Use Net::HTTP::Persistent for requests to Poseidon

Gemfile

@@ -20,6 +20,7 @@ gem 'json_schemer'
 gem 'js-routes'
 gem 'kramdown'
 gem 'mimemagic'
+gem 'net-http-persistent'
 gem 'nokogiri'
 gem 'pagedown-bootstrap-rails'
 gem 'pg'

Gemfile.lock

@@ -140,6 +140,7 @@ GEM
     chronic (0.10.2)
     coderay (1.1.3)
     concurrent-ruby (1.1.9)
+    connection_pool (2.2.5)
     crack (0.4.5)
       rexml
     crass (1.0.6)
@@ -279,6 +280,8 @@ GEM
     multi_xml (0.6.0)
     multipart-post (2.1.1)
     nested_form (0.3.2)
+    net-http-persistent (4.0.0)
+      connection_pool (~> 2.2)
     netrc (0.11.0)
     newrelic_rpm (8.1.0)
     nio4r (2.5.8)
@@ -574,6 +577,7 @@ DEPENDENCIES
   listen
   mimemagic
   mnemosyne-ruby
+  net-http-persistent
   newrelic_rpm
   nokogiri
   nyan-cat-formatter
@@ -620,4 +624,4 @@ DEPENDENCIES
   whenever
 
 BUNDLED WITH
-   2.2.23
+   2.2.29

lib/runner/strategy/poseidon.rb

@@ -21,8 +21,7 @@ class Runner::Strategy::Poseidon < Runner::Strategy
 
   def self.sync_environment(environment)
     url = "#{config[:url]}/execution-environments/#{environment.id}"
-    connection = Faraday.new nil, ssl: {ca_file: config[:ca_file]}
-    response = connection.put url, environment.to_json, headers
+    response = http_connection.put url, environment.to_json
     return true if [201, 204].include? response.status
 
     Rails.logger.warn("Could not create execution environment in Poseidon, got response: #{response.as_json}")
@@ -39,8 +38,7 @@ class Runner::Strategy::Poseidon < Runner::Strategy
       inactivityTimeout: config[:unused_runner_expiration_time].seconds,
     }
     Rails.logger.debug { "#{Time.zone.now.getutc.inspect}: Requesting new runner at #{url}" }
-    connection = Faraday.new nil, ssl: {ca_file: config[:ca_file]}
-    response = connection.post url, body.to_json, headers
+    response = http_connection.post url, body.to_json
 
     case response.status
       when 200
@@ -60,8 +58,7 @@ class Runner::Strategy::Poseidon < Runner::Strategy
 
   def destroy_at_management
     Rails.logger.debug { "#{Time.zone.now.getutc.inspect}: Destroying runner at #{runner_url}" }
-    connection = Faraday.new nil, ssl: {ca_file: self.class.config[:ca_file]}
-    response = connection.delete runner_url, nil, self.class.headers
+    response = self.class.http_connection.delete runner_url
     self.class.handle_error response unless response.status == 204
   rescue Faraday::Error => e
     raise Runner::Error::FaradayError.new("Request to Poseidon failed: #{e.inspect}")
@@ -83,8 +80,7 @@ class Runner::Strategy::Poseidon < Runner::Strategy
     # First, clean the workspace and second, copy all files to their location.
     # This ensures that no artefacts from a previous submission remain in the workspace.
     body = {copy: copy, delete: ['./']}
-    connection = Faraday.new nil, ssl: {ca_file: self.class.config[:ca_file]}
-    response = connection.patch url, body.to_json, self.class.headers
+    response = self.class.http_connection.patch url, body.to_json
     return if response.status == 204
 
     Runner.destroy(@allocation_id) if response.status == 400
@@ -154,6 +150,12 @@ class Runner::Strategy::Poseidon < Runner::Strategy
     @headers ||= {'Content-Type' => 'application/json', 'Poseidon-Token' => config[:token]}
   end
 
+  def self.http_connection
+    @http_connection ||= Faraday.new(ssl: {ca_file: config[:ca_file]}, headers: headers) do |faraday|
+      faraday.adapter :net_http_persistent
+    end
+  end
+
   def self.parse(response)
     JSON.parse(response.body).deep_symbolize_keys
   rescue JSON::ParserError => e
@@ -167,8 +169,7 @@ class Runner::Strategy::Poseidon < Runner::Strategy
     url = "#{runner_url}/execute"
     body = {command: command, timeLimit: @execution_environment.permitted_execution_time}
     Rails.logger.debug { "#{Time.zone.now.getutc.inspect}: Preparing command execution at #{url}: #{command}" }
-    connection = Faraday.new nil, ssl: {ca_file: self.class.config[:ca_file]}
-    response = connection.post url, body.to_json, self.class.headers
+    response = self.class.http_connection.post url, body.to_json
 
     case response.status
       when 200

spec/lib/runner/strategy/poseidon_spec.rb

@@ -109,7 +109,7 @@ describe Runner::Strategy::Poseidon do
 
       it 'raises an error' do
         faraday_connection = instance_double 'Faraday::Connection'
-        allow(Faraday).to receive(:new).and_return(faraday_connection)
+        allow(described_class).to receive(:http_connection).and_return(faraday_connection)
         %i[post patch delete].each {|message| allow(faraday_connection).to receive(message).and_raise(Faraday::TimeoutError) }
         expect { action.call }.to raise_error(Runner::Error::FaradayError)
       end
@@ -122,20 +122,19 @@ describe Runner::Strategy::Poseidon do
 
     it 'makes the correct request to Poseidon' do
       faraday_connection = instance_double 'Faraday::Connection'
-      allow(Faraday).to receive(:new).and_return(faraday_connection)
+      allow(described_class).to receive(:http_connection).and_return(faraday_connection)
       allow(faraday_connection).to receive(:put).and_return(Faraday::Response.new(status: 201))
       action.call
-      expect(faraday_connection).to have_received(:put) do |url, body, headers|
+      expect(faraday_connection).to have_received(:put) do |url, body|
         expect(url).to match(%r{execution-environments/#{execution_environment.id}\z})
         expect(body).to eq(execution_environment.to_json)
-        expect(headers).to include({'Content-Type' => 'application/json'})
       end
     end
 
     shared_examples 'returns true when the api request was successful' do |status|
       it "returns true on status #{status}" do
         faraday_connection = instance_double 'Faraday::Connection'
-        allow(Faraday).to receive(:new).and_return(faraday_connection)
+        allow(described_class).to receive(:http_connection).and_return(faraday_connection)
         allow(faraday_connection).to receive(:put).and_return(Faraday::Response.new(status: status))
         expect(action.call).to be_truthy
       end
@@ -144,7 +143,7 @@ describe Runner::Strategy::Poseidon do
     shared_examples 'returns false when the api request failed' do |status|
       it "returns false on status #{status}" do
         faraday_connection = instance_double 'Faraday::Connection'
-        allow(Faraday).to receive(:new).and_return(faraday_connection)
+        allow(described_class).to receive(:http_connection).and_return(faraday_connection)
         allow(faraday_connection).to receive(:put).and_return(Faraday::Response.new(status: status))
         expect(action.call).to be_falsey
       end
@@ -160,7 +159,7 @@ describe Runner::Strategy::Poseidon do
 
     it 'returns false if Faraday raises an error' do
       faraday_connection = instance_double 'Faraday::Connection'
-      allow(Faraday).to receive(:new).and_return(faraday_connection)
+      allow(described_class).to receive(:http_connection).and_return(faraday_connection)
       allow(faraday_connection).to receive(:put).and_raise(Faraday::TimeoutError)
       expect(action.call).to be_falsey
     end