Handle Faraday errors

app/models/execution_environment.rb

@@ -51,6 +51,9 @@ class ExecutionEnvironment < ApplicationRecord
 
     Rails.logger.warn("Could not create execution environment in Poseidon, got response: #{response.as_json}")
     false
+  rescue Faraday::Error => e
+    Rails.logger.warn("Could not create execution environment because of Faraday error: #{e.inspect}")
+    false
   end
 
   def to_json(*_args)

app/models/submission.rb

@@ -197,7 +197,7 @@ class Submission < ApplicationRecord
     runner = Runner.for(user, exercise)
     copy_files_to runner
     waiting_duration = Time.zone.now - request_time
-    yield(runner, waiting_duration) if block_given?
+    yield(runner, waiting_duration)
   end
 
   def command_for(template, file)

spec/lib/runner/strategy/poseidon_spec.rb

@@ -100,6 +100,20 @@ describe Runner::Strategy::Poseidon do
     end
   end
 
+  # All requests handle a Faraday error the same way.
+  shared_examples 'Faraday error handling' do
+    context 'when Faraday throws an error' do
+      # The response status is not needed in this context but the describes block this context is embedded
+      # into expect this variable to be set in order to properly stub requests to the runner management.
+      let(:response_status) { -1 }
+
+      it 'raises an error' do
+        %i[post patch delete].each {|message| allow(Faraday).to receive(message).and_raise(Faraday::TimeoutError) }
+        expect { action.call }.to raise_error(Runner::Error::Unknown, /Faraday/)
+      end
+    end
+  end
+
   describe '::request_from_management' do
     let(:action) { -> { described_class.request_from_management(execution_environment) } }
     let!(:request_runner_stub) do
@@ -158,6 +172,7 @@ describe Runner::Strategy::Poseidon do
 
     include_examples 'InternalServerError (500) error handling'
     include_examples 'unknown response status error handling'
+    include_examples 'Faraday error handling'
   end
 
   describe '#execute_command' do
@@ -213,6 +228,7 @@ describe Runner::Strategy::Poseidon do
     include_examples 'NotFound (404) error handling'
     include_examples 'InternalServerError (500) error handling'
     include_examples 'unknown response status error handling'
+    include_examples 'Faraday error handling'
   end
 
   describe '#destroy_at_management' do
@@ -236,6 +252,7 @@ describe Runner::Strategy::Poseidon do
     include_examples 'NotFound (404) error handling'
     include_examples 'InternalServerError (500) error handling'
     include_examples 'unknown response status error handling'
+    include_examples 'Faraday error handling'
   end
 
   describe '#copy_files' do
@@ -268,6 +285,7 @@ describe Runner::Strategy::Poseidon do
     include_examples 'NotFound (404) error handling'
     include_examples 'InternalServerError (500) error handling'
     include_examples 'unknown response status error handling'
+    include_examples 'Faraday error handling'
   end
 
   describe '#attach_to_execution' do

spec/models/execution_environment_spec.rb

@@ -227,5 +227,10 @@ describe ExecutionEnvironment do
     [400, 500].each do |status|
       include_examples 'returns false when the api request failed', status
     end
+
+    it 'returns false if Faraday raises an error' do
+      allow(Faraday).to receive(:put).and_raise(Faraday::TimeoutError)
+      expect(execution_environment.copy_to_poseidon).to be_falsey
+    end
   end
 end