Package: django-dbconn-retry
Django Database Connection AutoreconnectThis library monkeypatchesdjango.db.backends.base.BaseDatabaseWrapperso
that when a database operation fails because the underlying TCP connection was
already closed, it first tried to reconnect, instead of immediately raising
anOperationException.Why is this useful?I useHAProxyas a load-balancer in front of my PostgreSQL databases all
the time, sometimes in addition topgbouncer. Even though you can mostly
prevent surprises by enabling TCP keep-alive packets throughtcpka,clitcpkaandsrvtcpka, I still encounter situations where the
underlying TCP connection has been closed through the load-balancer. Most often
this results indjango.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 usingHashicorp Vault, where
credentials for a database connection can expire at any time and then need to
be refreshed from Vault.How to install?Just pull the library in usingpip installdjango-dbconn-retry. Then adddjango_dbconn_retrytoINSTALLED_APPSin yoursettings.py.SignalsThe library provides an interface for other code to plug into the process to,
for example, allow12factor-vaultto refresh the database credentials
before the code tries to reestablish the database connection. These are
implemented usingDjango Signals.SignalDescriptionpre_reconnectInstalls a hook of the typeCallable[[type,BaseDatabaseWrapper], None]that will be called before the library tries to
reestablish a connection. 12factor-vault uses this
to refresh the database credentials from Vault.post_reconnectInstalls a hook of the typeCallable[[type,BaseDatabaseWrapper], None]that will be called after the library tried to
reestablish the connection. Success or failure has
not been tested at this point. So the connection
may be in any state.Both signals send a parameterdbwrapperwhich points to the current instance
ofdjango.db.backends.base.BaseDatabaseWrapperwhich allows the signal
receiver to act on the database connection.LicenseCopyright (c) 2018, Jonas Maurus
All rights reserved.Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.Neither the name of the copyright holder nor the names of its contributors
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