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Chris Dennis: Website version control with Git

Planet HantsLUG - Sat, 26/07/2014 - 21:59

Some notes on using git to manage development and production versions of a website on a Linux server, based on Using Git to manage a web site.  There seem to be several web pages with similar ideas out there: I don’t know who wrote it down first.  And also with reference to Version Control with Git by Jon Lodger.

I’ve adapted those ideas for the way I like to do things:

  • I SSH in to the server, and do the editing there, using vim.
  • I have separate domains for development and production versions of my sites.  For the purposes of these notes, they’re called dev.example.org and www.example.org.  So the development version is also an active real-world website: my nginx configuration makes it only visible to me.
  • The document roots are /var/www/website and /var/www/website-dev respectively.
  • The ‘bare’ production git repository can be anywhere on the server.  I’ll put it at /var/www/website.git.  It’s a git convention to use the .git extension for bare repositories.

The steps for setting it up are as follows.  I’ll leave the setting of suitable permissions and use of sudo as an exercise for the reader.

  1. Put some web pages in /var/www/website-dev.
  2. mkdir /var/www/website cd /var/www/website-dev git init git add <all the appropriate files and directories> git commit -a -m "a message" mkdir /var/www/website.git cd /var/www/website.git git --bare init
  3. Create /var/www/website.git/hooks/post-receive containing:
#!/bin/bash GIT_WORK_TREE=/var/www/website git checkout -f
  • In the following, I’ve used ‘live’ as an alias for the production environment; you could use ‘prod’ or whatever you fancy.
  • chmod +x /var/www/website.git/hoots/post-receive cd /var/www/website-dev git remote add live file:///var/www/website.git git push live +master:refs/heads/master git push --set-upstream live master git push live
  • And, as if by magic, the files from the master branch of /var/www/website-dev are now in /var/www/website.
  • Then whenever you’ve got new code ready to into production, all that’s required is:
  • git push live
    Categories: LUG Community Blogs

    Steve Kemp: The selfish programmer

    Planet HantsLUG - Fri, 25/07/2014 - 14:16

    Once upon a time I wrote a piece of software for scheduling the classes available to a college.

    There was a bug in the scheduler: Students who happened to be named 'Steve Kemp' had a significantly higher chance (>=80% IIRC) of being placed in lessons where the class makeup was more than 50% female.

    This bug was never fixed. Which was nice, because I spent several hours both implementing and disguising this feature.

    I'm was a bad coder when I was a teenager.

    These days I'm still a bad coder, but in different ways.

    Categories: LUG Community Blogs

    The department of dirty

    Planet SurreyLUG - Thu, 24/07/2014 - 10:03

    I quite like the Open Rights Group‘s new campaign against internet filtering

    The Department of Dirty is working with internet and mobile companies to stop the dirty internet. We are committed to protecting children and adults from online filth such as:

    • Talk to Frank: This government website tries to educate young people about drugs. We all know what ‘education’ means, don’t we? Blocked by Three.
    • Girl Guides Essex: They say, ‘guiding is about acquiring skills for life’. We say, why would young girls need skills? Blocked by BT.
    • South London Refugee Association: This charity aims to relieve poverty and distress. Not on our watch they don’t. Blocked by BT, EE, Sky and VirginMedia
    We need you to help us take a stand against blogs, charities and education websites, all of which are being blocked [1]. It’s time to stop this sick filth. Together, we can clean up the internet.www.departmentofdirty.co.uk
    Categories: LUG Community Blogs

    Anton Piatek: The department of dirty

    Planet HantsLUG - Thu, 24/07/2014 - 10:03

    I quite like the Open Rights Group‘s new campaign against internet filtering

    The Department of Dirty is working with internet and mobile companies to stop the dirty internet. We are committed to protecting children and adults from online filth such as:

    • Talk to Frank: This government website tries to educate young people about drugs. We all know what ‘education’ means, don’t we? Blocked by Three.
    • Girl Guides Essex: They say, ‘guiding is about acquiring skills for life’. We say, why would young girls need skills? Blocked by BT.
    • South London Refugee Association: This charity aims to relieve poverty and distress. Not on our watch they don’t. Blocked by BT, EE, Sky and VirginMedia
    We need you to help us take a stand against blogs, charities and education websites, all of which are being blocked [1]. It’s time to stop this sick filth. Together, we can clean up the internet.www.departmentofdirty.co.uk
    Categories: LUG Community Blogs

    Mick Morgan: department of dirty

    Planet ALUG - Wed, 23/07/2014 - 13:42

    Like most ‘net users I get my fair share of spam. Most of it gets binned automatically by my email system, but of course some still gets through so I am used to hitting the delete button on random email from .ru domains offering me the opportunity to “impress my girl tonight”.

