flask的配置设置的几种方式

　　 Flask的配置对象（config）是一个字典(dict)的子类（subclass），所以你可以把配置用键值对的方式存储进去。

1、一些重要的配置，可以设置在系统环境变量里，又或者放到某个服务器里，用的时候下载配置文件并读取配置

# 在linux系统里设置环境变量
export MAIL_USERNAME=me@greyli.com

# 用的时候取环境变量
import os
from flask import Flask

app = Flask(__name__)
app.config['MAIL_USERNAME'] = os.getenv('MAIL_USERNAME', 'me@greyli.com') # os.geteve(key,default=None)  Get an environment variable, return None if it 
# doesn't exist.The optional second argument can specify an alternate default.

2、直接写入主脚本

from flask import Flask

app = Flask(__name__)
app.config['SECRET_KEY'] = 'some secret words'
app.config['DEBUG'] = True
app.config['ITEMS_PER_PAGE'] = 10

或者写成下面的方式：

from flask import Flask

app = Flask(__name__)
app.config.update(
    DEBUG=True,
    SECRET_KEY='some secret words',
    ITEMS_PER_PAGE=10
)

3、单独的配置文件configure.py

SECRET_KEY = 'some secret words'
DEBUG = True
ITEMS_PER_PAGE = 10

在创建程序实例后导入配置

import config

...
app = Flask(__name__)
app.config.from_object(configure)
...

4、为开发环境、测试环境、生成环境、预发布环境创建不同的测试类

 import os
 basedir = os.path.abspath(os.path.dirname(__file__))

 class BaseConfig:  # 基本配置类
     SECRET_KEY = os.getenv('SECRET_KEY', 'some secret words')
     ITEMS_PER_PAGE = 10

 class DevelopmentConfig(BaseConfig):
     DEBUG = True
     SQLALCHEMY_DATABASE_URI = os.getenv('DEV_DATABASE_URL', 'sqlite:///' + os.path.join(basedir, 'data-dev.sqlite')

 class TestingConfig(BaseConfig):
     TESTING = True
     SQLALCHEMY_DATABASE_URI = os.getenv('TEST_DATABASE_URL', 'sqlite:///' + os.path.join(basedir, 'data-test.sqlite')
     WTF_CSRF_ENABLED = False

 config = {
     'development': DevelopmentConfig,
     'testing': TestingConfig,

     'default': DevelopmentConfig
 }

config.py

导入配置

from config import config  # 导入存储配置的字典

...
app = Flask(__name__)
app.config.from_object(config['development'])  # 获取相应的配置类
...

5、附下flask内置的配置列表

DEBUG	enable/disable debug mode
TESTING	enable/disable testing mode
PROPAGATE_EXCEPTIONS	explicitly enable or disable the propagation of exceptions. If not set or explicitly set to Nonethis is implicitly true if either TESTING orDEBUG is true.
PRESERVE_CONTEXT_ON_EXCEPTION	By default if the application is in debug mode the request context is not popped on exceptions to enable debuggers to introspect the data. This can be disabled by this key. You can also use this setting to force-enable it for non debug execution which might be useful to debug production applications (but also very risky).
SECRET_KEY	the secret key
SESSION_COOKIE_NAME	the name of the session cookie
SESSION_COOKIE_DOMAIN	the domain for the session cookie. If this is not set, the cookie will be valid for all subdomains of SERVER_NAME.
SESSION_COOKIE_PATH	the path for the session cookie. If this is not set the cookie will be valid for all of APPLICATION_ROOT or if that is not set for '/'.
SESSION_COOKIE_HTTPONLY	controls if the cookie should be set with the httponly flag. Defaults to True.
SESSION_COOKIE_SECURE	controls if the cookie should be set with the secure flag. Defaults to False.
PERMANENT_SESSION_LIFETIME	the lifetime of a permanent session asdatetime.timedelta object. Starting with Flask 0.8 this can also be an integer representing seconds.
SESSION_REFRESH_EACH_REQUEST	this flag controls how permanent sessions are refreshed. If set to True (which is the default) then the cookie is refreshed each request which automatically bumps the lifetime. If set to False a set-cookie header is only sent if the session is modified. Non permanent sessions are not affected by this.
USE_X_SENDFILE	enable/disable x-sendfile
LOGGER_NAME	the name of the logger
LOGGER_HANDLER_POLICY	the policy of the default logging handler. The default is 'always' which means that the default logging handler is always active. 'debug' will only activate logging in debug mode, 'production' will only log in production and 'never' disables it entirely.
SERVER_NAME	the name and port number of the server. Required for subdomain support (e.g.:'myapp.dev:5000') Note that localhost does not support subdomains so setting this to “localhost” does not help. Setting a SERVER_NAME also by default enables URL generation without a request context but with an application context.
APPLICATION_ROOT	If the application does not occupy a whole domain or subdomain this can be set to the path where the application is configured to live. This is for session cookie as path value. If domains are used, this should be None.
MAX_CONTENT_LENGTH	If set to a value in bytes, Flask will reject incoming requests with a content length greater than this by returning a 413 status code.
SEND_FILE_MAX_AGE_DEFAULT	Default cache control max age to use withsend_static_file() (the default static file handler) and send_file(), asdatetime.timedelta or as seconds. Override this value on a per-file basis using theget_send_file_max_age() hook on Flask orBlueprint, respectively. Defaults to 43200 (12 hours).
TRAP_HTTP_EXCEPTIONS	If this is set to True Flask will not execute the error handlers of HTTP exceptions but instead treat the exception like any other and bubble it through the exception stack. This is helpful for hairy debugging situations where you have to find out where an HTTP exception is coming from.
TRAP_BAD_REQUEST_ERRORS	Werkzeug’s internal data structures that deal with request specific data will raise special key errors that are also bad request exceptions. Likewise many operations can implicitly fail with a BadRequest exception for consistency. Since it’s nice for debugging to know why exactly it failed this flag can be used to debug those situations. If this config is set to Trueyou will get a regular traceback instead.
PREFERRED_URL_SCHEME	The URL scheme that should be used for URL generation if no URL scheme is available. This defaults to http.
JSON_AS_ASCII	By default Flask serialize object to ascii-encoded JSON. If this is set to False Flask will not encode to ASCII and output strings as-is and return unicode strings.  jsonify will automatically encode it in utf-8 then for transport for instance.
JSON_SORT_KEYS	By default Flask will serialize JSON objects in a way that the keys are ordered. This is done in order to ensure that independent of the hash seed of the dictionary the return value will be consistent to not trash external HTTP caches. You can override the default behavior by changing this variable. This is not recommended but might give you a performance improvement on the cost of cachability.
JSONIFY_PRETTYPRINT_REGULAR	If this is set to True (the default) jsonify responses will be pretty printed if they are not requested by an XMLHttpRequest object (controlled by the X-Requested-With header)
JSONIFY_MIMETYPE	MIME type used for jsonify responses.
TEMPLATES_AUTO_RELOAD	Whether to check for modifications of the template source and reload it automatically. By default the value is None which means that Flask checks original file only in debug mode.
EXPLAIN_TEMPLATE_LOADING	If this is enabled then every attempt to load a template will write an info message to the logger explaining the attempts to locate the template. This can be useful to figure out why templates cannot be found or wrong templates appear to be loaded.

参考：1、https://zhuanlan.zhihu.com/p/24055329?refer=flask

　　　2、http://flask.pocoo.org/docs/0.11/config/#configuration-handling

　　　3、http://www.cnblogs.com/m0m0/p/5624315.html