App engine instances can't connect to Google Cloud SQL instance

Mitul Amin

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Nov 18, 2015, 9:43:51 AM11/18/15

to Google App Engine

Hello,

Today, just before 12pm, my app on app engine started throwing com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure exceptions. It seems like it is not able to connect to my sql instance, but the sql instance is running. I can connect to it from my machine in the office as well as another externally hosted server.

I have two apps on app engine and this issue is affecting just one of them.

I have shutdown the one and only dynamic instance for the app and tried visiting the site which started a new instance and that still has the problem.

Has anybody else facing a similar situation at the moment or has faced this in the past? Any suggestions?

Thanks,

Mitul

Adam

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Nov 18, 2015, 6:49:53 PM11/18/15

to Google App Engine

This first thing I would check is to make sure your App Engine application's Project ID is still set under 'Authorized App Engine applications' [1]. It it is, try restarting the CloudSQL instance itself (click on the instance name, then 'Restart' at the top).

[1] https://cloud.google.com/sql/docs/access-control#appengine

Mitul Amin

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Nov 19, 2015, 6:21:00 AM11/19/15

to Google App Engine

Hi Adam,

This was a working app that stopped working all of a sudden. We raised a ticket with Google and have now sorted it out. It seems Google is bringing security constraints for Apps so that when using the Google Mysql Driver, you have to specify the db address as projectid:instanceid and not the IP address. This rule was enabled on our app at mid day yesterday that caused the app to not be able to connect to the DB. We have updated the app now and all seems to work as normal again.