Connect multiple cloud sql databases to one app engine service

[Mike Hardy]

Hi, we have an app that utilizes two databases. Previously, we had the two databases on the same instance in Cloud SQL, but we want to split the databases into separate instances. We're having issues connecting the databases to our Django app engine service. Is this even possible? If so, how would the app.yaml look?

old app.yaml

runtime: custom

env: flex

entrypoint: gunicorn --timeout 360 --graceful-timeout 360 -b :$8080 localinsights.wsgi

beta_settings:

    cloud_sql_instances: <CONNECTION>

runtime_config:

  python_version: 3.6

env_variables:

  SQLALCHEMY_DATABASE_URI: >-

      postgresql+psycopg2://<USER>:<PASSWORD>/<DB>?host=/cloudsql/<CONNECTION>

settings.py

DATABASES['default'] = {

    'HOST': '/cloudsql/<CONNECTION>',

    'ENGINE': 'psqlextra.backend',

    'NAME': '<USER_DB>',

    'USER': '<USER>',

    'PASSWORD': '<PASSWORD>'

}

DATABASES['NUMBER_2'] = {

    'HOST': '/cloudsql/<CONNECTION>',

    'ENGINE': 'psqlextra.backend',

    'NAME': 'NUMBER_2',

    'USER': '<USER>',

    'PASSWORD': '<PW>'

}

[Jun (Cloud Platform Support)]

Hi Mike,

You should be able to connect to multiple Cloud SQL instances through Cloud SQL Proxy, and you can specify multiple instances in the instances parameter (comma separated). Please take a look at these two posts for more details: "A GCE instance connecting to two (or more) Cloud SQL databases via multiple cloud-sql-proxy-instances" and "Connecting to multiple CloudSQL instances using Cloud sql proxy?", which have the similar questions. 

- Jun

[Mike Hardy]

Hi Jun, thanks for your response, but I am a little confused here. When deployed, GAE uses a built in cloud sql proxy connection with Cloud SQL so there is no way to specify the instance or any other parameter for cloud sql proxy. I think any fix will need to use app.yaml but please correct me if I'm wrong. Would love to solve this.

[Jun (Cloud Platform Support)]

Hi Mike,

After some further search around, it looks there is no public documentation mentioning GAE connects to multiple Cloud SQL instances. From my point of view, config at app.yaml will not get to the purpose we want, so I suggest that you'll need to make a feature request at the issue tracker.