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NGF: Add document for upstream http2#2021

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bjee19 wants to merge 3 commits into
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bjee19:ngf/http2-appProtocol
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NGF: Add document for upstream http2#2021
bjee19 wants to merge 3 commits into
nginx:ngf-release-2.7from
bjee19:ngf/http2-appProtocol

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@bjee19

@bjee19 bjee19 commented Jun 3, 2026

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Proposed changes

Add document on supporting http2 to upstream through the appProtocol field on a Service.

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@bjee19 bjee19 requested a review from a team as a code owner June 3, 2026 05:49
@github-actions github-actions Bot added documentation Improvements or additions to documentation product/ngf Issues related to NGINX Gateway Fabric labels Jun 3, 2026
@bjee19

bjee19 commented Jun 3, 2026

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This is a shorter guide which is technically covering a Kubernetes concept (Service's appProtocol), however I couldn't find a suitable document to include this information in. So I decided to write a standalone document for it.

@bjee19 bjee19 requested a review from a team June 3, 2026 05:49
f5-summary: This guide shows you how to configure NGINX Gateway Fabric to proxy requests to upstream services over HTTP/2 by setting appProtocol to kubernetes.io/h2c on a Kubernetes Service port. Using HTTP/2 for upstream connections enables multiplexing and reduces latency for services that support it. This guide is for operators and developers who have NGINX Gateway Fabric installed and are familiar with Kubernetes Services and the Gateway API.
---

Learn how to configure NGINX Gateway Fabric to use HTTP/2 when proxying requests to upstream services using the Service `appProtocol`.

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appProtocol is a application protocol for a service port so this sentence seems misleading a bit?

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Suggested change
Learn how to configure NGINX Gateway Fabric to use HTTP/2 when proxying requests to upstream services using the Service `appProtocol`.
Learn how to configure NGINX Gateway Fabric to use HTTP/2 when proxying requests to upstream services.

I think should be enough here

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Changed to Learn how to configure NGINX Gateway Fabric to use HTTP/2 when proxying requests to upstream services using the Service port's appProtocol field. I still want to include the appProtocol field since I feel like its a core part.

Comment on lines +167 to +175
```nginx
location /coffee {
...
proxy_http_version 2;
proxy_pass http://default_coffee_80;
...
}
```

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so the curl doesn't return the protocol? or a different response to identify a http2 connection?

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The upstream application in this example doesn't respond back with http2 responses/ "doesn't speak http2" so it won't really work with a curl request. I don't really feel the need to show a response with a working http2-available backend, so I felt that just showing the nginx conf would suffice.

If you feel like its necessary to show a curl request, basically checking if the nginx conf proxy_http_version 2; works, then we can consider that, but I don't feel the need.

## Important Notes

- `kubernetes.io/h2c` is supported on HTTPRoutes and GRPCRoutes. It isn't supported on TLSRoutes.
- For NGINX to set `proxy_http_version 2` for a location, all valid backend references in the routing rule must have `appProtocol: kubernetes.io/h2c` set on their Service ports. If any valid backend doesn't use `kubernetes.io/h2c`, NGINX falls back to the default HTTP/1.1.

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i think this could be in the troubleshooting section

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Would that be in a different file? I feel like this is relevant enough to this feature that I would want it all contained in this single file. I can put it in a different section in the file if you think that would be better

Comment on lines +68 to +72
{{< call-out "note" >}}

Kubernetes is generally not recommended for hostile multi-tenant environments and NGINX is designed to treat upstreams as trusted. If you need a dataplane that doesn't treat upstreams as trusted, you may want to explore alternative solutions.

{{< /call-out >}}

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added this note here for the request by the user @salonichf5, do you have any thoughts? Should this even go in our docs here or maybe should it just live in our github docs somewhere? I don't really feel the need of highlighting this statement, and am on the border of if its necessary at all and might do more harm than good.

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