Add support for NGINX Ingress 21+

Problem to solve

It looks like NGINX Ingress has changed the labels again, and is no longer detected in our metrics library.

The below label set was reported by a user in https://gitlab.com/gitlab-org/gitlab-ce/issues/50431#note_135267982, on version 0.22.

nginx_ingress_controller_bytes_sent_bucket{controller_class="nginx",controller_namespace="kube-ingress",controller_pod="nginx-ingress-controller-dhcxq",endpoint="metrics",exported_namespace="ci-vip",exported_service="review-vom-111-iup0em-chart",host="vip-review-vom-111-iup0em.demo.com",ingress="review-vom-111-iup0em-chart",instance="10.255.40.11:10254",job="nginx-ingress",le="+Inf",method="POST",namespace="kube-ingress",path="/",pod="nginx-ingress-controller-dhcxq",service="nginx-ingress-controller-metrics",status="200"}

We should add support for the new version.

Target audience

• Sasha, Software Developer, https://design.gitlab.com/research/personas#persona-sasha

• Devon, DevOps Engineer, https://design.gitlab.com/research/personas#persona-devon

• Sidney, Systems Administrator, https://design.gitlab.com/research/personas#persona-sidney

Further details

Proposal

Add support for the latest NGINX releases for response metrics.

What does success look like, and how can we measure that?

NGINX Ingress versions 21+ are correctly detected.

Links / references