Google Cloud Function with Cloud MySQL Authorisation fails ([Errno 111] Connection refused)

Question

I'm trying to connect to my Google Cloud MySQL database through a Google Cloud Function to read some data. The function build succeeds, but when executed only this is displayed:

Error: (pymysql.err.OperationalError) (2003, "Can't connect to MySQL server on 'localhost' ([Errno 111] Connection refused)") (Background on this error at: http://sqlalche.me/e/e3q8)

Here is my connection code:

import sqlalchemy

# Depending on which database you are using, you'll set some variables differently. 
# In this code we are inserting only one field with one value. 
# Feel free to change the insert statement as needed for your own table's requirements.

# Uncomment and set the following variables depending on your specific instance and database:
connection_name = "single-router-309308:europe-west4:supermarkt-database"
db_name = "supermarkt-database"
db_user = "hidden"
db_password = "hidden"

# If your database is MySQL, uncomment the following two lines:
driver_name = 'mysql+pymysql'
query_string = dict({"unix_socket": "/cloudsql/{}".format(connection_name)})

# If the type of your table_field value is a string, surround it with double quotes. < SO note: I didn't really understand this line. Is this the problem?

def insert(request):
    request_json = request.get_json()
    stmt = sqlalchemy.text('INSERT INTO products VALUES ("Testid", "testname", "storename", "testbrand", "4.20", "1kg", "super lekker super mooi", "none")')
    
    db = sqlalchemy.create_engine(
      sqlalchemy.engine.url.URL(
        drivername=driver_name,
        username=db_user,
        password=db_password,
        database=db_name,
        query=query_string,
      ),
      pool_size=5,
      max_overflow=2,
      pool_timeout=30,
      pool_recycle=1800
    )
    try:
        with db.connect() as conn:
            conn.execute(stmt)
    except Exception as e:
        return 'Error: {}'.format(str(e))
    return 'ok'

I got it mostly from following this tutorial: https://codelabs.developers.google.com/codelabs/connecting-to-cloud-sql-with-cloud-functions#0 . I'm also using Python 3.7, as used in the tutorial. SQLAlchemy describes it as not necessarily under the control of the programmer. For context, the account through which is being connected has the SQL Cloud Admin role, and the Cloud SQL Admin API is enabled. Thanks in advance for the help!

PS: I did find this answer: Connecting to Cloud SQL from Google Cloud Function using Python and SQLAlchemy but have no idea where the settings for Firewall with SQL can be found. I didn't find them in SQL > Connection / Overview or Firewall.

Answer 1

Alright so I figured it out! In Edit Function > Runtime, Build and Connection Settings, head over to Connection Settings and make sure "Only route requests to private IPs through the VPC connector" is enabled. The VPC connector requires different authorization.

Also, apparently I needed my TABLE name, not my DATABASE name as the variable DB_NAME. Thanks @guillaume blaquiere for your assistance!