Switch URL protocol for resource links to HTTPS

The parent project has an issue filed to make the resource links the same protocol as the request.

Change URL protocol in response data based on whether the request was made over HTTPS: https://github.com/phalt/swapi/issues/66

Since the swapi.dev server uses HTTPS (it even redirects HTTP to HTTPS) and the world has pretty much switched over to HTTPS, it probably makes sense to just do a simple straight switch to HTTPS. There’s little value in making the response intelligent based on the protocol of the request.

Currently the next field in responses uses the HTTP protocol:

GET https://swapi.dev/api/vehicles/?format=json

{
   "count": 39,
   "next": "http://swapi.dev/api/vehicles/?page=2&format=json",
   "previous": null,
   "results": [
      {
         "name": "Sand Crawler",
         "model": "Digger Crawler",
         "manufacturer": "Corellia Mining Corporation",
         "cost_in_credits": "150000",
         "length": "36.8 ",
         "max_atmosphering_speed": "30",

Following the next link can result in errors like:

Fetch API cannot load http://swapi.dev/api/vehicles/?page=2&format=json due to access control 

This problem would be resolved by using HTTPS in the next field:

   "next": "https://swapi.dev/api/vehicles/?page=2&format=json",

[leonidpodriz]

@Juriy Well, you’re right. But after HTTPS=on Django will stay on plain HTTP and reverse proxy will works correct.

Proofs from local testing:

This environment variable is uses only to build absolute URLs. I had search where HTTPS variable is using and not found more places despite this: https://github.com/django/django/blob/b626c289ccf9cc487f97d91c2a45cac096d9d0c7/django/http/request.py#L135

Django has a few more ways to make it return HTTPS URLs, but this way is the easiest and impact only one function (see above), not the whole application.

[leonidpodriz]

Hello, @Juriy. I am really glad to see your activity on this project. 😃

To make Django use HTTPS instead of HTTP, set HTTPS=on in environment variables.