Transfer-Encoding: chunked causes error

[nheidloff]

Hi, I've built a Spring Boot Docker container: https://github.com/nheidloff/openwhisk-debug-java

When I use the out of the box Spring functionality to build REST endpoints "Transfer-Encoding: chunked" is returned as header. When the container is deployed to the IBM Cloud I get the following error when invoking it: “The action did not produce a valid response and exited unexpectedly.”

I couldn't find a good way to get Spring Boot not to return this header. Instead I used a workaround/hack where the length of the output is calculated and then set in the content length header which causes the transfer encoding header to disappear. https://github.com/nheidloff/openwhisk-debug-java/blob/master/spring/src/main/java/docker/Function.java#L42

Since someone else ran into the same issue jthomas/ow#2, I'm wondering whether this can be changed on the OpenWhisk side?

[markusthoemmes]

Should be supportable. This could be a valuable first step for us to get into streaming!

We "just" need to make sure the HTTP client used in the invoker supports chunking and takes all the chunks before returning.

[rabbah]

it's all just a matter of code 😅

[ddragosd]

Just bumped into this issue as well (thanks @tysonnorris for pointing to it). I was debugging locally a blackbox Go action that was showing in the Invoker logs as NoResponseReceived(). When debugging locally OW I noticed that https://github.com/apache/incubator-openwhisk/blob/master/common/scala/src/main/scala/org/apache/openwhisk/core/containerpool/ApacheBlockingContainerClient.scala#L112 doesn't handle chunked responses.

While we decide what to do about chunked responses from actions, a good intermediary step might be to document this aspect to developers, so they force non chunked responses ?