You need to add an environment variable file in root directory named .env.In general,it should contain following items.
#!/bin/sh
SECRET_KEY = 'difficult to guess secrect'
BLOG_ADMIN = 'example@email.com'
BLOG_MAIL_SENDER = 'BLOG manager example@email.com'
MAIL_USERNAME = 'example@email.com'
MAIL_PASSWORD = 'yourpassword'
DEV_SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://username:password@IP:port/dev_blog?charset=utf8'
TEST_SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://username:password@IP:port/test_blog?charset=utf8'
SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://username:password@IP:port/blog?charset=utf8'