gunicorn/docs/content/custom.md
2026-01-23 01:20:03 +01:00

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<span id="custom"></span>
# Custom Application
!!! info "Added in 19.0"
Use Gunicorn as part of your own WSGI application by subclassing
`gunicorn.app.base.BaseApplication`.
Example: create a tiny WSGI app and load it with a custom application:
```text
--8<-- "examples/standalone_app.py"
```
## Using server hooks
Provide hooks through configuration, just like a standard Gunicorn deployment.
For example, a `pre_fork` hook:
```python
def pre_fork(server, worker):
print(f"pre-fork server {server} worker {worker}", file=sys.stderr)
if __name__ == "__main__":
options = {
"bind": "127.0.0.1:8080",
"workers": number_of_workers(),
"pre_fork": pre_fork,
}
```
## Direct usage of existing WSGI apps
Run Gunicorn from Python to serve a WSGI application instance at runtime—useful
for rolling deploys or packaging with PEX. Gunicorn exposes
`gunicorn.app.wsgiapp`, which accepts any WSGI app (for example a Flask or
Django instance). Assuming your package is `exampleapi` and the application is
`app`:
```bash
python -m gunicorn.app.wsgiapp exampleapi:app
```
All CLI flags and configuration files still apply:
```bash
# Custom parameters
python -m gunicorn.app.wsgiapp exampleapi:app --bind=0.0.0.0:8081 --workers=4
# Using a config file
python -m gunicorn.app.wsgiapp exampleapi:app -c config.py
```
For PEX builds use `-c gunicorn` at build time so the packaged app accepts the
entry point at runtime:
```bash
pex . -v -c gunicorn -o compiledapp.pex
./compiledapp.pex exampleapi:app -c gunicorn_config.py
```