feat: add support for case insensitive env names (#313)

* feat: add support for case insensitive env names

Closes #277

* feedback: just alias os.environ

* doc: update history

* doc: mention case_insensitive option

* refactor: feedback if-else expression assignment

* fix: formatting

* chore: encode black configuration in file to support IDEs

* docs: fix example

* feedback: no suppport for IDEs in this PR

* feedback: style

HISTORY.rst

@@ -8,6 +8,7 @@ v0.16.0 (2018-XX-XX)
 
 * refactor schema generation to be compatible with JSON Schema and OpenAPI specs, #308 by @tiangolo
 * add ``schema`` to ``schema`` module to generate top-level schemas from base models, #308 by @tiangolo
+* add ``case_insensitive`` option to ``BaseSettings`` ``Config``, #277 by @jasonkuhrt
 
 v0.15.0 (2018-11-18)
 ....................

docs/examples/settings_case_insensitive.py

@@ -0,0 +1,8 @@
+from pydantic import BaseSettings
+
+
+class Settings(BaseSettings):
+    redis_host = 'localhost'
+
+    class Config:
+        case_insensitive = True

docs/index.rst

@@ -231,7 +231,7 @@ Outputs:
 
 The generated schemas are compliant with the specifications:
 `JSON Schema Core <https://json-schema.org/latest/json-schema-core.html>`__,
-`JSON Schema Validation <https://json-schema.org/latest/json-schema-validation.html>`__ and 
+`JSON Schema Validation <https://json-schema.org/latest/json-schema-validation.html>`__ and
 `OpenAPI <https://github.com/OAI/OpenAPI-Specification>`__.
 
 ``BaseModel.schema`` will return a dict of the schema, while ``BaseModel.schema_json`` will return a JSON string
@@ -459,6 +459,12 @@ Here ``redis_port`` could be modified via ``export MY_PREFIX_REDIS_PORT=6380`` o
 
 Complex types like ``list``, ``set``, ``dict`` and submodels can be set by using JSON environment variables.
 
+Environment variables can be read in a case insensitive manner:
+
+.. literalinclude:: examples/settings_case_insensitive.py
+
+Here ``redis_port`` could be modified via ``export APP_REDIS_HOST``, ``export app_redis_host``, ``export app_REDIS_host``, etc.
+
 Dynamic model creation
 ......................
 

pydantic/env_settings.py

@@ -21,7 +21,9 @@ class BaseSettings(BaseModel):
     """
     Base class for settings, allowing values to be overridden by environment variables.
 
-    Environment variables must be upper case. Eg. to override foobar, `export APP_FOOBAR="whatever"`.
+    Environment variables must be upper case and prefixed by APP_ by default. Eg. to override foobar,
+    `export APP_FOOBAR="whatever"`. To change this behaviour set Config options case_insensitive and
+    env_prefix.
 
     This is useful in production for secrets you do not wish to save in code, it places nicely with docker(-compose),
     Heroku and any 12 factor app design.
@@ -36,23 +38,34 @@ class BaseSettings(BaseModel):
         Substitute environment variables into values.
         """
         d = {}
+
+        if self.__config__.case_insensitive:
+            env_vars = {k.lower(): v for (k, v) in os.environ.items()}
+        else:
+            env_vars = os.environ
+
         for field in self.__fields__.values():
+
             if field.has_alias:
                 env_name = field.alias
             else:
                 env_name = self.__config__.env_prefix + field.name.upper()
-            env_var = os.getenv(env_name, None)
-            if env_var:
+
+            env_name_ = env_name.lower() if self.__config__.case_insensitive else env_name
+            env_val = env_vars.get(env_name_, None)
+
+            if env_val:
                 if _complex_field(field):
                     try:
-                        env_var = json.loads(env_var)
+                        env_val = json.loads(env_val)
                     except ValueError as e:
                         raise SettingsError(f'error parsing JSON for "{env_name}"') from e
-                d[field.alias] = env_var
+                d[field.alias] = env_val
         return d
 
     class Config:
-        env_prefix = 'APP_'
+        env_prefix = "APP_"
         validate_all = True
         ignore_extra = False
         arbitrary_types_allowed = True
+        case_insensitive = False

tests/test_settings.py

@@ -110,3 +110,18 @@ def test_alias_matches_name(env):
     env.set('foobar', 'xxx')
     s = Settings()
     assert s.foobar == 'xxx'
+
+
+def test_case_insensitive(env):
+    class Settings(BaseSettings):
+        foo: str
+        bAR: str
+
+        class Config:
+            case_insensitive = True
+
+    env.set('apP_foO', 'foo')
+    env.set('app_bar', 'bar')
+    s = Settings()
+    assert s.foo == 'foo'
+    assert s.bAR == 'bar'