Scribblings of a Techie
Last Friday, while tracking Debian Testing, the courier package was updated, and while authentication could be seen to be successful, actually using IMAP seemed to fail.
Turns out the FAM package was somehow to blame; installing fam and libfam0 was the solution. This uninstalled gamin for me. So if you’re pulling your hair out with a similar courier/imap issue, then perhaps have a look at the courier-imap mailing list.
It’s taken some time, but now none of my personal Linux hosts (4 in total) are running the 2.6 kernel any more.
From the start (January) my company web host on Amazon EC2 has been running a 3.x kernel. My little Acer Aspire Revo low power home server, with attached disk pack that sits in my shed in a network cabinet has run 3.x for the last 6 months or so. My Linux laptop (Dell Studio 1558) which only recently got installed (and, since removing Windows, hasn’t overheated once!) went to 3.x immediately. And the last piece of the puzzel is a virtual machine I’ve had for many years with Bytemark.co.uk – they’re now offering a 3.2 kernel in their menu of selectable kernels.
Not that 3.x is that much different than 2.6.3x; but its a line in the sand of feature and security thats easy to identify. But with nearly 15 years of looking at a 2.x kernel, its about time we moved to 3.x!
I’ve been running an IPv6 tunnel for a long time, but occasionally I’ve been seeing traffic hang on it. It looks like it was the MTU, defaulting at 1500 bytes, causing issues when large amounts of data were being shuffled OUT from my Linux box, back to the ‘net’.
The fix is easy: /etc/network/interfaces should have an “up” line for the interface definition saying: up ip link set mtu 1280 dev henet, where henet is the name of your tunnel interface.
Easy enough to skip this line if your tunnel appears to be working OK, but interesting to track down.
As many would know, Debian GNU/Linux is one of the oldest, and the largest Linux distributions that is available for free. Since it was first released in 1993, several people have analysed the size and produced cost estimates for the project.
In 2001, Jesús M. González-Barahona et al produced an article entitled “Counting Potatoes“, an analysis of Debian 2.2 (code named Potato). When Potato was released in June 2003, it contained 2,800 source packages of software, totalling around 55 million lines of source code. When using David A. Wheeler’s sloccount tool to apply the COCOMO model of development, and an average developer salary of US$56,000, the projected development cost that González-Barahona calculated to start-from-scratch and build Debian 2.2 in 2003 was US$1.9 billion.
In 2007 an analysis entitled ‘Macro-level software evolution: a case study of a large software compilation‘ by Jesús M. González-Barahona, Gregorio Robles, Martin Michlmayr, Juan José Amor and Daniel M. German was released. It found that Debian 4.0 (codename Etch released April 2007) had just over 10,000 source packages of software and 288 million lines of source code. This analysis also delved into the dependencies of software packages, and the update flow between Debian release (not all packages are updated with each release).
Today (February 2012) the current development version of Debian, codenamed Wheezy, contains some 17,141 source packages of software, but as it’s still in development this number may change over the coming months.
I analysied the source code in Wheezy, looking at the content from the “original” software that Debian distributes from its upstream authors without including the additional patches that Debian Developers apply to this software, or the package management scripts (used to install, configure and de-install packages). One might argue that these patches and configuration scripts are the added value of Debian, however the in my analysis I only examined the ‘pristine’ upstream source code.
By using David A Wheeler’s sloccount tool and average wage of a developer of US$72,533 (using median estimates from Salary.com and PayScale.com for 2011) I summed the individual results to find a total of 419,776,604 source lines of code for the ‘pristine’ upstream sources, in 31 programming languages — including 429 lines of Cobol and 1933 lines of Modula3!
In my analysis the projected cost of producing Debian Wheezy in February 2012 is US$19,070,177,727 (AU$17.7B, EUR€14.4B, GBP£12.11B), making each package’s upstream source code wrth an average of US$1,112,547.56 (AU$837K) to produce. Impressively, this is all free (of cost).
In 2004 David A. Wheeler did a cost analysis of the Linux Kernel project by itself. He found 4,000,000 source lines of code (SLOC), and a projected cost between US$175M and US$611M depending on the complexity rating of the software. Within my analysis above, I used the ‘standard’ (default) complexity with the adjusted salary for 2011 (US$72K), and deducted that Kernel version 3.1.8 with almost 10,000,000 lines of source code would be worth US$540M at standard complexity, or US$1,877M when rated as ‘complex’.
