Using Nginx Templates for building custom container images

Docerfile

FROM nginx:1.19-alpine-perl
ENV NGINX_ENVSUBST_OUTPUT_DIR=/etc/nginx
COPY my-nginx.conf.template /etc/nginx/templates/

docker-compose.yaml

version: '3'

services:
  app:
    build: .
    environment:
       INGRESS_HOSTNAME: git.example.com
       BACKEND_HOSTNAME: 192.168.11.34

my-nginx.conf.template

user  nginx;
worker_processes  auto;

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

events {
    worker_connections  1024;
}                                                                                                                                         

http {
    # 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;
    #tcp_nopush     on;
    keepalive_timeout  65;
    #gzip  on;
    server {
      listen 80;
      location / {
          proxy_set_header Host "$INGRESS_HOSTNAME";
          proxy_pass http://$BACKEND_HOSTNAME;
          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      }
   }
}