ynr/settings: add containerised local.py example

ynr/settings/local.py.container.example

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+# Only set DEBUG to True in development environments.
+DEBUG = True
+
+# This short, known value is insecure.
+SECRET_KEY = "development"
+
+# Certain errors are very noisy (obscuring the real problem) if this list is
+# empty.
+ADMINS = [("Dummy Admin", "[email protected]")]
+
+# This permits the site to be served at localhost:8080.
+ALLOWED_HOSTS = ['*']
+
+# This unpleasantness adds the container's internal IP to the list of those IPs
+# permitted to access the Django debug toolbar, which allows it to be enabled.
+# We believe the container's own IP needs to be in this list because of
+# something to do with the container networking, or the HTTP server gunicorn's
+# reverse-proxy setup, or both.
+# TODO: Replace with a better method, either here or by changing the
+# container/gunicorn setup. https://pypi.org/project/netifaces/ also exists,
+# but might not be considered "better".
+import socket
+s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+s.connect(("8.8.8.8", 80))
+INTERNAL_IPS = [ '127.0.0.1', str(s.getsockname()[0]) ]
+s.close()