Self-signed certificate generation.

By default the cerificate is valid for 30 days, reasonable. Also, using
-batch means the default values are used and the certificate is
generated without any input required.

Dockerfile

@@ -15,8 +15,7 @@ RUN rm -rf /etc/nginx/conf./* && \
                 -keyout /var/ssl/site.key \
                 -nodes \
                 -out /var/ssl/site.crt \
-                -days 2 \
-                -subj "/C=US/ST=IL/L=None/O=None/OU=None/CN=localhost/" && \
+                -batch && \
     setcap CAP_NET_BIND_SERVICE=+ep "$(command -v nginx)" && \
     chown nginx /var/ssl/site.*
 COPY www/ /var/www/