    Most such phishing email relies on the recipient being dumb enough, naive enough, or (possibly) drunk enough to actually click through the link to the malicious website. I was therefore more than a little astonished at an email I received today from the open rights group. That email is given below in its entirety (I have obfuscated my email address for obvious reasons).

    From: Department of Dirty
    To: xxxxxxxx@yyy.zzz
    Subject: Cleaning up the Internet
    Date: Wed, 23 Jul 2014 07:14:18 -0400 (EDT)

    Dear Mick,

    Ever thought the internet was just too big? Want to help clean up online filth?

    *Welcome to the Department of Dirty*

    Watch the Department tackling its work here: www.departmentofdirty.co.uk and share our success, as we stop one man try to get one over us with his ‘spotted dick recipe’:

    Department of Dirty Video: http://www.departmentofdirty.co.uk/

    The Department of Dirty is working with internet and mobile companies to stop the dirty internet. We are committed to protecting children and adults from online filth such as:

    *Talk to Frank: This government website tries to educate young people about drugs. We all know what ‘education’ means, don’t we? Blocked by Three.
    *Girl Guides Essex:
    They say, ‘guiding is about acquiring skills for life’. We say, why would young girls need skills? Blocked by BT.
    *South London Refugee Association:
    This charity aims to relieve poverty and distress. Not on our watch they don’t. Blocked by BT, EE, Sky and VirginMedia

    This is just the tip of the iceberg.

    We need you to help us take a stand against blogs, charities and education websites, all of which are being blocked [1]. It’s time to stop this sick filth. Together, we can clean up the internet.

    http://www.departmentofdirty.co.uk

    Sincerely,

    Your Department of Dirty representative

    [1] You can find out what we’re blocking at this convenient website: https://www.blocked.org.uk/

    [DISCLAIMER] This email has come from the Open Rights Group. This email was delivered to: xxxxxxxx@yyy.zzz If you wish to opt out of future emails, you can do so here.

    Now, I’m an ORG supporter (i.e. I am a paying member) and I am sure that someone, somewhere in ORG thought that this email campaign was a great idea. After all, it follows up the ORG’s earlier research on the fairly obvious stupidities arising from the implementation of Dave’s anti-porn campaign, it looks “ironic”, and it uses a snappy domain name which has shades of Monty Python about it. But I’m sorry, in my view this most certainly is not a good idea and I’m sure that ORG will come to regret it.

    One of the most fundamental pieces of advice any and every ‘net user is beaten up with is “do not click on links in unsolicited emails”. In particular, the advice normally goes on – “if that email is from an unknown source, or has in any way a supicious from address you should immediately bin it”.

    This email comes from an unknown address with a wonderfully prurient domain name. Even if it is successful and gets to the intended email inbox [1], it then relies on the recipient breaking a fundamental security rule. It does this by encouraging him (this looks to be male targeted) to click on a link which the naive might believe leads to a porn video.

    How exactly is that going to help?

    ([1] Note. It got to my email inbox because the email system at e-activist.com which sent it is allowed by my filters.)

    Categories: LUG Community Blogs

    MJ Ray: Three systems

    Planet ALUG - Tue, 22/07/2014 - 04:59

    There are three basic systems:

    The first is slick and easy to use, but fiddly to set up correctly and if you want to do something that its makers don’t want you to, it’s rather difficult. If it breaks, then fixing it is also fiddly, if not impossible and requiring complete reinitialisation.

    The second system is an older approach, tried and tested, but fell out of fashion with the rise of the first and very rarely comes preinstalled on new machines. Many recent installations can be switched to and from the first system at the flick of a switch if wanted. It needs a bit more thought to operate but not much and it’s still pretty obvious and intuitive. You can do all sorts of customisations and it’s usually safe to mix and match parts. It’s debatable whether it is more efficient than the first or not.

    The third system is a similar approach to the other two, but simplified in some ways and all the ugly parts are hidden away inside neat packaging. These days you can maintain and customise it yourself without much more difficulty than the other systems, but the basic hardware still attracts a price premium. In theory, it’s less efficient than the other types, but in practice it’s easier to maintain so doesn’t lose much efficiency. Some support companies for the other types won’t touch it while others will only work with it.

