Http.request etag cache issue

Questions
1

I’m following the example here to cache files but it seems there’s an issue with If-None-Match. When having it and without request options, the server always return 400 bad request. I guess the If-None-Match header is duplicated.

local function get_http_request_headers(name)
    local data = load_http_response_headers(name)
    local headers = {}
    for k, v in pairs(data) do
        if string.lower(k) == 'etag' then
            headers['If-None-Match'] = v
        elseif string.lower(k) == 'last-modified' then
            headers['If-Modified-Since'] = v
        end
    end
    return headers
end
2

What makes you think it is duplicated?

Is it your own server? Can you debug the request somehow?

3

I’m using Nginx for serving files and it rejects requests having duplicate headers.
When adding either Host or If-None-Match to headers, it causes error 400 bad request. It doesn’t happen when I send with options {ignore_cache = true}.

After checking game.project Network section, I see there’s Http Cache Enabled set as default. I think it does something with etag, so causing duplicate header.

4

You’re right. I knew we had some ETag handling but forgot about the details. The HTTP client will automatically handle ETags in it’s cache and send a If-None-Match request header which explains the duplicate:

So it seems like you are doing duplicate work of handling the ETag also in your client code?

Side-note: We have this feature request to add more cache control options:

5

I didn’t realize it until I found my app couldn’t load new updates because of the nginx error 400. In testing environment I don’t use nginx so couldn’t see this issue. Also I actually didn’t know that Defold has etag cache handling by default. So my suggestion is that either warn users about this duplication or just handle to discard/merge this header in case users add it

6

Yeah, we can perhaps handle it in the http_client code. We should at least better document which headers that we set. Could you please create a ticket on GitHub for this issue? Thanks!

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