Automate system administration tasks using Nagios
As a system administrator, one often have to do repetitive tasks such as checking for free disk space, check mail queues and monitor critical services. If there are only a handful of servers, this task may not be very intimidating, but there are many times when there are many servers to monitor, or just for the sake of automation. This is where Nagios comes in.
Nagios is a host and service monitor designed to inform you of network problems before your clients, end-users or managers do.
This is exactly what we need to make an automated system for monitoring! I will not go into details on how to set this up, since there is an excellent quick start guide available on the website. Instead I will focus on how Nagios has eased the burden of managing a large number of servers.
I have ready made templates for servers and when a new server is added, I just create a copy of the template and add or remove the services needed to monitor the server.
Public services are easy to monitor directly from Nagios, but private data such as disk space and CPU load demands a local service running on each of the servers. This is where NRPE comes into play. NRPE is a daemon which listens on the network and will respond to Nagios queries, using standard Nagios plugins. In Debian and Ubuntu, just install the nagios-nrpe-server package, and in Windows NSClient is very usable and easy to configure.
The last thing is alerts management. All servers that someone else manages, or is in charge of, should receive the Nagios alerts for that server. It will dramatically lighten the administration burden if it is possible to delegate as much as the server / service responsibility to other people. For extremely critical services, there should be an SMS gateway, which sends a message to the administrator or someone in charge of the server. This ensures that attention is immediately brought to the problem.
Squirrelfish Javascript engine in Webkit — speeds up Safari
Webkit, the rendering engine in the Safari browser just got a new Javascript engine. They are promising a dramatic increase in speed, and it seems to match up. (the bigger number the better)
SquirrelFish’s bytecode engine elegantly eliminates almost all of the overhead of a tree-walking interpreter. First, a bytecode stream exactly describes the operations needed to execute a program. Compiling to bytecode implicitly strips away irrelevant grammatical structure. Second, a bytecode dispatch is a single direct memory read, followed by a single indirect branch. Therefore, executing a bytecode instruction is much faster than visiting a syntax tree node. Third, with the syntax tree gone, the interpreter no longer needs to propagate execution state between syntax tree nodes. – The webkit blog
If you are running Mac and are using Safari, you can download an updated nightly Webkit build. Now you can try the new version without having to wait for Apple to release an updated version of Safari.
Zen Photo – the zen of photo albums
There are lots of great online photo sharing sites such as Flickr and Zooomr, but it is kind of nice to have the pictures on one’s own server. In the past I have been using Gallery 2, Coppermine and other types of galleries. They are all very competent but lacks one essential thing – simplicity, while being elegant at the same time. This is where Zen Photo comes in.
Zen photo is very simple, stylish and fresh, but it still has all features that one would ever need. Support for themes, comments, spam fighting, RSS feeds and other things are of course supported. There are also plugins available for integration with WordPress, which we all love.
There is one thing that needs to be done though, and that is to somehow make it easy to upload images from the mobile phone to the site. The fastest way would probably be to email everyting to an account and use a script to fetch all images and add them to the site. I will definitely look into that.
Visit my gallery at gallery.chadda.se for a real life demonstration.
Merge your Google talk and MSN Messenger accounts
If you are using Google Chat or any Jabber account, you have probably noticed that you can connect to the same account from multiple places simultaneously. Now image that you could do the same with MSN Messenger – well now you can!
Use Gajim or another Jabber client with transport support and just add an MSN transport at a Jabber server. Just use a public Jabber server with support for MSN transports if you don’t have your own.
Just select the MSN transport and enter your username and password, and your Messenger contact list should start entering the Jabber list. If you now look at the chat in Gmail or another Jabber client such as iChat, all your contacts should be there.
There are some downsides to this setup though. User pictures are not always updated as they should, as well as set usernames.
Co-op, new service from Google
Google has released a new service called Google Co-op where users can create their custom search engine. It of course still uses the Google search, but it enables you to only include certain sites, or put emphasis on them.
There is also the possibility to host the results on you own page, using their web-API. For this demonstration, I am showing the results on their site for simplicity. Here is a search box that only searches this site.
More information can be found on the Google blog.
Firefox 2.0 released
Officially due tomorrow, Firefox 2.0 final has been pushed to the file servers and can already be downloaded. Lots of new features such as a built-in spell checker, nice looking theme, microsummaries, overall speed improvements and lots of other things.
Download it for yourself and give it a try! Windows, Mac, Linux.
WWW is deprecated
There seems to be an unhealthy obsession to prefix all domain names with www, even when there is no apparent need for it. The people behind no-www have a well-put argument why this should be obsoleted as soon as possible.
By default, all popular Web browsers assume the HTTP protocol. In doing so, the software prepends the ‘http://’ onto the requested URL and automatically connect to the HTTP server on port 80. Why then do many servers require their websites to communicate through the www subdomain? Mail servers do not require you to send emails to recipient@mail.domain.com. Likewise, web servers should allow access to their pages though the main domain unless a particular subdomain is required.
There are of course some apparent differences in how mail and the web works, where mail is controlled by DNS MX records and the web only uses standard lookups, but the reasoning is still valid. There are some terrifying examples of prefixed www on subdomains which can be many levels deep.
Dreamhost increasing space and transfer
Dreamhost has just upped their transfer to 2TB and the disk space to 200GB for the standard account. All I can say is thank you!
They have also added the username+tag@host like Gmail has, which is a very nice and useful feature. There is now also a files section where people can upload files and keep them permanently.
Is Newsvine the future of news?
Most traditional news papers and online news websites have a number of writers who contribute to the paper. There is however, a new way of creating online news papers — Letting the readers to the writing. As chaotic it may sound, it works fairly well overall. Sites such as Digg use the same style of editorial control, where users create and moderate stories.
The thing that separates Newsvine from other sites such as Digg, is that it is a replacement for a regular news paper, not just aimed for a niche market. Newsvine is currently in beta, and to use it one has to get an invite. Once you are in, you can choose to go about things in a number of ways.
Perhaps you do not want to contribute and just read the paper? Fine, don’t do that. There is lots of up-to-date content available and just pick your topic from the menu, or just read the top news directly. If you like to contribute, but don’t have any writing skills or are just lazy, there is a concept called seeding. This is a function where users can, when they visit articles on the internet, annotate them and send them to Newsvine. They will pop up next to the regular articles and is a great contribution.
If you do want to contribute to Newsvine, you get your own column as well as the revenues for the adverts on your column! Now, how is that for an inspiration! Great content leads to many reads which leads to money in your pocket.
The real question is now whether this form of editorial control is better than the classic one? If you ask me, it really is. The ability to let everyone contribute leads to a more open society and gives a whole new meaning to free speech.
Correct usage of hyperlinks
They are everywhere! Just click around the web for a couple of seconds, and surely, they will appear.
These hyperlinks embedded in HTML text are beautiful things, but they should be used correctly. This means that links should be integrated in the flowing text, and not appended at the end. An example of this can be found in the last sentence of a recent post at The register.
Pricing and feature options are available for PGP’s web site here and summary in the press release here.
See the problem? The hyperlinks are just named “here”, and neither of them contain a title. If all hyperlinks should be collected and viewed separately, there would be no way to distinguish these two links without looking at the URL itself. The sentence could be written in a much better way, and an example follows.
The pricing and feature options are available at PGP’s web site, as well as a summary of the press release.
See, this makes it far more comprehensible and will aid disabled user’s ability to browse the web without much hassle.