This library monkeypatches django.db.backends.base.BaseDatabaseWrapper
so that when a database operation fails because the underlying TCP connection was already closed, it first tried to reconnect, instead of immediately raising an OperationException
.
I use HAProxy as a load-balancer in front of my PostgreSQL databases all the time, sometimes in addition to pgbouncer
. Even though you can mostly prevent surprises by enabling TCP keep-alive packets through tcpka, clitcpka and srvtcpka, I still encounter situations where the underlying TCP connection has been closed through the load-balancer. Most often this results in
django.db.utils.OperationalError: server closed the connection unexpectedly
This probably means the server terminated abnormally before or while
processing the request.
This library patches Django such that it try to reconnect once before failing.
Another application of this is when using Hashicorp Vault, where credentials for a database connection can expire at any time and then need to be refreshed from Vault.
Just pull the library in using pip install django-dbconn-retry
. Then add django_dbconn_retry
to INSTALLED_APPS
in your settings.py
.
The library provides an interface for other code to plug into the process to, for example, allow 12factor-vault to refresh the database credentials before the code tries to reestablish the database connection. These are implemented using Django Signals.
Signal | Description |
---|---|
|
Installs a hook of the type |
|
Installs a hook of the type |
Both signals send a parameter dbwrapper
which points to the current instance of django.db.backends.base.BaseDatabaseWrapper
which allows the signal receiver to act on the database connection.
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