information request: long polling seem's bugged on 304 http status code.

[floriangasc]

Expected Behavior

• long polling switch to regular polling in case of 304 http status code.
• this behavior come from line 340 of download.go: Content-type Header is not in reponse in case of 304 (according https://datatracker.ietf.org/doc/html/rfc7232#section-4.1). so «longPoll» switch from true to false.
• Same un case of error occured, longPoll is lost.

Actual Behavior

304 http status without content-type header should not change mode from long polling to regular polling.

Steps to Reproduce the Problem

the etag of foo.tar.gz is : "61751cfa-2c61e2"

opa polling config:

services:
  - name: open-policy-agent-registry
    url: http://127.0.0.1:8075/opa-registry-bundle/

bundles:
  authz:
    service: open-policy-agent-registry
    resource: foo-bundle.tar.gz
    polling:
      long_polling_timeout_seconds: 60

opa bundle server (i use openresty)

   lua_shared_dict revision_identifiers 10m;
    init_by_lua_block {
      ngx.shared.revision_identifiers:set("current_revision_identifier", '61751cfa-2c61e2')
    }

    server  {
    listen  8075 ;
        location ~ ^/opa-registry-bundle-revision/(?<revision_identifier>[^/]+) {
           access_by_lua_block {
              local revision_identifier = ngx.var['revision_identifier']
              local revision_identifiers = ngx.shared.revision_identifiers
              revision_identifiers:set("current_revision_identifier", revision_identifier)
           }
        }

        location /opa-registry-bundle/ {
          access_by_lua_block {
            local h = ngx.req.get_headers()
            local prefer_header = h['prefer']
            local etag = h['if-none-match']
            if prefer_header then
              local wait_in_second=string.match(prefer_header, "wait=([%d]+)")
              if wait_in_second then
                local wait_in_second_number = tonumber(wait_in_second)
                if wait_in_second_number then
                  local revision_identifiers = ngx.shared.revision_identifiers
                  local i = 0
                  while i < wait_in_second_number do
                    local revision_identifier = revision_identifiers:get("current_revision_identifier")
                    if revision_identifier == nil or  etag == nil then break end
                    local new_bundle = (revision_identifier == nil and etag == nil) or  '"'..revision_identifier..'"' ~= etag
                    if new_bundle then
                       ngx.header['Etag'] = '"'..revision_identifier..'"'
                       break;
                    end
                    ngx.sleep(2);
                    i = i + 2
                  end
                end
              end
             end
          }
           alias /tmp/FOO/;
           types { } default_type "application/vnd.openpolicyagent.bundles";
        }
    }

Additional Info

For solve issue i have

• initialize longPoll in loop function

longPoll := false
if d.config.Polling.LongPollingTimeoutSeconds != nil {
        longPoll = true
}

• pass longPoll var to oneShot and and download function
• hange go longPoll: isLongPollSupported(resp.Header), to longPool : longPoll in case of 304 status in download function.

question:

• if it's not a bug, but wanted behavior, sorry for this issue. And i have missed something for use long polling ? 
• If it's a bug, i make a pull request (it's quick and dirty fix, and i not found yet better way)

[stale]

This issue has been automatically marked as inactive because it has not had any activity in the last 30 days.

[ashutosh-narkar]

PR# #3926