile b/danger/rules/roulette/Dangerfile
new file mode 100644
index 000000000..80ee666df
--- /dev/null
+++ b/danger/rules/roulette/Dangerfile
@@ -0,0 +1,74 @@
+# frozen_string_literal: true
+
+MESSAGE = <<MARKDOWN
+## Reviewer roulette
+
+Changes that require review have been detected! A merge request is normally
+reviewed by both a reviewer and a maintainer in its primary category and by a
+maintainer in all other categories.
+MARKDOWN
+
+CATEGORY_TABLE_HEADER = <<MARKDOWN
+
+To spread load more evenly across eligible reviewers, Danger has picked a candidate for each
+review slot. Feel free to
+[override these selections](https://about.gitlab.com/handbook/engineering/projects/#gitaly)
+if you think someone else would be better-suited
+or use the [GitLab Review Workload Dashboard](https://gitlab-org.gitlab.io/gitlab-roulette/) to find other available reviewers.
+
+To read more on how to use the reviewer roulette, please take a look at the
+[Engineering workflow](https://about.gitlab.com/handbook/engineering/workflow/#basics)
+and [code review guidelines](https://docs.gitlab.com/ee/development/code_review.html).
+Please consider assigning a reviewer or maintainer who is a
+[domain expert](https://about.gitlab.com/handbook/engineering/projects/#gitaly) in the area of the merge request.
+
+Once you've decided who will review this merge request, mention them as you
+normally would! Danger does not automatically notify them for you.
+
+| Category | Reviewer | Maintainer |
+| -------- | -------- | ---------- |
+MARKDOWN
+
+OPTIONAL_REVIEW_TEMPLATE = '%{role} review is optional for %{category}'
+NOT_AVAILABLE_TEMPLATE = 'No %{role} available'
+
+def note_for_spins_role(spins, role)
+  spins.each do |spin|
+    note = note_for_spin_role(spin, role)
+
+    return note if note
+  end
+
+  NOT_AVAILABLE_TEMPLATE % { role: role }
+end
+
+def note_for_spin_role(spin, role)
+  if spin.optional_role == role
+    return OPTIONAL_REVIEW_TEMPLATE % { role: role.capitalize, category: helper.label_for_category(spin.category) }
+  end
+
+  spin.public_send(role)&.markdown_name(author: roulette.team_mr_author) # rubocop:disable GitlabSecurity/PublicSend
+end
+
+def markdown_row_for_spins(category, spins_array)
+  reviewer_note = note_for_spins_role(spins_array, :reviewer)
+  maintainer_note = note_for_spins_role(spins_array, :maintainer)
+
+  "| #{helper.label_for_category(category)} | #{reviewer_note} | #{maintainer_note} |"
+end
+
+changes = project_helper.changes_by_category
+
+if changes.any?
+  categories = changes.keys
+  project = project_helper.project_name
+
+  random_roulette_spins = roulette.spin(project, [nil], timezone_experiment: false)
+
+  rows = random_roulette_spins.map do |spin|
+    markdown_row_for_spins(spin.category, [spin])
+  end
+
+  markdown(MESSAGE)
+  markdown(CATEGORY_TABLE_HEADER + rows.join("\n")) unless rows.empty?
+end