Add expires_at field to SignatureView response

[jjnesbitt]

Currently, the view for creating a temporary signature for GET requests looks like this

ResonantGeoData/django-rgd/rgd/rest/viewsets.py

Lines 60 to 64 in 417c920

	def post(self, request):
	signer = UserSigner()
	signature = signer.sign(user=self.request.user)
	param = getattr(settings, 'RGD_SIGNED_URL_QUERY_PARAM', 'signature')
	return response.Response({param: signature})

With the only field returned being signature. It'd be good to also include an expires_at field, which would indicate the unix timestamp at which this signature expires.

[banesullivan]

It'd be good to also include an expires_at field, which would indicate the unix timestamp at which this signature expires.

I'm also thinking that we should allow the user to specify how long they want the token to be valid to override our default value while setting some cap at like 1 month or something

[jjnesbitt]

It'd be good to also include an expires_at field, which would indicate the unix timestamp at which this signature expires.

I'm also thinking that we should allow the user to specify how long they want the token to be valid to override our default value while setting some cap at like 1 month or something

I don't see much wrong with that, although I'd think a month would be quite a long time for this, given how it's intended to be used.

Also, when someone makes a request for a new signature, are all previous signatures invalidated?