add notice

src/bytewax/influxdb/__init__.py

@@ -1,6 +1,8 @@
 """Sink and source connectors for influxdb."""
 
 import logging
+import os
+import sys
 from datetime import datetime, timedelta, timezone
 from typing import Any, Dict, List, NamedTuple, Optional, Union
 
@@ -11,6 +13,17 @@
 from bytewax.inputs import FixedPartitionedSource, StatefulSourcePartition
 from bytewax.outputs import DynamicSink, StatelessSinkPartition
 
+if "BYTEWAX_LICENSE" not in os.environ:
+    msg = (
+        "`{{cookiecutter.project_slug}}` is commercially licensed "
+        "with publicly available source code.\n"
+        "You are welcome to prototype using this module for free, "
+        "but any use on business data requires a paid license.\n"
+        "See https://modules.bytewax.io/ for a license. "
+        "Set the env var `BYTEWAX_LICENSE=1` to suppress this message."
+    )
+    print(msg, file=sys.stderr)
+
 # Configure logging
 logging.basicConfig(level=logging.INFO)
 logger = logging.getLogger(__name__)