Mac Networking: Shepherd Services with Simple Simon
If you're looking for a service monitoring package, there's no shortage of options. On the Mac side, Dejal's Simon is one you'll want to consider if you're trying to keep an eye on a small set of services.
When it comes to networking, life is all about tradeoffs. If you decide your simple Web site has grown beyond something you want to run under your desk or out of a spare closet, you might want to move to a hosted provider. But once you've got that provider, a lot of things are out of your hands.
For instance, I live in Portland, Ore.,but the company that hosts my Web and mail services is in Los Angeles. I love the service, but when I made the switch from running an old Pentium out of a closet to something running on a rack in California, I lost two key tests for hardware problems: the smell of burning plastic and the sight of blue smoke hanging in the air.
The most basic tools for checking on a server over the 'net usually come free with your computer. A few weeks ago, for instance, I described OS X's Network Utility, which bundles up tools like ping, traceroute and a modest portscanner. They're all fine for checking connectivity, but they aren't particularly good for telling you whether a particular service is even available. If your Web server stopped responding, pinging the host running the server might show you've got a connection to it. That doesn't tell you much about whether the actual Web server software has crashed.
It's not particularly hard to come up with ways to monitor services from afar, and plenty of people have written little apps and scripts to do just that. The basic function all service monitors perform is pretty simple: Try to access a service every so often, log any failures, and optionally notify someone if something isn't working.
Professional admins use complex variations on this theme, getting automated pages or e-mails as soon as a service goes down, any time of day. When we're talking about something less critical, or when "sys admin" is a title we took on because no one else even knew where the server's on switch was, our "notification system" tends to be arriving at the office in the morning and learning that "the internets aren't working" from the receptionist, who's been there since 8 a.m.
Having some kind of monitor in place that's been gathering information and testing services is useful in these cases because we can get a sense of how long a problem's been happening, and if there are any common denominators that might help narrow down the source of the problem.
For instance, if you have one host for your Web site, but another for e-mail, monitors on each might help you narrow problems with them down to one server or the other, or your own Internet connection. Or when you're running a file server and can't seem to connect to it, a properly configured monitor can tell you whether the service itself is broken, or if, perhaps, you just didn't configure a client correctly.
As network services get more complex, even for fairly modest sites, the need for good monitoring grows, too. Consider a dynamic Web site driven by Apache and MySQL that offers up access to some sort of streaming media. Sites like that are common and simple enough that my own hosting provider can have one up and running within ten minutes. Simple as it is to set up, such a site may well depend on three or more different hosts or applications to operate: the Apache server, the database server and a streaming server. Maybe with an authentication service in there as well. It's not hard to imagine a scenario where such a site would go down with little indication of which part of it was failing.
As you can imagine, there are a lot of service monitoring packages out there. Because they're in a class of software that involves something people need more than they really want, they can get a little pricey. On the Mac side, one you'll definitely want to consider if you're just trying to keep an eye on a small set of services, is Dejal's Simon.
Simon has a few things going for it for small networkers:
Simon has another useful feature outside monitoring services: It can check for changes to files or Web pages. While the core functionality of the program is clearly built around network services, Simon doubles as a handy way to keep up with sites that haven't embraced RSS.
The list of services Simon can monitor with its tests covers all the basics:
If that list isn't adequate, you can also use the Port Service Plugin Simon provides to write your own monitor, setting the dialog Simon should try with a given service, and the responses it should expect.
A typical Simon "test" involves describing the kind of service you want to monitor, providing the address or other pertinent details, and setting an interval.
You can also configure the kinds of notifications you get. In addition to the typical e-mail message or simple buzzer, you can perform more complex actions: Simon can launch a specific application, bring up a changed Web page or make an entry in a MySQL database, which offers a lot of flexibility for building your own reports. If you know of an e-mail to SMS gateway (your cellular carrier probably has one), you could set up Simon to text you when something goes wrong.
Simon's other broad area of functionality is found in its reports feature. Reports are customizable in a number of ways, from providing a simple comma-delimited text file to generating an RSS feed. It can also provide clean HTML reports it uploads to a given site, or save to a local file.
The HTML reports are ideal for situations where you deal with a number of users and don't want to lose time answering calls about a service being down when you'd rather be fixing the service: Just put up a notification page somewhere reliable (on a local server if you can manage that, using OS X's built-in Web sharing, for instance) and encourage everyone to bookmark it. Real IT departments might have time to devote to someone patiently notifying everyone of a service outage. Small offices or consultants who deal with far-flung clients don't.
Simon's pricing scheme is simple:
If you have a typical SOHO setup with just a few servers, the Basic license will probably cover you, and maybe leave a few slots open to keep an eye on sites that don't bother to provide RSS. Simon makes it so easy to keep an eye on so many things, though, you might find yourself springing for the Standard license in short order, just because it makes monitoring kind of fun.Add to del.icio.us | DiggThis
For more help, don't forget to try one of our PracticallyNetworked Forums.
|Home | Networking | Backgrounders | Internet Sharing | Security | HowTo | Troubleshooting | Reviews | News | About | Jobs | Tools | Forums|