Dimitris's questions

I have a fairly standard setup where the application server is separated by a firewall from the database server. The application is using sqlalchemy and the db is postgres.

The system works fine for a few hours, but once it remains idle for a long period it appears that the communication fails between the server and the db. The error log is:

WARNI [sqlalchemy.pool.QueuePool.0x...7310] [worker 26] Error closing cursor: cursor already closed

I set up the connection pool with the 'pool_recylce' setting set to 30mins, so that there are no connections lingering for more than 30 mins. The problem persists.

any ideas?

Update: I have posted the same question on stackoverflow and got an answer that worked. Have a look at https://stackoverflow.com/questions/6592137/sqlalchemy-fails-to-connect-to-db-after-server-is-idle-for-a-few-hours

We would like to create a template for a fairly standard stack in AWS. We need three layers.

1. Layer: Elastic Load Balancer

2. Layer: several web servers which are created / destroyed according to alarms triggered by the demand on the site

3. Layer: a database server

Instances on Layer 2 should know the host name of the database instance. Ideally I would like to get hold of the private IP of the database instance and pass it through user-data to the web servers.

Fn::GetAtt does not support the private ip (only the public)

I suppose an alternative would be to build the stack and afterwards to set manually the db private ip. It does though make our setup a bit less clean. We would ideally like everything to be described in the template. (even if this involves running a script through user-data)

Any suggestions?