Nginx Docker Container and getpwnam(“www-data”) problem

I am using nginx:1.10.1-alpine to run Nginx as a docker container. Today I have replaced the Nginx container and always got the status Restarting (1) Less than a second ago after starting the container.

With the command docker logs nginx I got the following error logs.

The error message basically means that the user www-data which I have defined in /etc/nginx/nginx.conf doesn’t exists in /etc/passwd. That makes sense, because nginx:1.10.1-alpine comes with a minimal setup. I my case I need the user www-data for other linked php-fpm containers. To fix the problem I just added the missing user during the container build.


Nginx and Cached CSS / JS files

Yesterday I had a pretty hard time with cached CSS / JS files on my developer environment. I supposed to review layout changes, but I always got the old CSS files. I have spent about 2 hours to find the reason. At the end the solution was to turn off the syscall sendfile in my virtual host configuration.

If you use Nginx as a reverse proxy to serve pages from an application server, you can leave sendfile turned off.


Reload Nginx Inside Docker Container

I am using docker for Nginx which is running with multiple virtual hosts. Sometimes I have to reload my updated nginx configurations, but I don’t want restart the container each time. Here is how you can reload your nginx without any downtime and without interrupting any connections.

1. Find your container name

Use docker ps to find your nginx container.

2. Reload Nginx

With docker exec -it {container_name} {command} you can directly access your container and execute commands. In my case the name of the container is nginx-server.