Implement resource limits

lib/coursemology/evaluator.rb

@@ -13,6 +13,7 @@ module Coursemology::Evaluator
   extend ActiveSupport::Autoload
 
   autoload :Client
+  autoload :DockerContainer
   autoload :CLI
   autoload :Models
   autoload :Services

lib/coursemology/evaluator/docker_container.rb

@@ -0,0 +1,31 @@
+class Coursemology::Evaluator::DockerContainer < Docker::Container
+  class << self
+    def create(image, argv: nil)
+      pull_image(image)
+
+      ActiveSupport::Notifications.instrument('create.docker.evaluator.coursemology',
+                                              image: image) do |payload|
+        options = { 'Image' => image }
+        options['Cmd'] = argv if argv && !argv.empty?
+
+        payload[:container] = super(options)
+      end
+    end
+
+    private
+
+    def pull_image(image)
+      ActiveSupport::Notifications.instrument('pull.docker.evaluator.coursemology',
+                                              image: image) do
+        Docker::Image.create('fromImage' => image)
+      end
+    end
+  end
+
+  def delete
+    ActiveSupport::Notifications.instrument('destroy.docker.evaluator.coursemology',
+                                            container: id) do
+      super
+    end
+  end
+end

lib/coursemology/evaluator/services/evaluate_programming_package_service.rb

@@ -10,6 +10,9 @@ class Coursemology::Evaluator::Services::EvaluateProgrammingPackageService
   # The path to where the test report will be at.
   REPORT_PATH = File.join(PACKAGE_PATH, 'report.xml')
 
+  # The ratio to multiply the memory limits from our evaluation to the container by.
+  MEMORY_LIMIT_RATIO = 1.megabyte / 1.kilobyte
+
   # Executes the given package in a container.
   #
   # @param [Coursemology::Evaluator::Models::ProgrammingEvaluation] evaluation The evaluation
@@ -43,15 +46,15 @@ def execute
 
   def create_container(image)
     image_identifier = "coursemology/evaluator-image-#{image}"
-    ActiveSupport::Notifications.instrument('pull.docker.evaluator.coursemology',
-                                            image: image_identifier) do
-      Docker::Image.create('fromImage' => image_identifier)
-    end
+    Coursemology::Evaluator::DockerContainer.create(image_identifier, argv: container_arguments)
+  end
 
-    ActiveSupport::Notifications.instrument('create.docker.evaluator.coursemology',
-                                            image: image_identifier) do |payload|
-      payload[:container] = Docker::Container.create('Image' => image_identifier)
-    end
+  def container_arguments
+    result = []
+    result.push("-c#{@evaluation.time_limit}") if @evaluation.time_limit
+    result.push("-m#{@evaluation.memory_limit * MEMORY_LIMIT_RATIO}") if @evaluation.memory_limit
+
+    result
   end
 
   # Copies the contents of the package to the container.
@@ -156,9 +159,6 @@ def extract_test_report_archive(container)
   end
 
   def destroy_container(container)
-    ActiveSupport::Notifications.instrument('destroy.docker.evaluator.coursemology',
-                                            container: container.id) do
-      container.delete
-    end
+    container.delete
   end
 end

spec/coursemology/evaluator/docker_container_spec.rb

@@ -0,0 +1,20 @@
+RSpec.describe Coursemology::Evaluator::DockerContainer do
+  let(:image) { 'coursemology/evaluator-image-python:2.7' }
+  subject { Coursemology::Evaluator::DockerContainer.create(image) }
+
+  describe '.create' do
+    it 'instruments the pull' do
+      expect { subject }.to instrument_notification('pull.docker.evaluator.coursemology')
+    end
+
+    it 'instruments the creation' do
+      expect { subject }.to instrument_notification('create.docker.evaluator.coursemology')
+    end
+  end
+
+  describe '#delete' do
+    it 'instruments the destruction' do
+      expect { subject.delete }.to instrument_notification('destroy.docker.evaluator.coursemology')
+    end
+  end
+end

spec/coursemology/evaluator/services/evaluate_programming_package_service_spec.rb

