API should send Vary: Accept-Language header

[russss]

As the API sends cache headers and uses Accept-Language to determine which language to return, it should send the Vary: Accept-Language response header to stop the incorrect language being returned from the cache.

[russss]

Wait, this should be in osmose-frontend shouldn't it... I think you can move it.

[frodrigo]

I not sure how to do this with the fastAPI framework.

We should add this header in the response for all routes using the parameter langs: LangsNegociation = Depends(langs.langs).

[jocelynj]

Could we add this header with Apache?

For example, we are adding Cache-Control "public, immutable" according to https://github.com/osm-fr/osmose-frontend/blob/master/apache-site

[frodrigo]

Could we had this header with Apache?

I don't think so. Apache need it to know how to cache.