Disabling `must-revalidate` when serving static files via Inert about inert

[kanongil]

Unfortunately the must-revalidate parameter is currently hardcoded in hapi, and inert cannot change this. It would be nice if hapi had an option to customise this and add other parameters like immutable.

If you don't want to change hapi, the best option is to set the cache-control header yourself, which causes the default logic to be disabled. This can be done in a route-specific ext handler, eg.:

options: {
    …,
    ext: {
        onPostHandler(request, h) {

            const response = request.response;
            const ttl = Math.floor(response.settings.ttl, 1000);
            response.header('cache-control', `max-age=${ttl}, immutable`);

            return h.continue;
        }
    }
}

I guess inert could do this and expose an option, but I really think that this should be fixed in hapi itself.

FYI, otherwise is used when caching is disable for the response, eg. for responses to a POST request, or when the response ttl is 0.