Make nginx port configurable

Author: bjw-s

.docker/nginx.conf

@@ -38,8 +38,8 @@ http {
     resolver 127.0.0.11 ipv6=off;
 
     server {
-        listen       80;
-        listen  [::]:80;
+        listen       ${NGINX_PORT};
+        listen  [::]:${NGINX_PORT};
         server_name  localhost;
 
         location / {

.docker/scripts/90-envsubst-on-nginx-conf.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env sh
+
+set -ex
+
+config_file="/etc/nginx/nginx.conf"
+
+tmpfile=$(mktemp)
+envsubst '${NGINX_PORT}' < "$config_file" > "$tmpfile"
+mv "$tmpfile" "$config_file"

Dockerfile

@@ -1,6 +1,8 @@
 FROM nginxinc/nginx-unprivileged:alpine-slim AS prod
 
-EXPOSE 8080
+ENV NGINX_PORT=80
+
+EXPOSE 80
 
 COPY --chmod=755 .docker/scripts/ /docker-entrypoint.d/
 COPY --chown=nginx:root .docker/nginx.conf /etc/nginx/