Running NGINX on Heroku with Docker

Docker is a great way to manage your NGINX deployments. Heroku is a great place to deploy Docker. While many of the buildpacks on Heroku use NGINX and can be configured to also serve as a reverse proxy, it sometimes is useful to run NGINX on its own.

The setup and config are about as easy as it gets. First, create a Dockerfile as shown below.

FROM nginx

COPY nginx.conf /etc/nginx/conf.d/default.conf

CMD sed -i -e 's/$PORT/'"$PORT"'/g' /etc/nginx/conf.d/default.conf && nginx -g 'daemon off;'

The one thing to notice is that I am using sed to replace the string $PORT in the nginx.conf file with the environmental variable PORT. This is because Heroku assigns a port to the dyno when it is started and handles the routing. So you can’t just set a fixed port like 443 in the config.

Next, create your nginx.conf file.

server {
    listen $PORT;

    location / {
        proxy_pass         http://example.com;
        proxy_redirect     off;
        proxy_set_header   X-Real-IP $remote_addr;
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header   X-Forwarded-Host $server_name;
    }
}

Next, create an app in Heroku and deploy the container by running the following commands.

Note you need to login to Heroku (heroku login and to the container service (heroku container:login) through the CLI before you run the next commands.

docker build -t web .
heroku container:push web --app <APPNAME>
heroku container:release web --app <APPNAME>

And that’s it, you now have NGINX deployed as a Docker container on Heroku.