# 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)
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"description": "# Flask-Healthz\n\nDefine endpoints in your Flask application that Kubernetes can use as\n[liveness and readiness probes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/).\n\n\n## Setting it up\n\n### Blueprint\n\nRegister the blueprint on your Flask application:\n\n```python\nfrom flask import Flask\nfrom flask_healthz import healthz\n\napp = Flask(__name__)\napp.register_blueprint(healthz, url_prefix=\"/healthz\")\n```\n\nDefine the functions you want to use to check health. To signal an error, raise `flask_healthz.HealthError`.\n\n```python\nfrom flask_healthz import HealthError\n\ndef liveness():\n pass\n\ndef readiness():\n try:\n connect_database()\n except Exception:\n raise HealthError(\"Can't connect to the database\")\n```\n\nNow point to those functions in the Flask configuration:\n\n```python\nHEALTHZ = {\n \"live\": \"yourapp.checks.liveness\",\n \"ready\": \"yourapp.checks.readiness\",\n}\n```\n\nIt is possible to directly set callables in the configuration, so you could write something like:\n\n```python\nHEALTHZ = {\n \"live\": lambda: None,\n}\n```\n\nCheck that the endpoints actually work:\n\n```\n$ curl http://localhost/yourapp/healthz/live\n{\"status\": 200, \"title\": \"OK\"}\n$ curl http://localhost/yourapp/healthz/ready\n{\"status\": 200, \"title\": \"OK\"}\n```\n\nNow your can configure Kubernetes or OpenShift to check for those endpoints.\n\n### Extension\n\nYou can also use the provided Flask extension to register the `healthz` blueprint:\n\n```python\nfrom flask import Flask\nfrom flask_healthz import Healthz\n\napp = Flask(__name__)\nHealthz(app)\n```\n\nThe rest of the configuration is identical.\n\nThe extension has an additional option, `no_log`, that can disable logging of the HTTP requests\nhandled by your healthz endpoints, to avoid cluttering your web log files with automated requests.\nAt the moment, only the [gunicorn](https://gunicorn.org/) web server is supported.\n\n```python\nHealthz(app, no_log=True)\n```\n\n## Examples\n\nHere's an example of how you could use flask-healthz in OpenShift's `deploymentconfig`:\n\n```yaml\nkind: DeploymentConfig\nspec:\n [...]\n template:\n [...]\n spec:\n containers:\n - name: yourapp\n [...]\n livenessProbe:\n httpGet:\n path: /healthz/live\n port: 8080\n initialDelaySeconds: 5\n timeoutSeconds: 1\n readinessProbe:\n httpGet:\n path: /healthz/ready\n port: 8080\n initialDelaySeconds: 5\n timeoutSeconds: 1\n```\n\nSome projects that have setup flask-healthz:\n\n- Noggin: https://github.com/fedora-infra/noggin/pull/287\n- FASJSON: https://github.com/fedora-infra/fasjson/pull/81\n\n\n## License\n\nCopyright 2020-2021 Red Hat\n\nFlask-Healthz is licensed under the same license as Flask itself: BSD 3-clause.\n\n\n[](https://codecov.io/gh/fedora-infra/flask-healthz)\n\n",
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