Django Database Connection Autoreconnect
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 tries to reconnect, instead of immediately raising an OperationException.
Why is this useful?
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 will 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.
How to install?
Just pull the library in using pip install django-dbconn-retry. Then add django_dbconn_retry to INSTALLED_APPS in your settings.py.
Signals
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 |
|---|---|
pre_reconnect |
Installs a hook of the type Callable[[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_reconnect |
Installs a hook of the type Callable[[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 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.
Settings
Here’s a list of settings available in django-dbconn-retry and their default values. You can change the value in your settings.py.
Setting |
Description |
|---|---|
MAX_DBCONN_RETRY_TIMES |
Default: 1 The max times which django-dbconn-retry will try. |
DBCONN_RETRY_DELAY |
Default: 0 The base delay in seconds before each retry attempt. Used as the initial delay and, together with DBCONN_RETRY_BACKOFF, controls the delay for subsequent retries. Set to 0 to retry immediately. |
DBCONN_RETRY_BACKOFF |
Default: 1 The multiplier applied to the delay after each retry. For example, with DBCONN_RETRY_DELAY=1 and DBCONN_RETRY_BACKOFF=2, the delays will be 1s, 2s, 4s, etc. Note that delays grow exponentially and can become very large for higher values. For example, with DBCONN_RETRY_DELAY=10, DBCONN_RETRY_BACKOFF=3 and MAX_DBCONN_RETRY_TIMES=10, the final retry would wait on the order of tens of hours. Choose these settings carefully if very long waits are not acceptable for your deployment. |
Contributors
Many thanks to people who have contributed to this library:
durant (@zhangzhw8)
Shawn Zivontsis (@shawnz)
License
Copyright (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 may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1 maintainer
Metadata
1 maintainer
Release files for django-dbconn-retry 0.3.1
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Built distribution (wheel)
| File | Interpreter | ABI | Platform | Actions Reset |
|---|---|---|---|---|
| django_dbconn_retry-0.3.1-py3-none-any.whl | Python 3 | none | any | Details for django_dbconn_retry-0.3.1-py3-none-any.whl |
Release files / django_dbconn_retry-0.3.1-py3-none-any.whl
| Download URL | django_dbconn_retry-0.3.1-py3-none-any.whl |
|---|---|
| Size | 9.0 kB |
| Tags | Python 3 |
|
SHA-256 checksum How to use checksums |
d4b64d915440c3e5902ef8edf836366a6f4c4f027d34902135d7335233d6dbba
|
|
BLAKE2b-256 checksum How to use checksums |
5d2a4ac8cf6fa6ae3f127ac7ecfa4c2c712129b3803978d3fecc4d127024e016
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
No |
| Uploaded via |
twine/6.2.0 CPython/3.13.5
|
Security for django-dbconn-retry 0.3.1
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
No provenance found
None of the files in this release were uploaded with provenance metadata.
A note on package security
PyPI is a repository for distributing packages, not a service for auditing them. While third-party security researchers and our staff do their best to detect and remove malicious packages, PyPI cannot guarantee the quality, security or suitability of any given package.
To learn more about protecting yourself from malicious actors, visit our package security documentation.
