AB#60301 add structured logging to commons

Author: avicarie

src/main/java/fi/hsl/common/logging/LogUtils.java

@@ -0,0 +1,21 @@
+package fi.hsl.common.logging;
+
+import org.slf4j.MDC;
+
+import java.util.Map;
+
+public class LogUtils {
+
+    private LogUtils() {
+
+    }
+
+    public static void withFields(Map<String, String> fields, Runnable loggingAction) {
+        fields.forEach(MDC::put);
+        try {
+            loggingAction.run();
+        } finally {
+            fields.keySet().forEach(MDC::remove);
+        }
+    }
+}

src/test/java/fi/hsl/common/logging/StructuredLoggingTest.java

@@ -0,0 +1,39 @@
+package fi.hsl.common.logging;
+
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.read.ListAppender;
+import org.junit.Test;
+import org.slf4j.LoggerFactory;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+public class StructuredLoggingTest {
+
+    private static final Logger log = (Logger) LoggerFactory.getLogger(StructuredLoggingTest.class);
+
+    @Test
+    public void testStructuredLoggingWithMDC() {
+        ListAppender<ILoggingEvent> listAppender = new ListAppender<>();
+        listAppender.start();
+        log.addAppender(listAppender);
+
+        Map<String, String> fields = Map.of("inFlight", "42", "userId", "KaladinStormblessed");
+        LogUtils.withFields(fields, () -> log.info("Processing messages"));
+
+        List<ILoggingEvent> logsList = listAppender.list;
+        assertEquals(1, logsList.size());
+
+        ILoggingEvent logEvent = logsList.get(0);
+
+        assertEquals("Processing messages", logEvent.getFormattedMessage());
+
+        assertEquals("42", logEvent.getMDCPropertyMap().get("inFlight"));
+        assertEquals("KaladinStormblessed", logEvent.getMDCPropertyMap().get("userId"));
+
+        listAppender.stop();
+    }
+}