added option to recycle Docker containers

lib/docker_client.rb

@@ -5,6 +5,7 @@ class DockerClient
   DEFAULT_MEMORY_LIMIT = 256
   LOCAL_WORKSPACE_ROOT = Rails.root.join('tmp', 'files', Rails.env)
   MINIMUM_MEMORY_LIMIT = 4
+  RECYCLE_CONTAINERS = true
   RETRY_COUNT = 2
 
   attr_reader :container
@@ -155,19 +156,19 @@ class DockerClient
     `docker pull #{docker_image}` if docker_image
   end
 
-  #this sends the command to run whatever is defined in the backend
+  def return_container(container)
+    local_workspace_path = self.class.local_workspace_path(container)
+    FileUtils.rm_rf(local_workspace_path) if local_workspace_path
+    FileUtils.mkdir(local_workspace_path)
+    DockerContainerPool.return_container(container, @execution_environment)
+  end
+  private :return_container
+
   def send_command(command, container, &block)
     Timeout.timeout(@execution_environment.permitted_execution_time.to_i) do
       stderr = []
       stdout = []
-      # map command in a shell call, maybe add -c
-      command =  ['bash', '-c', command]
-      #command.join!(' ')
-      # lets call the command, but we do not want the container to stop afterwards
-      # thats why we use exec. If its ok do stop the container this could be assign instead
-      container.exec(command) do |stream, chunk|
-      #container.attach(stdin: StringIO.new(command)) do |stream, chunk|
-
+      container.exec(['bash', '-c', command]) do |stream, chunk|
         block.call(stream, chunk) if block_given?
         if stream == :stderr
           stderr.push(chunk)
@@ -180,16 +181,7 @@ class DockerClient
   rescue Timeout::Error
     {status: :timeout}
   ensure
-    Concurrent::Future.execute {
-      # If you do not want to reuse running container you could use:
-      #self.class.destroy_container(container)
-      # This could be moved to an execution environment specific setting
-
-      # we may need to stop the exec call here..!!!
-      FileUtils.rm_rf(local_workspace_path(container)) if local_workspace_path(container)
-      FileUtils.mkdir(local_workspace_path)
-      DockerContainerPool.return_container(container, @execution_environment)
-    }
+    RECYCLE_CONTAINERS ? return_container(container) : self.class.destroy_container(container)
   end
   private :send_command