Working with Python-Flask-MySQL

If you want to develop a webservice using python, flask and MySQL, here are some setup instructions and pre-requisites which are required, for both platforms — Windows and Linux.

(Also, I have added some tips and tricks for some of the issues I had faced)

Step -1

Check the Python version using,

$ python -V

Download the latest python version 3.X

$ sudo apt-get install python3-pi

Step-2

You need to install the below dependencies using,

$ pip install -r pymysql
$ pip install -r Flask
$ pip install -r Flask-cors
$ pip install -r simpleJson

(Also, you need to install some extra dependencies you are using)

Step-3

Create a config file, config.py and add your connection details

DB_CONF = {
'host':'<YOUR-MYSQL-HOST>',
'port':3306,
'user':'<YOUR-MYSQL-USERNAME>',
'passwd':'<YOUR-MYSQL-PASSWORD>',
'db':'<YOUR-MYSQL-DATABASE>'
}
In main.py, put your real query like this,
sql="<PUT YOUR MySQL QUERY HERE>"
eg.
@app.route(‘/testWebService’)
def test_get():
# create mysql connection
Conn = pymysql.connect(host=config.DB_CONF[‘host’],
port=config.DB_CONF[‘port’],
user=config.DB_CONF[‘user’],
passwd=config.DB_CONF[‘passwd’],
db=config.DB_CONF[‘db’])
cur = conn.cursor()
sql="<PUT YOUR MySQL QUERY HERE>"
cur.execute(sql)

Step-4

Start a web service,

On Windows, you can start the web service using,

>waitress-serve — listen=*:8080 main:app

On Ubuntu, you can use,

$ gunicorn — log-level debug — bind 0.0.0.0:30443 server:app

For Python3,
$ gunicorn3 --log-level debug --bind 0.0.0.0:30443 server:app

In Ubuntu, you may face timeout issue. In that case, you can execute the command,

$ gunicorn3 --workers=3 --bind 0.0.0.0:3000 main:app

If the command fails, saying there are already some instance running (zombie processes) and you want to restart the service, you can execute this command before above command,

$ sudo fuser -k 3000/tcp

(You may want to add all these commands, and get the logs in shell file, execute below command)

$ ./sampleWebService.sh

Thank You!