Add strategy for DockerContainerPool

In order to provide an alternative to Poseidon, a strategy for the
DockerContainerPool is added that is used by the runner model.

Co-authored-by: Sebastian Serth <Sebastian.Serth@hpi.de>

lib/runner/strategy/docker_container_pool.rb

@@ -0,0 +1,138 @@
+# frozen_string_literal: true
+
+class Runner::Strategy::DockerContainerPool < Runner::Strategy
+  attr_reader :container_id, :command, :execution_environment
+
+  def self.config
+    # Since the docker configuration file contains code that must be executed, we use ERB templating.
+    @config ||= CodeOcean::Config.new(:docker).read(erb: true)
+  end
+
+  def self.request_from_management(environment)
+    container_id = JSON.parse(Faraday.get("#{config[:pool][:location]}/docker_container_pool/get_container/#{environment.id}").body)['id']
+    container_id.presence || raise(Runner::Error::NotAvailable.new("DockerContainerPool didn't return a container id"))
+  rescue Faraday::Error => e
+    raise Runner::Error::Unknown.new("Faraday request to DockerContainerPool failed: #{e.inspect}")
+  rescue JSON::ParserError => e
+    raise Runner::Error::Unknown.new("DockerContainerPool returned invalid JSON: #{e.inspect}")
+  end
+
+  def initialize(runner_id, _environment)
+    super
+    @container_id = runner_id
+  end
+
+  def copy_files(files)
+    FileUtils.mkdir_p(local_workspace_path)
+    clean_workspace
+    files.each do |file|
+      if file.path.present?
+        local_directory_path = local_path(file.path)
+        FileUtils.mkdir_p(local_directory_path)
+      end
+
+      local_file_path = local_path(file.filepath)
+      if file.file_type.binary?
+        FileUtils.cp(file.native_file.path, local_file_path)
+      else
+        begin
+          File.open(local_file_path, 'w') {|f| f.write(file.content) }
+        rescue IOError => e
+          # TODO: try catch i/o exception and log failed attempts
+          # Does this fix the issue @Sebastian? What exceptions did you have in mind?
+          raise Runner::Error::Unknown.new("Could not create workspace file #{file.filepath}: #{e.inspect}")
+        end
+      end
+    end
+    FileUtils.chmod_R('+rwX', local_workspace_path)
+  end
+
+  def destroy_at_management
+    Faraday.get("#{self.class.config[:pool][:location]}/docker_container_pool/destroy_container/#{container.id}")
+  rescue Faraday::Error => e
+    raise Runner::Error::Unknown.new("Faraday request to DockerContainerPool failed: #{e.inspect}")
+  end
+
+  def attach_to_execution(command)
+    @command = command
+    starting_time = Time.zone.now
+    query_params = 'logs=0&stream=1&stderr=1&stdout=1&stdin=1'
+    websocket_url = "#{self.class.config[:ws_host]}/v1.27/containers/#{@container_id}/attach/ws?#{query_params}"
+
+    EventMachine.run do
+      socket = Connection.new(websocket_url, self)
+      EventMachine.add_timer(@execution_environment.permitted_execution_time) do
+        socket.status = :timeout
+        destroy_at_management
+      end
+      socket.send(command)
+      yield(socket)
+    end
+    Time.zone.now - starting_time # execution duration in seconds
+  end
+
+  private
+
+  def container
+    return @container if @container.present?
+
+    @container = Docker::Container.get(@container_id)
+    raise Runner::Error::RunnerNotFound unless @container.info['State']['Running']
+
+    @container
+  rescue Docker::Error::NotFoundError
+    raise Runner::Error::RunnerNotFound
+  end
+
+  def local_path(path)
+    unclean_path = local_workspace_path.join(path)
+    clean_path = File.expand_path(unclean_path)
+    unless clean_path.to_s.start_with? local_workspace_path.to_s
+      raise Runner::Error::Unknown.new("Local filepath #{clean_path.inspect} not allowed")
+    end
+
+    Pathname.new(clean_path)
+  end
+
+  def clean_workspace
+    FileUtils.rm_r(local_workspace_path.children, secure: true)
+  rescue Errno::ENOENT => e
+    raise Runner::Error::Unknown.new("The workspace directory does not exist and cannot be deleted: #{e.inspect}")
+  rescue Errno::EACCES => e
+    # TODO: Why was this rescued before @Sebastian?
+    raise Runner::Error::Unknown.new("Not allowed to clean workspace #{local_workspace_path}: #{e.inspect}")
+  end
+
+  def local_workspace_path
+    @local_workspace_path ||= Pathname.new(container.binds.first.split(':').first)
+  end
+
+  class Connection < Runner::Connection
+    def initialize(*args)
+      @stream = 'stdout'
+      super
+    end
+
+    def encode(data)
+      "#{data}\n"
+    end
+
+    def decode(raw_event)
+      case raw_event.data
+        when /@#{@strategy.container_id[0..11]}/
+          # Assume correct termination for now and return exit code 0
+          # TODO: Can we use the actual exit code here?
+          @exit_code = 0
+          @status = :terminated
+          @socket.close
+        when /#{format(@strategy.execution_environment.test_command, class_name: '.*', filename: '.*', module_name: '.*')}/
+          # TODO: Super dirty hack to redirect test output to stderr (remove attr_reader afterwards)
+          @stream = 'stderr'
+        when /#{@strategy.command}/
+        when /bash: cmd:canvasevent: command not found/
+        else
+          {'type' => @stream, 'data' => raw_event.data}
+      end
+    end
+  end
+end