scalaj-http | OAuth | OAuth library

Assuming that you are using JaCoCo with cobertura coverage you need to declare the dependencies and the plugin to run the command mvn cobertura:cobertura.

Future#sequence should execute the HTTP requests in parallel?

First of all, Future#sequence doesn't execute anything. It just produces a future that completes when all parameters complete. Evaluation (execution) of constructed futures starts immediately If there is a free thread in the EC. Otherwise, it simply submits it for a sort of queue. I am sure that in the first case you have single thread execution of futures.

println(scala.concurrent.ExecutionContext.Implicits.global) -> parallelism = 6

Don't know why it is like this, it might that other 5 thread is always busy for some reason. You can experiment with explicitly created new EC with 5-10 threads.

The difference with the Async case that you don't create a future by yourself, it is provided by the library, that internally don't block the thread. It starts the async process, "subscribes" for a result, and returns the future, which completes when the result will come.

Actually, async lib could have another EC internally, but I doubt.

Btw, Futures are not supposed to contain slow/io/blocking evaluations without blocking. Otherwise, you potentially will block the main thread pool (EC) and your app will be completely frozen.

In --packages you have com.typesafe.play:play-json:2.4.0 instead of com.typesafe.play:play-json_2.11:2.4.0 so you are fetching content from

https://repo1.maven.org/maven2/com/typesafe/play/play-json/2.4.0/

instead of

https://repo1.maven.org/maven2/com/typesafe/play/play-json_2.11/2.4.0/

If you're using default args for the constructors of a case class, it's much more idiomatic Scala to define them like this:

case class AddCount ( firstP: String = "default", count: Int = 1)

This is syntactic sugar that basically gives you the following for free:

Turns out the socket was being closed remotely by the Ingress controller running in front of the Kubernates environment where the Elasticsearch instance is running. It was set to the default of a one minute timeout.