Heres a cute little pattern I threw together when writing sixpack. Im assuming youre using Werkzeug, but you could do the same thing with Flask, or pure WSGI.
First step is to write a little decorator that youre going to decorate your route handlers with. Its pretty straight forward. Here I used the decorator package to simplify things, but you can just do it in pure python if you dont need the additional dependency.
import decorator
from redis import ConnectionError
@decorator.decorator
def service_unavailable_on_connection_error(f, *args, **kwargs):
try:
return f(*args, **kwargs)
except ConnectionError:
return json_error({\"message\": \"redis is not available\"}, None, 503)
Its simply going to try to run the method you decorated, and catch a Redis ConnectionError. You could do this for any datastore, or anything else thats prone to complete failure. In this example, json_error() is a simple helper method that returns a JSON response with the correct Content-Type, status, etc. headers.
Then, in your server you can have something like this:
def __init__(self, redis_conn):
self.redis = redis_conn
self.url_map = Map([
Rule(/_status, endpoint=status),
])
… more werkzeug boilerplate
@service_unavailable_on_connection_error
def on_status(self, request):
self.redis.ping()
return json_success({version: __version__}, request)
If self.redis.ping() throws ConnectionError the decorator will catch it, and return the failing JSON. So, like the title says, nothing groundbreaking, but cute and might save you a few lines.