Event source returned unexpected content type ''

[matt-dutchie]

Describe the bug

Hello.

I'm attempting to update our code to use v7.0.2 of the ruby SDK. I'm receiving the following error when I try to boot up a client:

[2023-02-22T18:08:50] INFO  | [LDClient] Initializing stream connection
[2023-02-22T18:08:50] INFO  | Connecting to event stream at https://stream.launchdarkly.com/all
[2023-02-22T18:08:50] WARN  | Event source returned unexpected content type ''
...
# Times out, then retries ad nauseum

Tracing this bug backwards, I was able to reproduce starting in v6.0.0.

After doing a little code spelunking in the ld-eventsource plugin, I ran the following code to see if something weird is going on with the http request:

client = HTTP::Client.new()

sdk_key = # using our sdk key
headers = {
  "Accept"=>"text/event-stream",
  "Cache-Control"=>"no-cache",
  "User-Agent"=>"ruby-eventsource",
  "Authorization" => sdk_key
}

client.request("GET", "https://stream.launchdarkly.com/all", { headers: headers })

# => #<HTTP::Response/1.1 200 OK {"Date"=>"Thu, 23 Feb 2023 00:27:40 GMT", "Content-Type"=>"text/event-stream; charset=utf-8", "Transfer-Encoding"=>"chunked", "Connection"=>"close", "Accept-Ranges"=>"bytes", "Cache-Control"=>"no-cache, no-store, must-revalidate", "Etag"=>"\"9347c\"", "Ld-Region"=>"us-east-1", "Strict-Transport-Security"=>["max-age=31536000", "max-age=31536000"]}>

While not exactly analogous to your HTTP::Client usage within the ruby-eventsource plugin powering the connection, this seems to be at odds with the error case here: https://github.com/launchdarkly/ruby-eventsource/blob/68a3a91b70d13919a7b0fdcc5863483b3d52f802/lib/ld-eventsource/client.rb#L272

I'll keep digging but any help would be useful.

We are pegged to Faraday v1.10.0 and http v4.4.1 for dependency reasons.

Thank you.

[matt-dutchie]

After some more exploration, it appears that the issue is with this line in the ruby-eventsource library:

https://github.com/launchdarkly/ruby-eventsource/blob/main/lib/ld-eventsource/client.rb#L271

cxn.headers["content-type"] is evaluating to an empty string, while cxn.headers["Content-Type"] evaluates to the correct value (text/event-stream; charset=utf-8). Correcting this locally establishes the connection without issue.

[louis-launchdarkly]

Hello @matt-dutchie, thank you so much for the report and investigation. To clarify, the issue is that while the Ruby SDK can connect to LaunchDarkly's backend and get flag data, it keeps splitting out this warning in the logs because of the upper-lower cases mismatch that you identified - is that correct?

Keeping track of this issue with 190660.

[matt-dutchie]

@louis-launchdarkly Yea, it works after tweaking the casing on the header access. I've opened a PR against the other lib here: launchdarkly/ruby-eventsource#36

[matt-dutchie]

Ah -- sorry, I misunderstood your comment. We were not able to connect without this change, the casing was causing an error not a warning and the initialization of the client was timing out.

[matt-dutchie]

This should be fixed by my PR against ruby-eventsource, closing!

[keelerm84]

I will still need to cut a release for you for both the event source and the SDK before this is fully resolved. There are some internal blockers at the moment but I will work to get this done by early next week at the latest.

Thanks again for your contribution!

[keelerm84]

Sorry for the delay, but this has been fixed in 7.0.3