如何在 Nginx 配置中使用操作系统环境变量？

我如何在nginx配置中使用在操作系统中设置的环境变量？

例如设置的环境变量为ENVIRON=dev，APP_NAME=test

这是我的Dockerfile:

FROM openresty/openresty:alpine

RUN set -ex && \
    rm /etc/nginx/conf.d/default.conf

ADD nginx.conf /etc/nginx/
ADD custom.conf /etc/nginx/conf.d/

这是我的主nginx.conf

user  nginx;
worker_processes auto;
pcre_jit on;

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;

events {
    worker_connections  1024;
}

env ENVIRON;
env APP_NAME;
set_by_lua $environ 'return os.getenv("ENVIRON")';
set_by_lua $appname 'return os.getenv("APP_NAME")';

http {
    server_tokens off;
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;
    sendfile        on;
    keepalive_timeout  65;
    include /etc/nginx/conf.d/*.conf;
}

这是我来自/etc/nging/conf.d/的custom.conf

upstream app.$environ-$appname  {
      server $environ-$appname:80;
}
server {
    listen 80;
    server_name $hostname;
    error_log /dev/stdout info;
    access_log /dev/stdout;
    location / {
      proxy_redirect off;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
      add_header X-Info proxied;
      proxy_pass http://app.$environ-$appname;
    }
}

谢谢！