Reading config file as dictionary in Flask

Question

in /instance/app.cfg I've configured :

test=test

In my flask file app.py :

with app.open_instance_resource('app.cfg') as f:
    config = f.read()
    print('config' , type(config))

Which prints config <class 'bytes'>

Reading the flask doc it does not detail how to read values from configuration files, how is this achieved ?

can config be read a dictionary instead of bytes ?

Update :

app.py :

# Shamelessly copied from http://flask.pocoo.org/docs/quickstart/

from flask import Flask
app = Flask(__name__)

import os

ac = app.config.from_pyfile(os.path.join('.', 'conf/api.conf'), silent=True)
logging_configuration = app.config.get('LOGGING')
if ac:
    print(logging.config.dictConfig(ac))

@app.route('/')
def hello_world():
    return 'Hello World!'

if __name__ == '__main__':
    app.run()

api.conf :

myvar=tester

returns error :

/./conf/api.conf", line 1, in <module>
    myvar=tester
NameError: name 'tester' is not defined

Update 2 :

app.py :

from flask import Flask
app = Flask(__name__)

import os
from logging.config import dictConfig

app.config.from_pyfile(os.path.join('.', 'conf/api.conf'), silent=True)

logging_configuration = app.config.get('LOGGING')
if logging_configuration:
    print(dictConfig(logging_configuration))

@app.route('/')
def hello_world():
    return 'Hello World!'

if __name__ == '__main__':
    app.run()

api.conf :

LOGGING="tester"

returns error :

ValueError: dictionary update sequence element #0 has length 1; 2 is required

Greg Eremeev · Accepted Answer · 2018-05-18T19:55:17.233

2

Reading the flask doc it does not detail how to read values from configuration files, how is this achieved ?

You can read about it in flask's doc here (title "configuring-from-files")

open_instance_resource is only a shortcut to make deal with files which are located in "instance folder" (a special place where you can store deploy specific files). It's not supposed to be a way to get your config as a dict.

Flask stores his config variable(app.config) as a dict object. You can update it via a bunch of methods: from_envvar, from_pyfile, from_object etc. Look at the source code

One of the typical ways how people read config files in flask-based apps:

app = Flask('your_app')
...
app.config.from_pyfile(os.path.join(basedir, 'conf/api.conf'), silent=True)
...

After that, you can use your dict-like config object as you want:

...
logging_configuration = app.config.get('LOGGING')
if logging_configuration:
    logging.config.dictConfig(logging_configuration)
...

from flask import Flask
app = Flask(__name__)

import os

app.config.from_pyfile(os.path.join('.', 'conf/api.conf'), silent=True)

@app.route('/')
def hello_world():
    return 'Hello World! {}'.format(app.config.get('LOGGING'))

if __name__ == '__main__':
    app.run()

edited May 18 '18 at 19:55

answered May 18 '18 at 16:47

Greg Eremeev

1,760
5
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please see question update. Is 'LOGGING' a property set in config file ? Using a custom property 'myvar' causes error. – blue-sky May 18 '18 at 18:53
@blue-sky you used from_pyfile. It means you have to provide a valid python file. Change your file content onto myvar="tester". In my example, variable LOGGING is just the valid variable, in terms of Python, which is located in Python module conf/api.conf. – Greg Eremeev May 18 '18 at 19:02
@blue-sky please, mark this answer as a right answer to show it other users – Greg Eremeev May 18 '18 at 19:22
please see further question update. I have not utilized 'LOGGING' correctly ? – blue-sky May 18 '18 at 19:37
@blue-sky You don't understand how to use Python correctly and SO. Don't update your question if this update changes the question completely. Try to read a doc about logging.config.dictConfig. You have to provide a dict! – Greg Eremeev May 18 '18 at 19:44
@blue-sky just delete the section with logging and it will work! You don't use logging in your example anyway. Return value from your config in 'hello_world' view if you wanna use it. – Greg Eremeev May 18 '18 at 19:49

score 0 · Answer 2 · answered May 18 '18 at 16:26

0

If you do app.config.from_pyfile('app.cfg') you can obtain your config as a dictionary by dict(app.config).

However, this dictionary will contain the whole configuration for your app not only those variables which were set by the configuration file.

answered May 18 '18 at 16:26

Jundiaius

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Reading config file as dictionary in Flask

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