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Steve Engledow (stilvoid): All fired up

Planet ALUG - Thu, 21/08/2014 - 23:52

After putting it off for various reasons for at least a couple of years, I've finally switched back from Chromium to Firefox and I'm very glad I did so.

The recent UI change seems to have upset a lot of Firefox users but it was instrumental in prompting my return and I'm sure others will have felt the same; Firefox once again looks and feels like a modern browser.

I have to say also that it feels an imperial bucketload snappier than Chromium too. The exact opposite was one of the reasons I left in the first place.

Good job Firefolk :)

Categories: LUG Community Blogs

Steve Kemp: Updating Debian Administration

Planet HantsLUG - Thu, 21/08/2014 - 09:50

Recently I've been getting annoyed with the Debian Administration website; too often it would be slower than it should be considering the resources behind it.

As a brief recap I have six nodes:

  • 1 x MySQL Database - The only MySQL database I personally manage these days.
  • 4 x Web Nodes.
  • 1 x Misc server.

The misc server is designed to display events. There is a node.js listener which receives UDP messages and stores them in a rotating buffer. The messages might contain things like "User bob logged in", "Slaughter ran", etc. It's a neat hack which gives a good feeling of what is going on cluster-wide.

I need to rationalize that code - but there's a very simple predecessor posted on github for the curious.

Anyway enough diversions, the database is tuned, and "small". The misc server is almost entirely irrelevent, non-public, and not explicitly advertised.

So what do the web nodes run? Well they run a lot. Potentially.

Each web node has four services configured:

  • Apache 2.x - All nodes.
  • uCarp - All nodes.
  • Pound - Master node.
  • Varnish - Master node.

Apache runs the main site, listening on *:8080.

One of the nodes will be special and will claim a virtual IP provided via ucarp. The virtual IP is actually the end-point visitors hit, meaning we have:

Master HostOther hosts

Running:

  • Apache.
  • Pound.
  • Varnish

Running:

  • Apache.

Pound is configured to listen on the virtual IP and perform SSL termination. That means that incoming requests get proxied from "vip:443 -> vip:80". Varnish listens on "vip:80" and proxies to the back-end apache instances.

The end result should be high availability. In the typical case all four servers are alive, and all is well.

If one server dies, and it is not the master, then it will simply be dropped as a valid back-end. If a single server dies and it is the master then a new one will appear, thanks to the magic of ucarp, and the remaining three will be used as expected.

I'm sure there is a pathological case when all four hosts die, and at that point the site will be down, but that's something that should be atypical.

Yes, I am prone to over-engineering. The site doesn't have any availability requirements that justify this setup, but it is good to experiment and learn things.

So, with this setup in mind, with incoming requests (on average) being divided at random onto one of four hosts, why is the damn thing so slow?

We'll come back to that in the next post.

(Good news though; I fixed it ;)

Categories: LUG Community Blogs

Meeting at "The Moon Under Water"

Wolverhampton LUG News - Mon, 18/08/2014 - 10:50
Event-Date: Wednesday, 20 August, 2014 - 19:30 to 23:00Body: 53-55 Lichfield St Wolverhampton West Midlands WV1 1EQ Eat, Drink and talk Linux
Categories: LUG Community Blogs

Adam Trickett: Bog Roll: Using Less

Planet HantsLUG - Sat, 16/08/2014 - 12:36

Since we moved into our current house we have continually aimed to reduce our gas and electricity use year on year. We started with a number of behaviour changes relative to the previous owners - which saved 50% on gas an electricity on the first year. Since then we have gradually replaced old/worn out/inefficient things with modern/highest efficiency replacements/alternatives and significantly improved the insulation in the loft space and under the ground floor.

Year kWh Total Electricity Gas kWh·m-2 2009 5 000 22 000 233 2010 3 000 19 000 188 2011 2 675 13 945 137.4 2012 3 526 9 606 108.5 2013 2 391 9 402 97.5 2014 1 295 3 749 41.7

The 2009 and 2010 years are estimated and 2010 contains both our and the previous owners usage. 2014 contains only 61% of the year, so isn't comparable yet. I could also do with a scaling factor for the weather as some winters are radically different from others and that makes a big difference to the winter gas figure.

