https://github.com/fedora-infra/flask-healthz
Liveness and readiness endpoints for Flask
https://github.com/fedora-infra/flask-healthz
Last synced: 4 months ago
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Liveness and readiness endpoints for Flask
- Host: GitHub
- URL: https://github.com/fedora-infra/flask-healthz
- Owner: fedora-infra
- License: bsd-3-clause
- Created: 2020-05-06T09:29:40.000Z (almost 5 years ago)
- Default Branch: develop
- Last Pushed: 2024-04-15T22:15:08.000Z (12 months ago)
- Last Synced: 2024-04-22T00:42:07.329Z (12 months ago)
- Language: Python
- Size: 468 KB
- Stars: 20
- Watchers: 7
- Forks: 6
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Flask-Healthz
Define endpoints in your Flask application that Kubernetes can use as
[liveness and readiness probes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/).
## Setting it up
### Blueprint
Register the blueprint on your Flask application:
```python
from flask import Flask
from flask_healthz import healthz
app = Flask(__name__)
app.register_blueprint(healthz, url_prefix="/healthz")
```
Define the functions you want to use to check health. To signal an error, raise `flask_healthz.HealthError`.
```python
from flask_healthz import HealthError
def liveness():
pass
def readiness():
try:
connect_database()
except Exception:
raise HealthError("Can't connect to the database")
```
Now point to those functions in the Flask configuration:
```python
HEALTHZ = {
"live": "yourapp.checks.liveness",
"ready": "yourapp.checks.readiness",
}
```
It is possible to directly set callables in the configuration, so you could write something like:
```python
HEALTHZ = {
"live": lambda: None,
}
```
Check that the endpoints actually work:
```
$ curl http://localhost/yourapp/healthz/live
{"status": 200, "title": "OK"}
$ curl http://localhost/yourapp/healthz/ready
{"status": 200, "title": "OK"}
```
Now your can configure Kubernetes or OpenShift to check for those endpoints.
### Extension
You can also use the provided Flask extension to register the `healthz` blueprint:
```python
from flask import Flask
from flask_healthz import Healthz
app = Flask(__name__)
Healthz(app)
```
The rest of the configuration is identical.
The extension has an additional option, `no_log`, that can disable logging of the HTTP requests
handled by your healthz endpoints, to avoid cluttering your web log files with automated requests.
At the moment, only the [gunicorn](https://gunicorn.org/) web server is supported.
```python
Healthz(app, no_log=True)
```
## Examples
Here's an example of how you could use flask-healthz in OpenShift's `deploymentconfig`:
```yaml
kind: DeploymentConfig
spec:
[...]
template:
[...]
spec:
containers:
- name: yourapp
[...]
livenessProbe:
httpGet:
path: /healthz/live
port: 8080
initialDelaySeconds: 5
timeoutSeconds: 1
readinessProbe:
httpGet:
path: /healthz/ready
port: 8080
initialDelaySeconds: 5
timeoutSeconds: 1
```
Some projects that have setup flask-healthz:
- Noggin: https://github.com/fedora-infra/noggin/pull/287
- FASJSON: https://github.com/fedora-infra/fasjson/pull/81
## License
Copyright 2020-2021 Red Hat
Flask-Healthz is licensed under the same license as Flask itself: BSD 3-clause.
[](https://codecov.io/gh/fedora-infra/flask-healthz)