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T.Dargers: When searching for a monitor solution we wanted a smart and small size solution with minimum administrative overhead.
Monit gives us monitoring for all company services like internal and external web, internal and external mailserver, database servers and communication servers (jabber).
Since then monit works perfectly and quietly in the background just doing it's job. We did not have any failure since but every single administrative task that led to unresponsiveness was instantely reported via email AND via jabber. Monit is one of those - just works - solutions that do not need any attention during the daily work. And believe me, it is a good feeling to know it is there and will tell instantly (via jabber and email) if there is any outage.
Dietmar Labahn: I use Linux CUPS and LPRng Print- and workflow servers. Because these servers are essential to the company (Automotive), I decided to implement a Heartbeat solution. During the print process the invoices are also transfered to a document management system (EASY), we convert the printfiles as well to PDF and create index files for the DMS. In addition, we send certain printfiles to certain people as PDF mail attachments.
It is clear that it would cost the company a lot of money, if the system would fail. I decided to use the HA system in connection with monit. Two Intel-based servers (Raid 5) running under SUSE LINUX 8.2 with mostly redundant hardware is the platform.
Heartbeat and monit are configured as suggested under the monit website, which means that monit is started by the system daemon (configured via inittab). It then starts Heartbeat, via its configuration file monitrc, by the monit option "start group local". This means, when coming up, monit starts all services marked as local. The services CUPS, postfix and Samba are started by Heartbeat, using the monit "Start Group" option. This means that the services are under control of both HA and monit. HA takes care that the services are only running on the active node, and monit takes care that they are monitored and restarted on the active node if needed. Because the main server is changed now and then (printers added, deleted, configuration files changed etc), I use CRON and scripts to update the backup server with all the relevant files once a day (at night).
Until now, it has worked like a charm (even though no failures happened yet). From my point of view, I can recommend it highly. It takes some time to get to all the bits, but then..... On the other hand -- who ever said that such a highly sofisticated system is trivial. I am now at my 4th HA installation, and it works perfectly!
Tim Sturtewagen: I have only last week installed monit on a machine we use for tomcat application serving. Our company is in the process of upgrading the server, but needed a monitoring application for the time being to make sure the tomcat server doesn't go down every week or two. Our ISP (www.positive-internet.com) advised us to try out monit;
"My advice would be to use something like monit. You can install it via Debian (apt-get install monit). It's a wonderful bit of software. ... Spend an hour or so looking at the config examples, and then another setting up your machine just so means that you can get it running like clockwork."
So I did! It took me some more time - I had some calls and other stuff in between - but after a few hours, monit was up and running on Thursday afternoon.
I only installed one configuration, for checking the tomcat process over a http connection. In case of no response, monit would restart the tomcat app server. As alert address I entered my i-mode email address, so that any email would arrive on my mobile phone [I live in Brussels and use www.base.be].
On Friday night I left for Madrid, as I was going to a wedding party on Sunday afternoon [in Madrid I automatically roamed on www.amena.com].
Quiet weekend, nice wheather, cool city and then ... it is Sunday morning. Me and my girlfriend are getting ready to go to the party, we still have one hour before we have to leave. Suddenly an email arrives on my phone. It was monit, telling me the tomcat protocol test had failed.
Damn!
It was 35 degrees outside, and I was sweating like hell. I didn't really have the time to sort out what was happening. There was a computer running in the very room I was in, so I looked up the server, and indeed it was down, showing me the horrible "Internal Server Error". At the same moment a second mail arrived. Monit again. The tomcat4 process had died.
There was no ssh client on the computer I was using, so I quickly downloaded putty. Before I had opened it, a third mail arrived. More bad news from monit, I thought. But no, this was a happy message. My faithful employee was sending me tomcat's new pid id! And another mail came in. Now telling me the tomcat connection had succeeded.
I reloaded the browser window, and yes, all was up again! In only 6 minutes, monit had handled the situation and kindly told me what it was doing in the meantime. Wonderful.
Many thanks and kind regards,
methke01: I was quite nervous, registered for some shops, mailing lists and things like that but never got mails in reply. After 4 days being not reachable and searching for the reason I found a changed library, postfix linked to it and down for nearly a week. I already use a small SVG-perl script to render the system's temperature to my homepage, but that does not show if a certain process fails or is not up and running.
After crawling through gentoo's repository I found the only one package to solve my problems and finally emerged monit. It did not run out of the box, the page was empty and most of the listed examples had to be edited. But within 15 minutes I had a full setup, full service and only green status messages.
Thanks for the small but useful package, Greetings from Germany
Lois Garcia: I am starting my third job as a junior sysadmin and am very determined to leave behind the "junior" in my title forever. Because I have a background in tech writing, and I want to be useful on the job right away, my duties have resembled something like an IT secretary. Not this time! My third week on the job, I took care of an ongoing problem. I set up Nagios monitoring (after two days of frantic effort to find the right plugin) for a proxy machine whose Squid process periodically dies and no one would notice. With Nagios in place, we will know when it dies and can restart the process. But how much nicer would it be if it restarted automatically? With that thought in mind, this morning I started to look for a solution, and monit has already proven itself! It took a little time of careful reading of the man page, plus a look at some of the examples on this website, and that was it! I am very grateful for monit and plan to expand my knowledge of it. This is a tool so useful and elegant that every sysadmin should know about it.