Catch case where field is defined multiple times and add test

frigate/config.py

@@ -22,6 +22,7 @@ from frigate.util import (
     create_mask,
     deep_merge,
     escape_special_characters,
+    load_config_with_no_duplicates,
     load_labels,
 )
 
@@ -1011,7 +1012,7 @@ class FrigateConfig(FrigateBaseModel):
             raw_config = f.read()
 
         if config_file.endswith(YAML_EXT):
-            config = yaml.safe_load(raw_config)
+            config = load_config_with_no_duplicates(raw_config)
         elif config_file.endswith(".json"):
             config = json.loads(raw_config)
 

frigate/test/test_config.py

@@ -1,11 +1,13 @@
 import unittest
 import numpy as np
 from pydantic import ValidationError
+
 from frigate.config import (
     BirdseyeModeEnum,
     FrigateConfig,
     DetectorTypeEnum,
 )
+from frigate.util import load_config_with_no_duplicates
 
 
 class TestConfig(unittest.TestCase):
@@ -1452,6 +1454,23 @@ class TestConfig(unittest.TestCase):
 
         self.assertRaises(ValueError, lambda: frigate_config.runtime_config.cameras)
 
+    def test_fails_duplicate_keys(self):
+        raw_config = """
+        cameras:
+          test:
+            ffmpeg:
+              inputs:
+                - one
+                - two
+              inputs:
+                - three
+                - four
+        """
+
+        self.assertRaises(
+            ValueError, lambda: load_config_with_no_duplicates(raw_config)
+        )
+
     def test_object_filter_ratios_work(self):
         config = {
             "mqtt": {"host": "mqtt"},

frigate/util.py

@@ -5,7 +5,10 @@ import re
 import signal
 import traceback
 import urllib.parse
+import yaml
+
 from abc import ABC, abstractmethod
+from collections import Counter
 from collections.abc import Mapping
 from multiprocessing import shared_memory
 from typing import AnyStr
@@ -44,6 +47,33 @@ def deep_merge(dct1: dict, dct2: dict, override=False, merge_lists=False) -> dic
     return merged
 
 
+def load_config_with_no_duplicates(raw_config) -> dict:
+    """Get config ensuring duplicate keys are not allowed."""
+
+    # https://stackoverflow.com/a/71751051
+    class PreserveDuplicatesLoader(yaml.loader.Loader):
+        pass
+
+    def map_constructor(loader, node, deep=False):
+        keys = [loader.construct_object(node, deep=deep) for node, _ in node.value]
+        vals = [loader.construct_object(node, deep=deep) for _, node in node.value]
+        key_count = Counter(keys)
+        data = {}
+        for key, val in zip(keys, vals):
+            if key_count[key] > 1:
+                raise ValueError(
+                    f"Config input {key} is defined multiple times for the same field, this is not allowed."
+                )
+            else:
+                data[key] = val
+        return data
+
+    PreserveDuplicatesLoader.add_constructor(
+        yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG, map_constructor
+    )
+    return yaml.load(raw_config, PreserveDuplicatesLoader)
+
+
 def draw_timestamp(
     frame,
     timestamp,