[Nginx] Expose specified port for Nginx in Dockerfile

When we build a custom docker image based on nginx docker image, the default lisenting port will be 8080. However, port 8080 is a quite popular, so sometimes I want to give a different port for my service. The below snippet of code is the solution.

FROM nginx
COPY ./public/ /usr/share/nginx/html
EXPOSE 1313
CMD ["/bin/sh", "-c", "sed -i 's/listen  .*/listen 1313;/g' /etc/nginx/conf.d/default.conf && exec nginx -g 'daemon off;'"]