Use an explicit encoding when reading the configuration file

[kkirsche]

Describe the bug

When the python option PYTHONWARNDEFAULTENCODING is set as described on https://docs.python.org/3/library/io.html#opt-in-encodingwarning

/Users/kkirsche/Library/Caches/pypoetry/virtualenvs/application-7pVymVLv-py3.11/lib/python3.11/site-packages/alembic/config.py:204: EncodingWarning: 'encoding' argument not specified
  file_config.read([self.config_file_name])

Expected behavior
Alembic will explicitly specify the encoding to use when reading the configuration file. Per https://docs.python.org/3/library/io.html#opt-in-encodingwarning, the recommendation would be to use "utf-8".

To Reproduce
Run an alembic migration with the environment variablePYTHONWARNDEFAULTENCODING set to any value. In my testing, I am using 1 as my value.

Error

/Users/kkirsche/Library/Caches/pypoetry/virtualenvs/application-7pVymVLv-py3.11/lib/python3.11/site-packages/alembic/config.py:204: EncodingWarning: 'encoding' argument not specified
  file_config.read([self.config_file_name])

Versions.

• OS: macOS 13.4.1 (c) (22F770820d)
• Python: Python 3.11.4
• Alembic: 1.11.1
• SQLAlchemy: 2.0.18[mysql, mypy]
• Database: mariadb from 11.0.2-MariaDB, client 15.2 for osx10.18 (arm64) using EditLine wrapper
• DBAPI: mysqlclient 2.2.0

Additional context
The read function passes the encoding to https://docs.python.org/3/library/io.html#io.text_encoding

For me, this returns "locale" which may make sense to use if you are not comfortable with "utf-8". "locale" which, as I understand it, uses https://docs.python.org/3/library/locale.html to detect the encoding settings of the caller's machine.

Thank you for your consideration

Have a nice day!

[zzzeek]

that's fine, can you please send a pull request? thanks

[kkirsche]

Course, sent 🙂

Thank you for your time and consideration.

[sqla-tester]

Kevin Kirsche has proposed a fix for this issue in the main branch:

Specify "locale" encoding when reading configuration file https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/4786