    So that’s the three types of bicycle gears: indexed, friction and hub. What did you think it was?

    Categories: LUG Community Blogs

    Chris Lamb: Disabling internet for specific processes with libfiu

    Planet ALUG - Mon, 21/07/2014 - 19:26

    My primary usecase is to prevent testsuites and build systems from contacting internet-based services. This, at the very least, introduces an element of non-determinism and malicious code at worst.

    I use Alberto Bertogli's libfiu for this, specifically the fiu-run utility which part of the fiu-utils package on Debian and Ubuntu.

    Here's a contrived example, where I prevent Curl from talking to the internet:

    $ fiu-run -x -c 'enable name=posix/io/net/connect' curl google.com curl: (6) Couldn't resolve host 'google.com'

    ... and here's an example of it detecting two possibly internet-connecting tests:

    $ fiu-run -x -c 'enable name=posix/io/net/connect' ./manage.py text [..] ---------------------------------------------------------------------- Ran 892 tests in 2.495s FAILED (errors=2) Destroying test database for alias 'default'...

    Note that libfiu inherits all the drawbacks of LD_PRELOAD; in particular, we cannot limit the child process that calls setuid binaries such as /bin/ping:

    $ fiu-run -x -c 'enable name=posix/io/net/connect' ping google.com PING google.com (173.194.41.65) 56(84) bytes of data. 64 bytes from lhr08s01.1e100.net (17.194.41.65): icmp_req=1 ttl=57 time=21.7 ms 64 bytes from lhr08s01.1e100.net (17.194.41.65): icmp_req=2 ttl=57 time=18.9 ms [..]

    Whilst it would certainly be more robust and flexible to use iptables—such as allowing localhost and other local socket connections but disabling all others—I gravitate towards this entirely userspace solution as it requires no setup and I can quickly modify it to block other calls on an ad-hoc basis. The list of other "modules" libfiu supports is viewable here.

    Categories: LUG Community Blogs

    Mick Morgan: drip

    Planet ALUG - Mon, 21/07/2014 - 16:23

    I get my domestic ADSL connectivity from the rather excellent people at Andrews and Arnold.

    Here’s why. And this is the original reason I moved to them.

    They also happily take (and similarly reply to) GPG encrypted support questions.

    Good guys. Thoroughly recommended.

    Now can you /really/ see BT doing any of that?

    ‘thought not.

    Categories: LUG Community Blogs

    Steve Kemp: An alternative to devilspie/devilspie2

    Planet HantsLUG - Mon, 21/07/2014 - 15:30

    Recently I was updating my dotfiles, because I wanted to ensure that media-players were "always on top", when launched, as this suits the way I work.

    For many years I've used devilspie to script the placement of new windows, and once I googled a recipe I managed to achieve my aim.

    However during the course of my googling I discovered that devilspie is unmaintained, and has been replaced by something using Lua - something I like.

    I'm surprised I hadn't realized that the project was dead, although I've always hated the configuration syntax it is something that I've used on a constant basis since I found it.

    Unfortunately the replacement, despite using Lua, and despite being functional just didn't seem to gell with me. So I figured "How hard could it be?".

    In the past I've written softare which iterated over all (visible) windows, and obviously I'm no stranger to writing Lua bindings.

    However I did run into a snag. My initial implementation did two things:

    • Find all windows.
    • For each window invoke a lua script-file.

    This worked. This worked well. This worked too well.

    The problem I ran into was that if I wrote something like "Move window 'emacs' to desktop 2" that action would be applied, over and over again. So if I launched emacs, and then manually moved the window to desktop3 it would jump back!

    In short I needed to add a "stop()" function, which would cause further actions against a given window to cease. (By keeping a linked list of windows-to-ignore, and avoiding processing them.)

    The code did work, but it felt wrong to have an ever-growing linked-list of processed windows. So I figured I'd look at the alternative - the original devilspie used libwnck to operate. That library allows you to nominate a callback to be executed every time a new window is created.

    If you apply your magic only on a window-create event - well you don't need to bother caching prior-windows.

