if failed host 1.2.3.4 port 80 protocol HTTP request / then restart
    if 5 restarts with 5 cycles then timeout

I’m using:

check host DOMAIN.COM with address xxx.xxx.xxx.xxx
    if failed port 80 protocol http with timeout 45 seconds then alert

I know it’s only a slight syntax change, but that fixed it for me. Try it out, if it doesn’t fix it let me know and I’ll plugin your syntax on my box and see what it does. Also, for my nginx block I have more checks that you may want to consider:

check process nginx with pidfile /var/run/nginx.pid
        start program = "/etc/init.d/nginx start"
	stop program  = "/etc/init.d/nginx stop"
        if cpu > 60% for 2 cycles then alert
	if cpu > 80% for 5 cycles then restart
	if totalmem > 200.0 MB for 5 cycles then restart
        if children > 250 then restart
	if loadavg(5min) greater than 10 for 8 cycles then stop

:wq!

check process nginx with pidfile /var/run/nginx.pid
start program = “/etc/init.d/nginx start”
stop program = “/etc/init.d/nginx stop”
if failed host 1.2.3.4 port 80 protocol HTTP request / then restart
if 5 restarts with 5 cycles then timeout

When trying to start:

# /etc/init.d/monit start
Starting Process Monitor (monit): HTTP error: Server returned status 400
‘nginx’ failed protocol test [HTTP] at INET[1.2.3.4:80] via TCP
‘nginx’ trying to restart
‘nginx’ stop: /etc/init.d/nginx
‘nginx’ failed to stop

and kills nginx

wget http://1.2.3.4/ returns:
# wget http://208.113.97.31
–21:31:49– http://1.2.3.4/
Connecting to 1.2.3.4… connected.
HTTP request sent, awaiting response… 302
Location: /UnsupportedBrowser?returnUrl= [following]
–21:31:49– http://1.2.3.4/UnsupportedBrowser?returnUrl=
Connecting to 1.2.3.4:80… connected.
HTTP request sent, awaiting response… 200 OK
Length: unspecified [text/html]
Saving to: `UnsupportedBrowser?returnUrl=.2′

[ ] 1,427 –.-K/s in 0s

21:31:49 (136 MB/s) - `UnsupportedBrowser?returnUrl=.2′ saved [1427]

Maybe something wrong with monit’s http client? Any idea?

ErrorDocument 400 /error/invalidSyntax.html

At work I have monit watching Lighttpd without Varnish in the way, so its block in monitrc is this:

check process lighttpd with pidfile /var/run/lighttpd.pid
start program = "/etc/init.d/lighttpd start"
stop program = "/etc/init.d/lighttpd stop"
if cpu > 60% for 2 cycles then alert
if cpu > 80% for 5 cycles then restart
if totalmem > 200.0 MB for 5 cycles then restart
if children > 250 then restart
if loadavg(5min) greater than 10 for 8 cycles then stop
if failed host 127.0.0.1 port 80
protocol HTTP request /monit_check.php
timeout 20 seconds
then restart
if 3 restarts within 5 cycles then timeout
depends on lighttpd_bin
depends on lighttpd_rc
group system

So, from your server, can you do something like:

wget http://127.0.0.1

and get a successful response? If not, you may want to place a ‘dummy’ file for it to grab (touch /var/www/test.html; chown www-data /var/www/test.html) so it’ll give you a 200 - Success response:

mbglinuxdevsrv01:/etc/monit# wget http://127.0.0.1/test.html
–2008-05-01 10:13:24– http://127.0.0.1/test.html
Connecting to 127.0.0.1:80… connected.
HTTP request sent, awaiting response… 200 OK
[...]

I use a PHP file for monit to check so it can ensure that Fastcgi is still running, since a restart of Lighttpd would restart the Fastcgi process, although I’m going to start running that as a separate process so monit will watch it directly.

Let me know, that should work.

Nice article. However my lighttpd instance only throws a 400 error.
monit[9262]: HTTP error: Server returned status 400

My app server is monitored the exact same way as lighttpd but no error.

check process lighttpd with pidfile /var/run/lighttpd.pid
group root
start program = “/etc/init.d/lighttpd start”
stop program = “/etc/init.d/lighttpd stop”
if failed host 192.168.10.6 port 80 protocol http
then restart
alert XXXX@XXXX with the mail-format { subject: Alarm Webserver is down! }
if 5 restarts within 5 cycles then timeout

Any ideas ?