Add support for STATUS_LISTEN_PORT env var

[rohvani]

This PR adds support to nginx-proxy so that you can specify which port that it'll listen on for the status/metrics page.

Depended on by https://github.com/secondlife/conductor-poc so that we can have reverse-proxies to backbonecommon and counter without relying on redirects through the ELB.

[Copilot]

Pull Request Overview

Adds configurability for the NGINX status page port via a new STATUS_LISTEN_PORT environment variable.

• Reads STATUS_LISTEN_PORT in the NGINX status config template instead of hard-coding 8091.
• Updates documentation (README) to describe the new variable and its default.
• Sets a default in the Dockerfile and adjusts the Datadog label to reference the new variable.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/etc/nginx/conf.d/status.conf.template	Changed listen 8091; to use {{ .Env.STATUS_LISTEN_PORT }}
README.md	Added STATUS_LISTEN_PORT to the env var table and usage section
Dockerfile	Defined ENV STATUS_LISTEN_PORT=8091 and updated Datadog label

Comments suppressed due to low confidence (3)

README.md:20

• [nitpick] The table entry for STATUS_LISTEN_PORT is missing an example value—consider adding one (e.g., 9090) to illustrate its usage.

| `STATUS_LISTEN_PORT` | nginx status port | No | 8091 | | 

README.md:70

• [nitpick] For consistency and clarity, wrap the variable reference in code ticks, e.g., http://localhost:`${STATUS_LISTEN_PORT}`/nginx_status.

http://localhost:${STATUS_LISTEN_PORT}/nginx_status.

Dockerfile:14

• There are no tests verifying that STATUS_LISTEN_PORT is correctly applied to the NGINX configuration; consider adding an integration or template‐rendering test.

ENV STATUS_LISTEN_PORT=8091

[Copilot]

If STATUS_LISTEN_PORT is unset, this will emit an invalid listen directive. Consider using a default/fallback (e.g., via Sprig’s default function) or validating the variable before template rendering.

[Copilot]

The default port (8091) is defined in multiple places (Dockerfile, template, docs); consider centralizing this default or referencing a single source to avoid drift.

Suggested change

	ENV STATUS_LISTEN_PORT=8091
	ARG DEFAULT_STATUS_LISTEN_PORT=8091
	ENV STATUS_LISTEN_PORT=$DEFAULT_STATUS_LISTEN_PORT