Run nginx container on custom port, using env variable "NGINX_PORT=<80>"

Dockerfile

FROM nginx:latest
LABEL maintainer="Biarca"

COPY mysite.template /
CMD ["/bin/bash", "-c", "export NGINX_PORT=${NGINX_PORT:-80}; envsubst < /mysite.template > /etc/nginx/conf.d/default.conf && nginx -g 'daemon off;'"]

mysite.template

server {
    listen      \${NGINX_PORT};
    server_name  localhost;

    location / {
        root   /usr/share/nginx/html;
        index  index.html index.htm;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

Thanks for this - another great start for what I need. I'm planning on mirroring all the nginx images based on the seg3 value in this item in the lfccncf repository, using your trick with envsubst slightly abstracted via a script that will be the entrypoint.

As per https://hub.docker.com/_/nginx/ we can't just set NGINX_PORT as the author has noted in the README for this item.