Log error in a full string instead of json

In order to avoid complexity around parsing JSON, we log errors in one full string now

Co-authored-by: Neamah Al-Selwi <neamah.alselwi@digital.cabinet-office.gov.uk>
Co-authored-by: Tuomas Nylund <tuomas.nylund@digital.cabinet-office.gov.uk>

lib/govuk_app_config/govuk_json_logging.rb

@@ -13,15 +13,9 @@ def self.configure
       $stdout,
       level: Rails.logger.level,
       formatter: proc { |severity, datetime, _progname, msg|
-        begin
-          message = JSON.parse(msg)
-        rescue JSON::ParserError, TypeError => _e
-          message = msg
-        end
-
         hash = {
           "@timestamp": datetime.utc.iso8601(3),
-          message: message,
+          message: msg,
           level: severity,
           tags: %w[rails],
         }

lib/govuk_app_config/rails_ext/action_dispatch/debug_exceptions.rb

@@ -38,12 +38,9 @@ def log_error(request, wrapper)
 
             trace = wrapper.application_trace
             trace = wrapper.framework_trace if trace.empty?
+            exception.set_backtrace(trace)
 
-            logger.fatal({
-              exception_class: exception.class.to_s,
-              exception_message: exception.message,
-              stacktrace: trace,
-            }.to_json)
+            logger.fatal(exception.full_message)
           end
         end
       end

spec/lib/govuk_json_logging_spec.rb

@@ -22,6 +22,10 @@ def self.headers
 
   after { Rails.application = nil }
 
+  # By storing origin stdout in a constant and redirect `$stdout` to a fake one,
+  # We are able to inspect and test what is printed
+  # BUT it also suppress all the normal log outputs
+  # I.E. puts doesn't work anymore :D
   original_stderr = nil
   original_stdout = nil
 
@@ -97,12 +101,9 @@ def app
                                         ))
 
         error_log_json_msg = error_log_json["message"]
-        expect(error_log_json_msg).to match(hash_including(
-                                              "exception_class" => "StandardError",
-                                              "exception_message" => "default exception",
-                                            ))
-        expect(error_log_json_msg).to have_key("stacktrace")
-        expect(error_log_json_msg["stacktrace"]).to be_a(Array)
+        expect(error_log_json_msg).to include("StandardError")
+        expect(error_log_json_msg).to include("default exception")
+        expect(error_log_json_msg).to match(/from.*:[0-9]+:in.*/)
       end
 
       it "logs errors thrown by the application with no govuk_request_id" do
@@ -115,12 +116,9 @@ def app
         expect(error_log_line).not_to be_empty
         error_log_json = JSON.parse(error_log_line)
         error_log_json_msg = error_log_json["message"]
-        expect(error_log_json_msg).to match(hash_including(
-                                              "exception_class" => "StandardError",
-                                              "exception_message" => "default exception",
-                                            ))
-        expect(error_log_json_msg).to have_key("stacktrace")
-        expect(error_log_json_msg["stacktrace"]).to be_a(Array)
+        expect(error_log_json_msg).to include("StandardError")
+        expect(error_log_json_msg).to include("default exception")
+        expect(error_log_json_msg).to match(/from.*:[0-9]+:in.*/)
       end
 
       it "logs to stdout in JSON format with govuk_request_id" do