transferred Code Ocean from original repository to GitHub

lib/tasks/docker.rake

@@ -0,0 +1,14 @@
+namespace :docker do
+  desc 'List all installed Docker images'
+  task :images => :environment do
+    puts DockerClient.image_tags
+  end
+
+  desc 'Pull all Docker images referenced by execution environments'
+  task :pull => :environment do
+    ExecutionEnvironment.all.map(&:docker_image).each do |docker_image|
+      puts "Pulling #{docker_image}..."
+      DockerClient.pull(docker_image)
+    end
+  end
+end