@@ -1,7 +1,9 @@
 require 'spec_helper'
 
 RSpec.describe Coursemology::Evaluator::Services::EvaluateProgrammingPackageService do
-  let(:package) { build(:programming_evaluation) }
+  let(:package) { build(:programming_evaluation, *package_params) }
+  let(:package_params) { nil }
+  let(:image) { 'python:2.7' }
   subject { Coursemology::Evaluator::Services::EvaluateProgrammingPackageService.new(package) }
 
   describe '.execute' do
@@ -12,27 +14,26 @@
   end
 
   describe '#create_container' do
-    let(:image) { 'python:2.7' }
     let(:container) { subject.send(:create_container, image) }
 
     it 'prefixes the image with coursemology/evaluator-image' do
-      expect(Docker::Image).to \
-        receive(:create).with('fromImage' => "coursemology/evaluator-image-#{image}").
-        and_call_original
-      expect(Docker::Container).to \
-        receive(:create).with('Image' => "coursemology/evaluator-image-#{image}")
+      expect(Coursemology::Evaluator::DockerContainer).to \
+        receive(:create).with("coursemology/evaluator-image-#{image}",
+                              hash_including(argv: []))
 
       container
     end
 
-    it 'instruments the pull' do
-      expect { subject.send(:create_container, image) }.to \
-        instrument_notification('pull.docker.evaluator.coursemology')
-    end
+    context 'when the evaluation has resource limits' do
+      let(:package_params) { [time_limit: 5, memory_limit: 16]  }
+
+      it 'specifies them to the container' do
+        expect(Coursemology::Evaluator::DockerContainer).to \
+          receive(:create).with("coursemology/evaluator-image-#{image}",
+                                hash_including(argv: ['-c5', '-m16384']))
 
-    it 'instruments the creation' do
-      expect { subject.send(:create_container, image) }.to \
-        instrument_notification('create.docker.evaluator.coursemology')
+        subject.send(:create_container, image)
+      end
     end
   end
 
@@ -62,7 +63,6 @@
   end
 
   describe '#execute_package' do
-    let(:image) { 'python:2.7' }
     let(:container) { subject.send(:create_container, image) }
     after { subject.send(:destroy_container, container) }
 
@@ -83,7 +83,6 @@ def evaluate_result
   end
 
   describe '#execute_package_wait' do
-    let(:image) { 'python:2.7' }
     let(:container) { subject.send(:create_container, image) }
     after { subject.send(:destroy_container, container) }
 
@@ -101,7 +100,6 @@ def evaluate_result
   end
 
   describe '#extract_result' do
-    let(:image) { 'python:2.7' }
     let(:container) do
       subject.send(:create_container, image).tap do |container|
         subject.send(:execute_package, container)
@@ -117,7 +115,6 @@ def evaluate_result
   end
 
   describe '#extract_test_report' do
-    let(:image) { 'python:2.7' }
     let(:report_path) { File.join(__dir__, '../../../fixtures/sample_report.xml') }
     let(:report_contents) { File.read(report_path) }
     let(:container) { subject.send(:create_container, image) }
@@ -144,14 +141,4 @@ def copy_dummy_report
       end
     end
   end
-
-  describe '#destroy_container' do
-    let(:image) { 'python:2.7' }
-    let(:container) { subject.send(:create_container, image) }
-
-    it 'instruments the destruction' do
-      expect { subject.send(:destroy_container, container) }.to \
-        instrument_notification('destroy.docker.evaluator.coursemology')
-    end
-  end
 end

spec/factories/programming_evaluations.rb

@@ -10,8 +10,8 @@ def self.define_package(evaluation)
   factory :programming_evaluation, class: Coursemology::Evaluator::Models::ProgrammingEvaluation do
     id 1
     language Coursemology::Polyglot::Language::Python::Python2Point7.name
-    memory_limit 32
-    time_limit 5
+    memory_limit nil
+    time_limit nil
 
     after(:stub) do |evaluation|
       evaluation.define_singleton_method(:save) {}