Add JSON logging support via LOGGING_JSON config option

doc/config/environment-variables.md

@@ -43,6 +43,7 @@ This document contains all the environment variables which are available for thi
 | `LOGGING_SENTRY_DSN` | String | A DSN which should be used to report exceptions to Sentry |  |
 | `LOGGING_ENABLED` | Boolean | Enable the Postal logger to log to STDOUT | true |
 | `LOGGING_HIGHLIGHTING_ENABLED` | Boolean | Enable highlighting of log lines | false |
+| `LOGGING_JSON` | Boolean | Enable JSON formatting for log output | false |
 | `GELF_HOST` | String | GELF-capable host to send logs to |  |
 | `GELF_PORT` | Integer | GELF port to send logs to | 12201 |
 | `GELF_FACILITY` | String | The facility name to add to all log entries sent to GELF | postal |

doc/config/yaml.yml

@@ -89,6 +89,8 @@ logging:
   enabled: true
   # Enable highlighting of log lines
   highlighting_enabled: false
+  # Enable JSON formatting for log output
+  json: false
 
 gelf:
   # GELF-capable host to send logs to

lib/postal/config.rb

@@ -81,7 +81,8 @@ def host_with_protocol
 
     def logger
       @logger ||= begin
-        k = Klogger.new(nil, destination: Config.logging.enabled? ? $stdout : "/dev/null", highlight: Config.logging.highlighting_enabled?)
+        formatter = Config.logging.json? ? :json : :go
+        k = Klogger.new(nil, destination: Config.logging.enabled? ? $stdout : "/dev/null", formatter: formatter, highlight: Config.logging.highlighting_enabled?)
         k.add_destination(graylog_logging_destination) if Config.gelf.host.present?
         k
       end

lib/postal/config_schema.rb

@@ -223,6 +223,11 @@ module Postal
         description "Enable highlighting of log lines"
         default false
       end
+
+      boolean :json do
+        description "Enable JSON formatting for log output"
+        default false
+      end
     end
 
     group :gelf do

spec/lib/postal_spec.rb

@@ -15,4 +15,26 @@
       expect { Postal.change_database_connection_pool_size(8) }.to change { ActiveRecord::Base.connection_pool.size }.from(5).to(8)
     end
   end
+
+  describe "#logger" do
+    before do
+      Postal.instance_variable_set(:@logger, nil)
+    end
+
+    after do
+      Postal.instance_variable_set(:@logger, nil)
+    end
+
+    it "uses the go formatter by default" do
+      allow(Postal::Config.logging).to receive(:json?).and_return(false)
+      logger = Postal.logger
+      expect(logger.formatter).to be_a(Klogger::Formatters::Go)
+    end
+
+    it "uses the json formatter when json logging is enabled" do
+      allow(Postal::Config.logging).to receive(:json?).and_return(true)
+      logger = Postal.logger
+      expect(logger.formatter).to be_a(Klogger::Formatters::JSON)
+    end
+  end
 end