nginx: Add log rotation script and cron job

roles/nginx/server/templates/nginx-logrotate.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+set -e
+
+umask 022
+
+[ -f /var/run/nginx.pid ] || exit 0
+
+SUFFIX="$(date +%Y%m%d-%H%M%S)"
+LOGS=""
+
+for log in "{{ nginx_logdir }}"/*.log ; do
+    [ -s "$log" ] || continue
+    mv "$log" "${log}.${SUFFIX}"
+    LOGS="${LOGS} ${log}.${SUFFIX}"
+done
+
+[ -z "$LOGS" ] && exit 0
+
+kill -USR1 "$(cat /var/run/nginx.pid)"
+sleep 5
+
+for log in $LOGS ; do
+    gzip "$log"
+done