    So in conclusion :

    I think my code is better than devilspie2 because it is smaller, simpler, and does things more neatly - for example instead of a function to get geometry and another to set it, I use one. (e.g. "xy()" returns the position of a window, but xy(3,3) sets it.).

    kpie also allows you to run as a one-off job, and using the simple primitives I wrote a file to dump your windows, and their size/placement, which looks like this:

    shelob ~/git/kpie $ ./kpie --single ./samples/dump.lua -- Screen width : 1920 -- Screen height: 1080 .. if ( ( window_title() == "Buddy List" ) and ( window_class() == "Pidgin" ) and ( window_application() == "Pidgin" ) ) then xy(1536,24 ) size(384,1032 ) workspace(2) end if ( ( window_title() == "feeds" ) and ( window_class() == "Pidgin" ) and ( window_application() == "Pidgin" ) ) then xy(1,24 ) size(1536,1032 ) workspace(2) end ..

    As you can see that has dumped all my windows, along with their current state. This allows a simple starting-point - Configure your windows the way you want them, then dump them to a script file. Re-run that script file and your windows will be set back the way they were! (Obviously there might be tweaks required.)

    I used that starting-point to define a simple recipe for configuring pidgin, which is more flexible than what I ever had with pidgin, and suits my tastes.

    Bug-reports welcome.

    Categories: LUG Community Blogs

    Meeting at "The Moon Under Water"

    Wolverhampton LUG News - Mon, 21/07/2014 - 15:20
    Event-Date: Wednesday, 23 July, 2014 - 19:30 to 23:00Body: 53-55 Lichfield St Wolverhampton West Midlands WV1 1EQ Eat, Drink and talk Linux
    Categories: LUG Community Blogs

    Steve Kemp: Did you know xine will download and execute scripts?

    Planet HantsLUG - Sat, 19/07/2014 - 21:48

    Today I was poking around the source of Xine, the well-known media player. During the course of this poking I spotted that Xine has skin support - something I've been blissfully ignorant of for many years.

    How do these skins work? You bring up the skin-browser, by default this is achieved by pressing "Ctrl-d". The browser will show you previews of the skins available, and allow you to install them.

    How does Xine know what skins are available? It downloads the contents of:

    NOTE: This is an insecure URL.

    The downloaded file is a simple XML thing, containing references to both preview-images and download locations.

    For example the theme "Sunset" has the following details:

    • Download link: http://xine.sourceforge.net/skins/Sunset.tar.gz
    • Preview link: http://xine.sourceforge.net/skins/Sunset.png

    if you choose to install the skin the Sunset.tar.gz file is downloaded, via HTTP, extracted, and the shell-script doinst.sh is executed, if present.

    So if you control DNS on your LAN you can execute arbitrary commands if you persuade a victim to download your "corporate xine theme".

    Probably a low-risk attack, but still a surprise.

    Categories: LUG Community Blogs

    Martin Wimpress: Monitorix on Debian

    Planet HantsLUG - Sat, 19/07/2014 - 12:00

    I have a few Debian servers that run at home and on VPSs. I wanted to add some basic systems monitoring to them, but didn't want anything too complicated to look after. I found Monitorix.

    Monitorix is a free, open source, lightweight system monitoring tool designed to monitor as many services and system resources as possible. It has been created to be used under production Linux/UNIX servers, but due to its simplicity and small size can be used on embedded devices as well.

    Install Monitorix

    This install has been tested on Debian Squeeze and Wheezy. First install the dependencies.

    sudo apt-get install rrdtool perl libwww-perl libmailtools-perl \ libmime-lite-perl librrds-perl libdbi-perl libxml-simple-perl \ libhttp-server-simple-perl libconfig-general-perl libio-socket-ssl-perl

    Now Monitorix itself.

    wget -c "http://apt.izzysoft.de/ubuntu/dists/generic/index.php?file=monitorix_3.5.1-izzy1_all.deb" -O monitorix_3.5.1-izzy1_all.deb sudo dpkg -i monitorix_3.5.1-izzy1_all.deb

    At this point Monitorix is installed and running. Point your browser to http://example.org:8080/monitorix/ and enjoy!

    Configuring Monitorix

    Everything in /etc/monitorix/monitorix.conf is comprehensively documented, just get tweaking.

    Each time you update the configuration Monitorix will require a restart.

    sudo service monitorix restart nginx status

    If you run nginx then you'll want to drop the following into /etc/nginx/conf.d/status.conf so that Monitorix can monitor nginx.

    server { listen localhost:80; location /nginx_status { stub_status on; access_log off; allow 127.0.0.1; deny all; } } References
    Categories: LUG Community Blogs
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