Maintaining Concerto Digital Signage Step 2 – Cache Management

In the last post we discussed log rotation to prevent Concerto from filling up the hard drive of the VM which would keep the application from starting.  There is an additional step you should take to ensure you don’t encounter problems with space down the road, and that is clearing the applications cache.  The cache is not as dangerous as the production log, which can grow very quickly.  The cache will eventually become a problem but it would be quite a while before it reached danger levels, depending on how big and distributed your Concerto Digital Signage deployment is.  The first thing you need to know is where the cache is located.  The cache is located in the following directory:

/usr/share/concerto/tmp/cache

You can manually clear the cache by traversing to that directory above and using the following command:

sudo bundle exec rake tmp:clear

I think a better way to do it is to either setup a cron job to execute that command on a daily basis or have a script run that executes the cache clearing command.  Here is a simple script I wrote that would be executed on the VM that provides a status of Concerto (is it up, it fails to send if down), clears the cache, and reports free disk space back via a log file that is emailed daily (or however often you choose).  You will need the following packages installed on the VM “ssmtp” (to send the email), as well as “curl” and “wget” (for connectivity testing).   You also need to setup ssmtp to run via no password for sudoers (I can do a post on that later but you should be able to Google how to do that pretty easily).  I called the script “status_concerto.sh” and it runs daily via a cron job.

#/bin/bash
# CONCERTO STATUS SCRIPT v1
# Author: Rob Flemen, Email: example@example.com
# Requires ssmtp, curl, wget packages; ssmtp as sudoer w/ no password

# Global variables
application="CONCERTO"
date_stamp=$(date +%m-%d-%Y)
log_file="/home/concerto/logs/concerto_status.log"
current_dir="/usr/share/concerto/tmp/cache"
site="http://172.16.204.251"
drive="sda1"
threshold="20"

# Determine the number of directories in current directory
cd "${current_dir}"
num_of_dirs=$(ls -d */ 2>&1 | wc -l) 2>&1

# Header for log file.
echo >> "${log_file}"
date >> "${log_file}"
echo >> "${log_file}"
echo "****************************************************" >> "${log_file}"
echo "* PROD ${application} Status & Maint. Script *" >> "${log_file}"
echo "****************************************************" >> "${log_file}"

# Checking the status of site using http codes.
echo >> "${log_file}"
echo "1.) CHECKING STATUS OF ${application}:" >> "${log_file}"
if wget --spider -S "${site}" 2>&1 | grep -w "200\|301" >> "${log_file}" ; then
    echo "${site} is up" >> "${log_file}"
else
    echo "${site} is down" >> "${log_file}"
fi

# Checking connectivity using curl.
echo >> "${log_file}"
echo "2.) CHECKING CONNECTIVITY TO ${application}:" >> "${log_file}"
curl -s -w 'Lookup time:\t%{time_namelookup}\nConnect time:\t%{time_connect}\nPreXfer time:\t%{time_pretransfer}\nStartXfer time:\t%{time_starttransfer}\nTotal time:\t%{time_total}\n' \
        -o /dev/null "${site}" >> "${log_file}"

# Clear the cache file.
echo >> "${log_file}"
echo "3.) CLEARING THE ${application} CACHE FILES:" >> "${log_file}"
echo "Current directory is: ${current_dir}" >> "${log_file}"
echo "There are currently ${num_of_dirs} directories in the cache." >> "${log_file}"
echo "...removing the cache w/ bundle rake command..." >> "${log_file}"
sudo bundle exec rake tmp:clear >> "${log_file}"
num_of_dirs=$(ls -d */ 2>&1 | wc -l) 2>&1
echo "There are now ${num_of_dirs} directories in the cache." >> "${log_file}"

# Dumping the percentage of used hard dive
echo >> "${log_file}"
echo "4.) CHECKING ${application} DISK SPACE:" >> "${log_file}"
echo "...checking disk space..." >> "${log_file}"
percent_full=$(df -h | grep "${drive}" | xargs | cut -d ' ' -f5 | cut -d "%" -f1)
percent_free=$((100-${percent_full}))
if [ "${percent_full}" -ge "${threshold}" ]; then
        echo "The hard drive is GOOD with ${percent_free}% free space!" >> "${log_file}"
else
        echo "DANGER!!! The hard drive only has ${percent_free}% free space!" >> "${log_file}"
fi
echo >> "${log_file}"
echo "Have a great day!" >> "${log_file}"

# Emailing the log to interested parties
cat "${log_file}" | sudo ssmtp example@example.com

Thanks,
Rob