add loki realtime logging

pilot/util/realtimelogger.py

@@ -179,7 +179,39 @@ def __init__(self, args, info_dic, workdir, secrets, level=INFO):
                     transport=transport,
                     database_path='logstash_test.db'
                 )
-
+            elif logtype == 'loki':
+                from loki_logger_handler.loki_logger_handler import LokiLoggerHandler
+
+                loki_labels = {'application': 'PanDA_Pilot', 'envirnment': 'Production'}
+                try:
+                    labels = os.environ.get('LOKI_LABELS', {})
+                    if labels:
+                        labels = json.loads(labels)
+                        loki_labels = labels
+                except Exception as ex:
+                    logger.warning(f'failed to load LOKI_LABELS from environment: {ex}')
+
+                loki_labelkeys = ['application', 'environment']
+                try:
+                    labelkeys = os.environ.get('LOKI_LABELKEYS', {})
+                    if labelkeys:
+                        labelkeys = json.loads(labelkeys)
+                        loki_labelkeys = labelkeys
+                except Exception as ex:
+                    logger.warning(f'failed to load LOKI_LABELKEYS from environment: {ex}')
+
+                try:
+                    loki_period = int(os.environ.get('LOKI_PERIOD', 30))
+                except Exception as ex:
+                    logger.warning(f'failed to load LOKI_PERIOD from environment: {ex}')
+                    loki_period = 30
+
+                _handler = LokiLoggerHandler(
+                    url=os.environ["LOKI_URL"],
+                    labels=loki_labels,
+                    labelKeys=loki_labelkeys,
+                    timeout=loki_period
+                )
             else:
                 logger.warning(f'unknown logtype: {logtype}')
                 _handler = None