Implement HEAD queries

[thbar]

When playing with data, it is very common to use curl -I (aka --head) to fetch only the headers.

Currently doing so on this app will return a 404, which can be a bit confusing too to newcomers.

I am unsure how costly it would be to implement that at the moment given my current knowledge of Actix.

Maybe there is a nice trick in Actix to ensure most GET queries can also be transformed to HEAD more or less automatically.

Less urgent than other enhancements, but still nice to have!

[thbar]

BTW, one trick to still show headers is to override the method after passing -I like this:

$ curl -I -X GET https://tr.transport.data.gouv.fr
HTTP/1.1 200 OK
content-length: 17808
content-type: application/json
date: Mon, 18 Jan 2021 10:49:47 GMT
Sozu-Id: 3c232174-837f-4e93-be84-3ee81aff10e4

(source: https://stackoverflow.com/a/38679650)