Another Kernel Costing in 2011 put this figure at US$3 billion, so perhaps there’s some more variance in here to play with.
Other highlights by project included:
| Project | Version | Thousands of SLOC |
Projected cost at US$72,533/developer/year |
|---|---|---|---|
| Samba | 3.6.1 | 2,000 | US$101 (AU$93M) |
| Apache | 2.2.9 | 693 | US$33.5M (AU$31M) |
| MySQL | 5.5.17 | 1,200 | US$64.2M (AU$59.7M) |
| Perl | 5.14.2 | 669 | US$32.3M (AU$30M) |
| PHP | 5.3.9 | 693 | US$33.5M (AU$31.1M) |
| Bind | 9.7.3 | 319 | US$14.8M (AU$13.8M) |
| Moodle | 1.9.9 | 396 | US$18.6M (AU$17.3M) |
| Dasher | 4.11 | 109 | US$4.8M (AU$4.4M) |
| DVSwitch | 0.8.3.6 | 6 | US$250K (AU$232K) |
The upstream code that Debian distributes is written in many different languages. ANSI C with 168,536,758 is the dominant language (40% of all lines), followed by C++ at 83,187,329 (20%) and Java with 34,698,990 (8%).
If you are intersted in finding the line count and cost projections for any of the 17,000+ projects, you will find them in the raw data CSV.
Ohcount is another source code cost analysis tool. In March 2011 Ohcount was run across Debian Sid: its results are here. In comparison, its results appear much lower than the sloccount tool. There’s also the Ohloh.net Debian Estimate which only finds 55 Million source lines of code and a projected cost of US$1B. However Ohloh uses Ohcount for its estimates, and seems to be to be around 370 million SLOC missing compared to my recent analysis.
Over the last 10 years the cost to develop Debian has increased ten-fold. It’s intersting to know that US$19 billion of software is available to use, review, extend, and share, for the bargain price of $0. If we were to add in Debian patches and install scripts then this projected figure would increase. If only more organisations would realise the potential they have before them.
Need help with Linux (including Debian), Perl, or AWS? See www.jamesbromberger.com.
I’ve been using Amazon’s Elastic Load Balancing (ELB) service for about a year now, and thought I should pen some of the things I’ve had to do to make it work nicely.
Firstly, when using HTTP with Apache, you probably want to add a new log format that, instead of using the Source IP address of the connection int he first field, you use the extra header that ELB adds, X-Forwarded-For. It’s very simple, something like:
LogFormat "%{X-Forwarded-For}i %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" fwd_combined
… and then wherever you’ve been using a Log statement with format “common”, just use “fwd_common”. Next, if you’re trying to use your domain name as your web server, eg “example.com” instead (or as well) as “www.example.com”, then with Amazon Route53 (DNS hosting) you’ll get a message about a conflict witht he “apex” of the domain. You get around this using the elb-associate-route53-hosted-zone command line tool, with something like:
./elb-associate-route53-hosted-zone ELB-Web --region ap-southeast-1 --hosted-zone-id Z3S76ABCFYXRX6 --rr-name example.com --weight 100
And if you want to also use IPv6:
./elb-associate-route53-hosted-zone ELB-Web --region ap-southeast-1 --hosted-zone-id Z3S76ABCFYXRX6 --rr-name example.com --weight 100 --rr-type AAAA
If you’re using HTTPS, then you may have an issue if you chose to pass your SSL traffic through the ELB (just as a generic TCP stream). Since the content is encrypted, the ELB cannot modify the request header to add the X-Forwarded-For. Your only option is to “terminate” the incoming HTTPS connection on the ELB, and then having it establish a new connection to the back end instance (web server). You will need to load your certificate and key into the ELB for it to correctly represent itself as the target server. This will be an overhead on the load balancer having to decrypt (and option re-encrypt to the back end), so be aware of the costs.
One of the nice things about having the ELB in place, even for a single instance web site, is that it will do health checks and push the results to CloudWatch. CloudWatch will give you pretty graphs, but also permit you to set Alerts, which may be pushed to the Amazon Notification Service – which in turn can send you an email, or call a URL to trigger some other action that you configure (send SMS, or sound a klaxon?).