A utility to email myself if my site is down

Question

I use Ubuntu 16.04 with Nginx and a few WordPress sites. Sometimes I don't visit a site for a long time (>=1 month) and it might be that the site is down.

I'm looking for a small utility that will email my Gmail account, if one of my Nginx-WordPress sites is down (without mentioning a reason).

Approaches considered so far

1. Creating a tool from scratch

1. Creating the whole non-default configuration for my SMTP server.
2. Adding anc configuring DNS recors at the hosting providers DNS management tool.
3. Adding a weekly cron task with curl -l -L on each domain and save it's output into a file.
4. Adding a weekly cron task of say one hour later, to check each file and email myself if the status code isn't 200.

This might seem simple, but is actually quite complex (though not necessarily complicated), and it also might be a bit fragile. A dedicated, communal, maintained utility might be better for me.

2. Third party tools

I don't want to use some grandiose, third-party network-monitoring service like Nagios, Icinga, Zabbix, Shinken, etc, and they all seem an overkill per this particular cause.

3. Postfix add-on

I've already installed Postfix with the internet-site configuration so that tool might utilize Postfix. I just use the Postfix defaults, some default conf I could add on top of internet-site, maybe without adding and configuring DNS records.

A utility which is an interactive program to re-configure Postfix might ease my pain; I wouldn't have to fill my Ubuntu-Nginx-WordPress-Environment installation-script with much SMTP configuration data. Maybe I'll just have to set some DNS records after that, and that's it. Anything that would ease the process this way or another is also an option for me.

4. Handling the spam filter

Even if Gmail would mistakenly move my first email (or the first series of email) to spam, I could put it into a whitelist.

---

My question

Is there a utility I could use to have this behavior?

Answer 1

Best bet is to use a service like uptime robot. Free tier will cover less than 50 sites, pro plan is quite cheap. It'll do a simple ping check or even HTTP status code check

The upshot of this is that you're not adding an additional point of failure (that you can control). You've no longer got to maintain and update a monitoring service

Answer 2

You can use something like this;

> cat email_warning.sh 
#!/bin/bash

#
# email_warning.sh 
#

UP=true
FROM=you@valid.spf
TO=you@gmail.com
MAX=5
URL="https://$(hostname)/"

function doMail {
    S="$1 $(date)"
    F=$(echo $S | perl -p0e 's/[\s\t ]+/_/g;s/^(.{122}).*$/$1/g')
    echo -e "Subject:$S\n\n$S" | sendmail -F $F -f $FROM $TO
}

function doUP {
    curl -s -m $MAX "$URL" > /dev/null
    R=$?;
    if [ "$R" == "0" -a "$UP" == false ] ; then
        UP=true
        doMail "recovered $URL"
    elif [ "$R" != "0" -a "$UP" == true ] ; then 
        UP=false
        doMail "over $MAX s for $URL"
    fi
}

while [ "" == "" ] ; do
    ping -c 2 8.8.8.8 >/dev/null 2>&1
    if [ "$?" == "0" ] ; then
        doUP
    fi
    sleep 60
done

• just run it in tmux/screen/nohup (or use cron and echo $UP > /dev/shm/email_warning.tmp etc)
• the script can be tuned to monitor a local service or a remote one if you also want emails about network and server issues.
• It's also likely desirable to check the service response for other failure modes (like a non-functioning database).
• You don't need your own functioning SMTP server (though sendmail is installed with postfix) for this to work as long as you are not on a home network
• The doMail function is designed to be optimal for Gmail to forward to a phone without data.
• Gmail spam filter will not be an issue if you have a valid SPF in your DNS or just add the email address to your contacts and add a not spam filter.

Answer 3

Try a hack of the script I built below. My example contains 3 well known hosts and 2 non-existent hosts.

pingtest.sh

HOSTLIST='www.google.com www.oracle.com www.facebook.com www.sdfafdsfdsf.com www.uieyafbmndhfjsbxcvn.com'

BAD_HOSTLIST=
for HOST in $HOSTLIST ; do
        echo $HOST
        ping -c 3 -w 5 $HOST || BAD_HOSTLIST="$BAD_HOSTLIST $HOST"
        echo =======================
done

if [ -n "$BAD_HOSTLIST" ] ; then
        echo ___________________________________________
        echo The following hosts failed the ping test:-
        echo $BAD_HOSTLIST | xargs -n 1
        echo $BAD_HOSTLIST | mailx -s 'Hosts that failed the ping test' MyName@gmail.com
fi

If you need to quickly set up a mail forwarder, try this short & easy article on using ssmtp: https://www.cyberciti.biz/tips/linux-use-gmail-as-a-smarthost.html

A quick look at the output of the script is below:

# ./pingtest.sh
www.google.com
PING www.google.com (216.58.200.100) 56(84) bytes of data.
64 bytes from www.google.com (216.58.200.100): icmp_seq=1 ttl=55 time=29.8 ms
64 bytes from www.google.com (216.58.200.100): icmp_seq=2 ttl=55 time=28.4 ms
64 bytes from www.google.com (216.58.200.100): icmp_seq=3 ttl=55 time=30.3 ms

--- www.google.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 28.483/29.577/30.365/0.810 ms
=======================
www.oracle.com
PING e870.dscx.akamaiedge.net (104.116.147.64) 56(84) bytes of data.
64 bytes from www.oracle.com (104.116.147.64): icmp_seq=1 ttl=56 time=29.5 ms
64 bytes from www.oracle.com (104.116.147.64): icmp_seq=2 ttl=56 time=28.3 ms
64 bytes from www.oracle.com (104.116.147.64): icmp_seq=3 ttl=56 time=27.8 ms

--- e870.dscx.akamaiedge.net ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 27.842/28.570/29.503/0.706 ms

=======================
www.facebook.com
PING star-mini.c10r.facebook.com (157.240.8.35) 56(84) bytes of data.
64 bytes from www.facebook.com (157.240.8.35): icmp_seq=1 ttl=53 time=27.8 ms
64 bytes from www.facebook.com (157.240.8.35): icmp_seq=2 ttl=53 time=79.4 ms
64 bytes from www.facebook.com (157.240.8.35): icmp_seq=3 ttl=53 time=79.0 ms

--- star-mini.c10r.facebook.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 27.887/62.130/79.467/24.215 ms
=======================
www.sdfafdsfdsf.com
ping: www.sdfafdsfdsf.com: Name or service not known
=======================
www.uieyafbmndhfjsbxcvn.com
ping: www.uieyafbmndhfjsbxcvn.com: Name or service not known
=======================
___________________________________________
The following hosts failed the ping test:-
www.sdfafdsfdsf.com
www.uieyafbmndhfjsbxcvn.com

Answer 4

If you are not married to email, you can use Pushbullet, which will send you a push notification to your phone using curl. You need to install it on your mobile device.

Then simple have a small bash script which curls your website and if it does not respond, then you send a push notification straight to your phone like this:

curl -u $auth_token: https://api.pushbullet.com/v2/pushes -d type=note -d title="Alert" -d body="$MSG"

where $auth_token is your Pushbullet auth token after you register.