Remove usage of DockerClient from execution_environments_controller.rb

app/controllers/execution_environments_controller.rb

@@ -133,12 +133,12 @@ class ExecutionEnvironmentsController < ApplicationController
   end
 
   def set_docker_images
-    DockerClient.check_availability!
-    @docker_images = DockerClient.image_tags.sort
-  rescue DockerClient::Error => e
-    @docker_images = []
+    @docker_images ||= ExecutionEnvironment.pluck(:docker_image)
+    @docker_images += Runner.strategy_class.available_images
+  rescue Runner::Error::InternalServerError => e
     flash[:warning] = e.message
-    Sentry.capture_exception(e)
+  ensure
+    @docker_images = @docker_images.sort.uniq
   end
   private :set_docker_images
 

lib/runner/strategy.rb

@@ -9,6 +9,10 @@ class Runner::Strategy
     raise NotImplementedError
   end
 
+  def self.available_images
+    raise NotImplementedError
+  end
+
   def self.sync_environment(_environment)
     raise NotImplementedError
   end

lib/runner/strategy/docker_container_pool.rb

@@ -8,6 +8,13 @@ class Runner::Strategy::DockerContainerPool < Runner::Strategy
     @config ||= CodeOcean::Config.new(:docker).read(erb: true)
   end
 
+  def self.available_images
+    DockerClient.check_availability!
+    DockerClient.image_tags
+  rescue DockerClient::Error => e
+    raise Runner::Error::InternalServerError.new(e.message)
+  end
+
   def self.sync_environment(_environment)
     # There is no dedicated sync mechanism yet
     true

lib/runner/strategy/poseidon.rb

@@ -13,6 +13,13 @@ class Runner::Strategy::Poseidon < Runner::Strategy
     @config ||= CodeOcean::Config.new(:code_ocean).read[:runner_management] || {}
   end
 
+  def self.available_images
+    # Images are pulled when needed for a new execution environment
+    # and cleaned up automatically if no longer in use.
+    # Hence, there is no additional image that we need to return
+    []
+  end
+
   def self.headers
     @headers ||= {'Content-Type' => 'application/json', 'Poseidon-Token' => config[:token]}
   end

spec/controllers/execution_environments_controller_spec.rb

@@ -114,6 +114,7 @@ describe ExecutionEnvironmentsController do
       let(:docker_images) { [1, 2, 3] }
 
       before do
+        allow(Runner).to receive(:strategy_class).and_return Runner::Strategy::DockerContainerPool
         allow(DockerClient).to receive(:check_availability!).at_least(:once)
         allow(DockerClient).to receive(:image_tags).and_return(docker_images)
         controller.send(:set_docker_images)
@@ -126,6 +127,7 @@ describe ExecutionEnvironmentsController do
       let(:error_message) { 'Docker is unavailable' }
 
       before do
+        allow(Runner).to receive(:strategy_class).and_return Runner::Strategy::DockerContainerPool
         allow(DockerClient).to receive(:check_availability!).at_least(:once).and_raise(DockerClient::Error.new(error_message))
         controller.send(:set_docker_images)
       end