Using NGINX as a reverse proxy is an extremely common scenario. In fact that's what I currently run (with a support subscription), but will be evaluating moving to HAProxy if their tech dept does not provide a way to resolve this issue (which is actually a very big deal for me, and I was not aware)
This is Owen from NGINX. We have a workaround for this behavior (https://gist.github.com/thresheek/2fa6479ffb7aca710493), and are tracking a separate new feature request. Please submit a support ticket or send me an email, owen@nginx.com.
Thank you, I will be opening the ticket tomorrow. Regarding the gist you just posted, it seems this simply disables proxy_next_upstream for any and all non idempotent requests.
However what would really need to happen is to only disable proxy_next_upstream if data has been written or read from the backend(preferably configurable by backend or location for either of those two options). Right now you basically lose the redundancy in non-idempotent requests, and immediately return the error. Or maybe I read the configuration incorrectly.
