I think it's the right solution, just taking a bit more time to review it.

Codecov Report

Merging #1032 into master will increase coverage by 0.2%.
The diff coverage is 65.41%.

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Using toStrictEntity seems to be the "standard" solution to this problem (see comments on https://groups.google.com/forum/#!topic/akka-user/v-jNYPkKVCU, akka/akka-http#117) but there seems to be a performance impact (see eclipse-ditto/ditto#412) and some of the suggested fixes which are nearly 2 years old have not been merged.

I think using toStrictEntity, but with a shorter time-out (5 seconds instead of 30, since all our API requests are small) should be fine, but another option is just to avoid matching on multiple formField extractors and do something like:

                      path("connect") {
                        formFields("uri".as[NodeURI].?, nodeIdFormParam.?, "host".as[String].?, "port".as[Int].?) { (uri_opt, nodeId_opt, host_opt, port_opt) =>
                          (uri_opt, nodeId_opt, host_opt, port_opt) match {
                            case (Some(uri), None, None, None) => complete(eclairApi.connect(Left(uri)))
                            case (None, Some(nodeId), Some(host), _) => complete(eclairApi.connect(Left(NodeURI(nodeId, HostAndPort.fromParts(host, port_opt.getOrElse(NodeURI.DEFAULT_PORT))))))
                            case (None, Some(nodeId), None, None) => complete(eclairApi.connect(Right(nodeId)))
                            case _ => reject(MalformedFormFieldRejection("connect", "You must either provide field 'uri' or field 'nodeId' with optional fields 'host' and 'port'"))
                          }
                        }

This is much closer to what we have and there's only 1 or 2 places where we would need to do this. WDYT ?

I like the suggestion of not matching on multiple formFields if we can do that it's better than the workaround.

another option is just to avoid matching on multiple formField extractors and do something like:

It's less elegant than what we have now, but if that solves the issue and saves us from using timeouts, then I'm all for it.

withChannelIdentifier makes it quite hard to apply the change, especially in places like /close where we do match multiple formFields because of the channel identifier extraction that has been factored out. All the endpoints where we have

 withChannelIdentifier { channelIdentifier =>
   formField( fieldA, fieldB ) { 
      // complete
   }
 }

We're matching multiple formFields and it would become:

 formField(shortChannelId.?, channelId.? fieldA, fieldB ) { 
    case (Some(shortId), None, fieldA, fieldB) => // complete
    case (None, Some(channelId), fieldA, fieldB) => // complete
 }

And I missed that there is another form field for the API timeout....

Looks ok, hope there won't be side effects !