Nixpoint: March 2017

Wednesday, March 29, 2017

Daily Task Automation: High load notification

The below code will trigger an email if the load is higher than 5

load=`w | head -n1 | awk '{print$10}' | cut -d"," -f1`
if [ $load -gt 5 ]; then
echo "High Load Found." | mail -s "High Load Found."  mail@example.com
fi

Tuesday, March 28, 2017

Ansible - wait_for module

wait_for - Waits for a condition before continuing

EXAMPLES

- name: sleep for 300 seconds and continue with play
wait_for: timeout=300
delegate_to: localhost

- name: Wait 300 seconds for port 8000 to become open on the host, don't start checking for 10 seconds
wait_for:
port: 8000
delay: 10

- name: Wait 300 seconds for port 8000 of any IP to close active connections, don't start checking for 10 seconds
wait_for:
host: 0.0.0.0
port: 8000
delay: 10
state: drained

- name: Wait 300 seconds for port 8000 of any IP to close active connections, ignoring connections for specified hosts
wait_for:
host: 0.0.0.0
port: 8000
state: drained
exclude_hosts: 10.2.1.2,10.2.1.3

- name: Wait until the file /tmp/foo is present before continuing
wait_for:
path: /tmp/foo

- name: Wait until the string "completed" is in the file /tmp/foo before continuing
wait_for:
path: /tmp/foo
search_regex: completed

- name: Wait until the lock file is removed
wait_for:
path: /var/lock/file.lock
state: absent

- name: Wait until the process is finished and pid was destroyed
wait_for:
path: /proc/3466/status
state: absent

- name: Output customized message when failed
wait_for:
path: /tmp/foo
state: present
msg: Timeout to find file /tmp/foo

Monday, March 6, 2017

Monitoring script & html output

Here we are monitoring the file system usage by 'df -h' command and output of this command can be accessible via web browser.

#!/bin/bash
# Sample script to demonstrate the creation of an HTML report using shell scripting
# Web directory
df -h > /var/www/html/test.txt
WEB_DIR=/var/www/html
# A little CSS and table layout to make the report look a little nicer
echo "<HTML>
<HEAD>
<style>
.titulo{font-size: 1em; color: white; background:#0863CE; padding: 0.1em 0.2em;}
table
{
border-collapse:collapse;
}
table, td, th
{
border:1px solid black;
}
</style>
<meta http-equiv='Content-Type' content='text/html; charset=UTF-8' />
</HEAD>
<BODY>" > $WEB_DIR/report.html
# View hostname and insert it at the top of the html body
HOST=$(hostname)
echo "Filesystem usage for host <strong>$HOST</strong><br>
Last updated: <strong>$(date)</strong><br><br>
<table border='1'>
<tr><th class='titulo'>Filesystem</td>
<th class='titulo'>Size</td>
<th class='titulo'>Use %</td>
</tr>" >> $WEB_DIR/report.html
# Read the output of df -h line by line
while read line; do
echo "<tr><td align='center'>" >> $WEB_DIR/report.html
echo $line | awk '{print $1}' >> $WEB_DIR/report.html
echo "</td><td align='center'>" >> $WEB_DIR/report.html
echo $line | awk '{print $2}' >> $WEB_DIR/report.html
echo "</td><td align='center'>" >> $WEB_DIR/report.html
echo $line | awk '{print $5}' >> $WEB_DIR/report.html
echo "</td></tr>" >> $WEB_DIR/report.html
done < /var/www/html/test.txt
echo "</table></BODY></HTML>" >> $WEB_DIR/report.html

Open the report.html file in a web browser. You will see output similar to below.

You can add to that report as much information as you want. To run the script every day at 1:30 pm, add the following crontab entry:

30 13 * * * /root/scripts/filesystem_usage.sh