Bug

Please complete:

• OS: Linux
• Python version import sys; print(sys.version): 3.6.9
• Pydantic version import pydantic; print(pydantic.VERSION): 1.2

There is an example in docs about case sensitivity of environment variable names: https://pydantic-docs.helpmanual.io/usage/settings/#environment-variable-names.

I cite it here for convenience:

Case-sensitivity can be turned on through the Config:

from pydantic import BaseSettings

class Settings(BaseSettings):
    redis_host = 'localhost'

    class Config:
        case_sensitive = True

When case_sensitive is True, the environment variable must be in all-caps, so in this example redis_host could only be modified via export REDIS_HOST.

This example is simply incorrect. It leads that you can name Settings attrs using "snake_case", and export env variable named "UPPER_CASE", and Settings will catch them and populate proper attr with value taken from this env variable. This is not the case. In fact, if you want case sensitive environment variable names, you must name Settings attributes all "UPPER_CASE" as well.

Proof

Let's take this example "as is" and try to override settings attribute using environment variable:

import os
from pydantic import BaseSettings

class Settings(BaseSettings):
    redis_host = 'localhost'

    class Config:
        case_sensitive = True

Settings().redis_host
'localhost'  # default

os.environ['REDIS_HOST'] = 'myredis'  # according to example, we must name env var all UPPER_CASE
Settings().redis_host
'localhost'  # still default
os.environ['redis_host'] = 'myredis'
Settings().redis_host
'myredis'  # now it's working