Two imports were missing

src/telemetry/frontend/service/__main__.py

+# Copyright 2022-2023 ETSI TeraFlowSDN - TFS OSG (https://tfs.etsi.org/)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import signal
+import sys
+import logging, threading
+from .TelemetryFrontendService import TelemetryFrontendService
+from monitoring.service.NameMapping import NameMapping
+from monitoring.service.EventTools import EventsDeviceCollector
+from common.Settings import (
+    get_log_level, wait_for_environment_variables, get_env_var_name, 
+    get_metrics_port )
+
+terminate = threading.Event()
+LOGGER = None
+
+def signal_handler(signal, frame): # pylint: disable=redefined-outer-name
+    LOGGER.warning('Terminate signal received')
+    terminate.set()
+
+def main():
+    global LOGGER
+
+    log_level = get_log_level()
+    logging.basicConfig(level=log_level, format="[%(asctime)s] %(levelname)s:%(name)s:%(message)s")
+    LOGGER = logging.getLogger(__name__)
+
+# ------- will be added later --------------
+    # wait_for_environment_variables([
+    #     get_env_var_name
+
+
+    # ])
+# ------- will be added later --------------
+
+    signal.signal(signal.SIGINT,  signal_handler)
+    signal.signal(signal.SIGTERM, signal_handler)
+
+    LOGGER.info('Starting...')
+
+    # Start metrics server
+    metrics_port = get_metrics_port()
+    start_http_server(metrics_port)
+
+    name_mapping = NameMapping()
+
+    grpc_service = TelemetryFrontendService(name_mapping)
+    grpc_service.start()
+
+    # Wait for Ctrl+C or termination signal
+    while not terminate.wait(timeout=1.0): pass
+
+    LOGGER.info('Terminating...')
+    grpc_service.stop()
+
+    LOGGER.info('Bye')
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main())
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