2 files changed, 41 insertions, 0 deletions
diff --git a/lib/tasks/downtime_check.rake b/lib/tasks/downtime_check.rake
new file mode 100644
index 00000000000..30a2e9be5ce
--- /dev/null
+++ b/lib/tasks/downtime_check.rake
@@ -0,0 +1,26 @@
+desc 'Checks if migrations in a branch require downtime'
+task downtime_check: :environment do
+  # First we'll want to make sure we're comparing with the right upstream
+  # repository/branch.
+  current_branch = `git rev-parse --abbrev-ref HEAD`.strip
+
+  # Either the developer ran this task directly on the master branch, or they're
+  # making changes directly on the master branch.
+  if current_branch == 'master'
+    if defined?(Gitlab::License)
+      repo = 'gitlab-ee'
+    else
+      repo = 'gitlab-ce'
+    end
+
+    `git fetch https://gitlab.com/gitlab-org/#{repo}.git --depth 1`
+
+    compare_with = 'FETCH_HEAD'
+  # The developer is working on a different branch, in this case we can just
+  # compare with the master branch.
+  else
+    compare_with = 'master'
+  end
+
+  Rake::Task['gitlab:db:downtime_check'].invoke(compare_with)
+end
diff --git a/lib/tasks/gitlab/db.rake b/lib/tasks/gitlab/db.rake
index 7230b9485be..0ec19e1a625 100644
--- a/lib/tasks/gitlab/db.rake
+++ b/lib/tasks/gitlab/db.rake
@@ -46,5 +46,20 @@ namespace :gitlab do
         Rake::Task['db:seed_fu'].invoke
       end
     end
+
+    desc 'Checks if migrations require downtime or not'
+    task :downtime_check, [:ref] => :environment do |_, args|
+      abort 'You must specify a Git reference to compare with' unless args[:ref]
+
+      require 'shellwords'
+
+      ref = Shellwords.escape(args[:ref])
+
+      migrations = `git diff #{ref}.. --name-only -- db/migrate`.lines.
+        map { |file| Rails.root.join(file.strip).to_s }.
+        select { |file| File.file?(file) }
+
+      Gitlab::DowntimeCheck.new.check_and_print(migrations)
+    end
   end
 end