Warn when database config isn't readable

[lunkwill42]

This code handles configuration of the DATABASES Django setting from NAV's standard db.conf file:

nav/python/nav/django/settings.py

Lines 51 to 70 in 6b359de

	# Database / ORM configuration
	try:
	_appname = os.path.basename(sys.argv[0])
	_host, _port, _name, _user, _password = get_connection_parameters('django')
	DATABASES = {
	'default': {
	'NAME': _name,
	'ENGINE': 'django.db.backends.postgresql_psycopg2',
	'HOST': _host,
	'PORT': _port,
	'USER': _user,
	'PASSWORD': _password,
	'CONN_MAX_AGE': 300, # 5 minutes
	'OPTIONS': {
	'application_name': _appname or 'NAV',
	},
	}
	}
	except (IOError, OSError):
	pass

It quietly ignores issues with reading the db.conf config, to ensure NAV code can still be imported during development or unit testing, when no database is actually running.

However, this masks issues with getting parts of NAV to run in production. E.g. if the NAV web app doesn't run with the necessary privilege level to read db.conf, the app will crash with only a generic Django ImproperlyConfigured error for the DATABASES setting - leaving the user to figure out for themselves what the actual underlying problem is.

Solution

The exception handler needs to be there, due to the reasons described above, but it should at least output a warning containing a description of the caught exception, so the problem will be easier to track down for an end user.