SPRINT-15: attempt to improve json logging

qqq-backend-core/src/main/resources/log4j2.xml

@@ -7,7 +7,7 @@
       </Console>
       <Syslog name="SyslogAppender" format="RFC5424" host="localhost" port="514" protocol="UDP" appName="qqq" facility="LOCAL0">
          <LevelRangeFilter minLevel="ERROR" maxLevel="INFO" onMatch="ACCEPT" onMismatch="DENY"/>
-         <PatternLayout pattern="java %date{ISO8601} | %relative | %level | %threadName | %logger{1} | %message%n"/>
+         <JsonTemplateLayout eventTemplateUri="classpath:logTemplate.json"/>
       </Syslog>
       <File name="LogFileAppender" fileName="log/qqq.log">
          <LevelRangeFilter minLevel="ERROR" maxLevel="all" onMatch="ACCEPT" onMismatch="DENY"/>

qqq-backend-core/src/main/resources/logTemplate.json

@@ -0,0 +1,49 @@
+{
+   "@timestamp": {
+      "$resolver": "timestamp",
+      "pattern": {
+         "format": "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'",
+         "timeZone": "UTC"
+      }
+   },
+   "ecs.version": "1.2.0",
+   "log.level": {
+      "$resolver": "level",
+      "field": "name"
+   },
+   "message": {
+      "$resolver": "message",
+      "stringified": true
+   },
+   "process.thread.name": {
+      "$resolver": "thread",
+      "field": "name"
+   },
+   "log.logger": {
+      "$resolver": "logger",
+      "field": "name"
+   },
+   "labels": {
+      "$resolver": "mdc",
+      "flatten": true,
+      "stringified": true
+   },
+   "tags": {
+      "$resolver": "ndc"
+   },
+   "error.type": {
+      "$resolver": "exception",
+      "field": "className"
+   },
+   "error.message": {
+      "$resolver": "exception",
+      "field": "message"
+   },
+   "error.stack_trace": {
+      "$resolver": "exception",
+      "field": "stackTrace",
+      "stackTrace": {
+         "stringified": true
+      }
+   }
+}