add common IPC tags to MDC (#984)

When logging to some systems the MDC values are used for
tagging. Having the common IPC tags available as part of
the MDC can make it easier to query them independently
where the JSON for the message is just treated as a string.

spectator-ext-ipc/src/main/java/com/netflix/spectator/ipc/IpcLogEntry.java

@@ -21,6 +21,7 @@
 import com.netflix.spectator.api.Tag;
 import com.netflix.spectator.api.histogram.PercentileTimer;
 import com.netflix.spectator.ipc.http.PathSanitizer;
+import org.slf4j.MDC;
 import org.slf4j.Marker;
 import org.slf4j.event.Level;
 
@@ -825,6 +826,57 @@ private String getExceptionMessage() {
         : exception.getMessage();
   }
 
+  private void putInMDC(String key, String value) {
+    if (value != null && !value.isEmpty()) {
+      MDC.put(key, value);
+    }
+  }
+
+  private void putInMDC(Tag tag) {
+    if (tag != null) {
+      putInMDC(tag.key(), tag.value());
+    }
+  }
+
+  void populateMDC() {
+    putInMDC("marker", marker.getName());
+
+    putInMDC("uri", uri);
+    putInMDC("path", path);
+    putInMDC(IpcTagKey.endpoint.key(), endpoint);
+
+    putInMDC(IpcTagKey.owner.key(), owner);
+    putInMDC(IpcTagKey.protocol.key(), protocol);
+    putInMDC(IpcTagKey.vip.key(), vip);
+
+    putInMDC("ipc.client.region", clientRegion);
+    putInMDC("ipc.client.zone", clientZone);
+    putInMDC("ipc.client.node", clientNode);
+    putInMDC(IpcTagKey.clientApp.key(), clientApp);
+    putInMDC(IpcTagKey.clientCluster.key(), clientCluster);
+    putInMDC(IpcTagKey.clientAsg.key(), clientAsg);
+
+    putInMDC("ipc.server.region", serverRegion);
+    putInMDC("ipc.server.zone", serverZone);
+    putInMDC("ipc.server.node", serverNode);
+    putInMDC(IpcTagKey.serverApp.key(), serverApp);
+    putInMDC(IpcTagKey.serverCluster.key(), serverCluster);
+    putInMDC(IpcTagKey.serverAsg.key(), serverAsg);
+
+    putInMDC("ipc.remote.address", remoteAddress);
+    putInMDC("ipc.remote.port", Integer.toString(remotePort));
+
+    putInMDC(attempt);
+    putInMDC(attemptFinal);
+
+    putInMDC(result);
+    putInMDC(status);
+    putInMDC(IpcTagKey.statusDetail.key(), statusDetail);
+
+    putInMDC(IpcTagKey.httpMethod.key(), httpMethod);
+    putInMDC(IpcTagKey.httpStatus.key(), Integer.toString(httpStatus));
+  }
+
   @Override
   public String toString() {
     return new JsonStringBuilder(builder)

spectator-ext-ipc/src/main/java/com/netflix/spectator/ipc/IpcLogger.java

@@ -22,6 +22,7 @@
 import com.netflix.spectator.api.patterns.CardinalityLimiters;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.slf4j.MDC;
 import org.slf4j.Marker;
 import org.slf4j.MarkerFactory;
 import org.slf4j.event.Level;
@@ -151,7 +152,9 @@ void log(IpcLogEntry entry) {
     }
 
     if (enabled.test(entry.getMarker())) {
+      entry.populateMDC();
       log.accept(entry.getMarker(), entry.toString());
+      MDC.clear();
     }
 
     // For successful responses we can reuse the entry to avoid additional allocations. Failed