proxy-request-buffering: "off" ignored; request body is fully buffered before sending to backend

[gadekrushna]

What happened: I am trying to implement a streaming scenario where the client sends data in chunks to the backend. I need the Ingress Controller to disable buffering and pass the chunks immediately to the backend service.

I have applied the standard proxy-request-buffering: "off" annotation, along with configuration snippets to force header passthrough. However, NGINX is still buffering the entire request body. The backend only receives the request once the client has finished transmitting the entire body.

What I expected to happen: With nginx.ingress.kubernetes.io/proxy-request-buffering: "off", NGINX should not buffer the request body. It should stream the data to the backend as it is received from the client.

How to reproduce it:

1. Deploy a backend service that logs timestamped receipt of data chunks.
2. Deploy an Ingress resource with the annotations listed below.
3. Send a large file or stream data using a chunked client with HTTP1.1 and transfer encoding header as chunked.
4. Observe that the backend receives no data until the upload is 100% complete.

Ingress Controller version: ingress-nginx-4.11.3

Kubernetes version: 1.31.11

Cloud provider: Azure AKS

Load Balancer: No load balancer present request directly comes to ingress controller

annotations:

  # 1. Disable Request Buffering (Uploads)
  nginx.ingress.kubernetes.io/proxy-request-buffering: "off"
  
  # 2. Disable Response Buffering (Downloads/Streaming back to client)
  nginx.ingress.kubernetes.io/proxy-buffering: "off"
  
  # 3. Allow unlimited body size
  nginx.ingress.kubernetes.io/proxy-body-size: "0"
  
  # 4. Increase timeouts so the stream doesn't cut off
  nginx.ingress.kubernetes.io/proxy-read-timeout: "3600"
  nginx.ingress.kubernetes.io/proxy-send-timeout: "3600"

[k8s-ci-robot]

This issue is currently awaiting triage.

If Ingress contributors determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

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Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[Gacko]

ingress-nginx-4.11.3 implies controller v1.11.3, which is no longer supported. Please update to a supported version (v1.13, v1.14) and try to reproduce your issue.