use-http2 default value discrepancies in docs

[ktzsolt]

What happened:

Trying to figure out what the default value is for use-http2 ConfigMap setting is, documentation just says Enables or disables support in secure connections. https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#use-http2

When clicking on the nginx doc link for http2 I see that default value is off: https://nginx.org/en/docs/http/ngx_http_v2_module.html

When not setting use-http2 in the ingress-nginx-controller ConfigMap I see that http2 support is actuall turned on. Checking my ingress endpoints with curl -vvv I see in the logs:

ALPN, server accepted to use h2
Using HTTP2, server supports multiplexing
GET /myingress HTTP/2
HTTP/2 200

I can force http1.1 with curl -vvv --http1.1 and then I get http1.1 responses.

Checking one of the ingress-nginx pods nginx.conf file I see:

$ grep http2 nginx.conf
http2_max_concurrent_streams    128;
        http2 on;
        http2 on;

When I set use-http2: "true" in the ingress-nginx-controller ConfigMap the same happens.
When I set use-http2: "false" in the ingress-nginx-controller ConfigMap then I can not get http2 responses and I don't see http2 on in nginx.conf file.

What you expected to happen:

having the same default value for http2 as the base nginx software has or document the default value on https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#use-http2

NGINX Ingress controller version (exec into the pod and run nginx-ingress-controller --version.):

nginx/1.25.5

/kind documentation
/remove-kind bug

[k8s-ci-robot]

This issue is currently awaiting triage.

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[longwuyuan]

@ktzsolt which version of upstream NGINX introduced support for HTTP2 ?

[ktzsolt]

@ktzsolt which version of upstream NGINX introduced support for HTTP2 ?

https://nginx.org/en/docs/http/ngx_http_v2_module.html

The ngx_http_v2_module module (1.9.5) provides support fo HTTP/2.

1.9.5 was released in 2015
https://blog.nginx.org/blog/nginx-1-9-5

[github-actions]

This is stale, but we won't close it automatically, just bare in mind the maintainers may be busy with other tasks and will reach your issue ASAP. If you have any question or request to prioritize this, please reach #ingress-nginx-dev on Kubernetes Slack.