Even though the 2009 figure is an esitmate it's still only about two thirds the EPC survey the house came with when we bought it of E/48 - 314 kWh·m-2, and we're already loads better the best estimate of D/55 - 275 kWh·m-2.

Categories: LUG Community Blogs

Debian Bits: Debian turns 21!

Planet HantsLUG - Sat, 16/08/2014 - 10:45

Today is Debian's 21st anniversary. Plenty of cities are celebrating Debian Day. If you are not close to any of those cities, there's still time for you to organize a little celebration!

Happy 21st birthday Debian!

Categories: LUG Community Blogs

Steve Kemp: A tale of two products

Planet HantsLUG - Fri, 15/08/2014 - 13:14

This is a random post inspired by recent purchases. Some things we buy are practical, others are a little arbitrary.

I tend to avoid buying things for the sake of it, and have explicitly started decluttering our house over the past few years. That said sometimes things just seem sufficiently "cool" that they get bought without too much thought.

This entry is about two things.

A couple of years ago my bathroom was ripped apart and refitted. Gone was the old and nasty room, and in its place was a glorious space. There was only one downside to the new bathroom - you turn on the light and the fan comes on too.

When your wife works funny shifts at the hospital you can find that the (quiet) fan sounds very loud in the middle of the night and wakes you up..

So I figured we could buy a couple of LED lights and scatter them around the place - when it is dark the movement sensors turn on the lights.

These things are amazing. We have one sat on a shelf, one velcroed to the bottom of the sink, and one on the floor, just hidden underneath the toilet.

Due to the shiny-white walls of the room they're all you need in the dark.

By contrast my second purchase was a mistake - The Logitech Harmony 650 Universal Remote Control should be great. It clearly has the features I want - Able to power:

  • Our TV.
  • Our Sky-box.
  • OUr DVD player.

The problem is solely due to the horrific software. You program the device via an application/website which works only under Windows.

I had to resort to installing Windows in a virtual machine to make it run:

# Get the Bus/ID for the USB device bus=$(lsusb |grep -i Harmony | awk '{print $2}' | tr -d 0) id=$(lsusb |grep -i Harmony | awk '{print $4}' | tr -d 0:) # pass to kvm kvm -localtime .. -usb -device usb-host,hostbus=$bus,hostaddr=$id ..

That allows the device to be passed through to windows, though you'll later have to jump onto the Qemu console to re-add the device as the software disconnects and reconnects it at random times, and the bus changes. Sigh.

I guess I can pretend it works, and has cut down on the number of remotes sat on our table, but .. The overwhelmingly negative setup and configuration process has really soured me on it.

There is a linux application which will take a configuration file and squirt it onto the device, when attached via a USB cable. This software, which I found during research prior to buying it, is useful but not as much as I'd expected. Why? Well the software lets you upload the config file, but to get a config file you must fully complete the setup on Windows. It is impossible to configure/use this device solely using GNU/Linux.

(Apparently there is MacOS software too, I don't use macs. *shrugs*)

In conclusion - Motion-activated LED lights, more useful than expected, but Harmony causes Discord.

Categories: LUG Community Blogs

Mick Morgan: net neutrality

Planet ALUG - Wed, 13/08/2014 - 21:46

My apologies that this is a few weeks late – but it still bears posting. John Oliver at HBO gave the best description of the net neutrality argument I have seen so far.

Following that broadcast, the FCC servers were, rather predictably, overwhelmed by the outraged response from the trolls that Oliver set loose.

Unfortunately, as John Naughton reports in the Observer, the FCC are unlikely to be moved by that.

Categories: LUG Community Blogs

Mick Morgan: levison on dime

Planet ALUG - Mon, 11/08/2014 - 20:14

Ladar Levison and Stephen Wyatt presented the upcoming Dark Internet Mail Environment (DIME) at Defcon22 this week. According to El Reg, Levison, who shut down Lavabit, his previous mail service rather than comply with FBI demands that he divulge the private SSL certificates used to encrypt traffic on that service, said:

“I’m not upset that I got railroaded and I had to shut down my business … I’m upset because we need a mil-spec cryptographic mail system for the entire planet just to be able to talk to our friends and family without any kind of fear of government surveillance”.

I think that puts the problem into perspective.

Categories: LUG Community Blogs
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