add parser for environment variables WIP

config.yaml

@@ -18,6 +18,7 @@ filters:
   image_to_page_quotient: # Image size to page size ratio (ratio of geometric means of areas)
     min: $MIN_REL_IMAGE_SIZE|0.05  # Minimum permissible
     max: $MAX_REL_IMAGE_SIZE|0.75  # Maximum permissible
+    # Fixme: Temporary solution, delete
     customized: # Customized settings per class (RED-5202)
       max:
         signature: $MAX_REL_SIGNATURE_SIZE|0.4

image_prediction/exceptions.py

@@ -32,3 +32,7 @@ class IntentionalTestException(RuntimeError):
 
 class InvalidBox(Exception):
     pass
+
+
+class ParsingError(Exception):
+    pass

image_prediction/transformer/transformers/response.py

@@ -1,9 +1,14 @@
+import json
 import math
+import os
+from functools import lru_cache
 from operator import itemgetter
 
 from image_prediction.config import CONFIG
+from image_prediction.exceptions import ParsingError
 from image_prediction.transformer.transformer import Transformer
 from image_prediction.utils import get_logger
+from funcy import filter, juxt, first, rest
 
 logger = get_logger()
 
@@ -83,3 +88,26 @@ def __is_max_image_to_page_quotient_breached(quotient: float, label: str) -> boo
     max_quotient = customized_entries.get(label, default_max_quotient)
     max_quotient = max_quotient if max_quotient else default_max_quotient
     return bool(quotient > max_quotient)
+
+
+@lru_cache(maxsize=None)
+def parse_env_var(prefix, fallback_value):
+    head, tail = juxt(first, rest)(filter(prefix, os.environ))
+    if not head or tail:
+        logger.warning(
+            f"Found multiple candidates for environment variable with prefix '{prefix}', falling back to default value."
+        )
+        return fallback_value
+    else:
+        try:
+            return parse_env_var_value(os.environ[head])
+        except ParsingError as err:
+            logger.warning(f"{err}, falling back to default value.")
+            return fallback_value
+
+
+def parse_env_var_value(env_var_value):
+    try:
+        return json.loads(env_var_value)
+    except Exception as err:
+        raise ParsingError(f"Failed to parse {env_var_value}") from err

test/unit_tests/config_test.py

@@ -3,7 +3,7 @@ import tempfile
 import pytest
 import yaml
 
-from image_prediction.config import Config, DotIndexable
+from image_prediction.config import Config
 
 
 @pytest.fixture
@@ -40,7 +40,7 @@ def test_access_key_does_not_exists(config):
 
 def test_get_method_returns_key_if_key_does_exist(config):
     dot_indexable = config.D.E
-    assert dot_indexable.get("F", "default_value") == True
+    assert dot_indexable.get("F", "default_value") is True
 
 
 def test_get_method_returns_default_if_key_does_not_exist(config):