Git has gotten a lot of hype recently, especially among smaller development teams and contractors, for its flexible, distributed environment, ease of use and while Subversion is the old kid on the block, there are pros and cons for each. This article assumes that you already know the intrinsics of the different version control systems and you’ve decided that Git is for you.

Gitolite is a package that allows us to host our repositories using one dedicated user that has restricted access to the host OS and provides access to the source code.

The following steps helped me successfully install and setup Git on a Ubuntu Server 11.04, install gitolite to host my Git repositories and allow secure access over SSH. I’ve not tested other Linux versions, but assume it should be very similar.

The basic steps include:

• Create User
• Generate SSH keys
• Install Git
• Install Gitolite
• Administer Gitolite

Create Git user on the server

# sudo adduser gituser (enter password when prompted)

Generate SSH RSA keys

On the workstation where you develop and will need access the Git repository, generate a key pair that will be used for authentication. Once generated, we’ll add the public key to the server’s authorized key list file. Ensure that the directory .ssh exists.

# ssh-keygen -t rsa (do not use sudo, specify name as gituser)
# scp .ssh/gituser.pub gituser@hostname:.ssh/

Install Git

You should now be able to login to the server using the certificate and not have to supply a password. Let’s login and proceed with the Git installation.

# ssh gituser@hostname

# su
# apt-get install gettext
# wget http://ftp.de.debian.org/debian/pool/main/g/git/git_1.7.2.5.orig.tar.gz
# tar xzvf git_1.7.2.5.orig.tar.gz
# cd git-1.7.2.5/
# ./configure
# make
# make install

Install Gitolite

Now that we have Git installed, we can use it to get the latest source code of Gitolite. During the checkout, the console output should resemble closely to what’s displayed below.

# su - gituser
# git clone git://github.com/sitaramc/gitolite gitolite-source

Cloning into gitolite-source...
remote: Counting objects: 5425, done.
remote: Compressing objects: 100% (2180/2180), done.
remote: Total 5425 (delta 3812), reused 4762 (delta 3192)
Receiving objects: 100% (5425/5425), 2.01 MiB | 947 KiB/s, done.
Resolving deltas: 100% (3812/3812), done.

Next we run the Gitolite install script. It’ll among other things create two new folders as you can see in the output.

# gitolite-source/src/gl-system-install

The Gitolite install script relies on the path to gl-setup, so we need to add it. The easiest way is to add this line to the .bashrc file in your home directory.

PATH=/home/gituser/bin:$PATH

With the path set, we can now finish the installation.

# gl-setup ~/.ssh/gituser.pub

If everything went as planned, you should see a similar output as below.

The default settings in the rc file (/home/gituser/.gitolite.rc) are fine for most
people but if you wish to make any changes, you can do so now.

hit enter...
creating gitolite-admin...
Initialized empty Git repository in /home/gituser/repositories/gitolite-admin.git/
creating testing...
Initialized empty Git repository in /home/gituser/repositories/testing.git/
[master (root-commit) 4c9dbe8] start
 2 files changed, 6 insertions(+), 0 deletions(-)
 create mode 100644 conf/gitolite.conf
 create mode 100644 keydir/gituser.pub

Finally remove the public key file.

# rm -f gituser.pub

Administer Gitolite

Gitolite is administered by getting a clone of it’s configuration file from the client, modify it and pushing it to the server. This is how we add users, set permissions and create repositories.

#  git clone gituser@hostname:gitolite-admin

Linux Foundation director Jim Zemlin, has some advise for Linux world professionals. He was as of late quoted saying, “Linux’s increasing use across industries is building high demand for Linux jobs despite national unemployment stats.

Linux.com reaches millions of Linux professionals from all over the world. By providing a Jobs Board feature on the popular community site, we can bring together employers, recruiters and job seekers to lay the intellectual foundation for tomorrow’s IT industry.”

Current requirement is for 8,000 Linux-based technical jobs. Unix is being replaced by Linux in a fast pace and most of todays devices run on a changed version of Linux kernel from servers, HDTV desktops to supercomputing data centres.

IT Professionals

Linux beginners can get ahead of the pack and acquire wide Linux skills from sources such as the Linux Qualified Institute where there is vendor also as distribution neutrality. For IT employers using Linux distributions, a in reference to employee with a suite of certification from company vendors such as Red Hat or Novell will whisk greater demand than general Linux expertise.

For the ‘self –learner’, there are innumerable online resources that are offered free. An excellent industry supported example is the IBM developerWorks. With more than 70 articles, resources IT pros looking to benefit and build on their Linux skills, the opportunity at hand is unlimited. The platform alone draws over 300,000 visitors a month and you could just imagine the extent of reach possible at hand to mid-level Linux developers.

Developers

The most professional of Linux developers are the ones in most demand because now it is businesses who are seeking to employ masters of the Linux kernel. Today, these industries need Linux qualifieds who have ‘already- done-it’ and would necessarily step in and resolve the IT problem swiftly and efficiently because of their proven track record.
Consequently, listing all projects handled by you such as Solaris-to-Linux carries more weight age than just your Linux certification.

Salaries

Presume it or not, but the latest salary considerations are not startling primed for Linux qualifieds. Despite similar job titles, a Linux IT professional has a considerably higher commercials in comparison to proprietary software colleagues (Windows …) Moreover, the alarming growth curve of open source mobile computing, enterprise applications is exploding the employment scenario for open source professionals.

It looks as if the Penguin is finally poised for ascendency and it is time for all you closet Linux developers to smarten up, clear your cluttered desktops and set to work on your Linux resumes and set the Penguin to waddle amongst your employers. It is probably that at the least the next half decade is for Linux professionals who are early adapters. Now is the time to get the right skill sets, certifications to rule the world with open source mobiles, tablets and what-have-you-on-Linux.

We often get questions like: What is the difference between Apache Worker Threads vs Prefork? Is it bad to have the values the same configuration? Is it bad to have them different?

In this quick article we like to shed some light between the two modules and assess in what given circumstance, certain os and application would call for which solution.

It all goes back to the old NCSA server where Apache 1 grew up in a UNIX environment. It was a multiprocessing server, where each client would be serviced by one server instance. If there were more concurrent clients than server processes, Apache would fork additional server processes to deal with them. Under normal operation, Apache would preserve a pool of at hand server processes to deal with incoming requests.

Whereas this scheme works well on *NIX-systems, it’s an inefficient solution on platforms such as Windows, where forking a process is an high priced operation. So making Apache truly cross-platform required another solution. The approach adopted for Apache 2 is to turn the core processing into a pluggable module which can be optimized for diverse environments.

Prefork

The Apache Prefork MPM (multi processing module) is a non-threaded model, basically much like Apache 1.x. The threaded model came with version 2.x. It is a safe option in all cases, and for servers running non-thread-safe software such as PHP, it is the only safe option. For some applications, including a myriad of of those favorite with Apache 1.3 (e.g. simple static pages, CGI scripts), the Apache Prefork MPM may be as good as anything.

Keep in mind that on Linux versions, Prefork is commonly reported to be as fast as Worker. On Solaris, Worker is reported to be much faster than Prefork.

Worker Threads

The Apache Worker MPM is the newer, threaded model, whose advantages include lower memory usage which is imperative on busy servers and much greater scalability than that provided by the Prefork version in particular types of applications.

Both of the stable MPM’s suffer from a limitation that affects extremely busy servers. Whereas HTTP keep-alive is essential to decrease TCP association and network overhead, it ties up a server process or thread whilst the keepalive is active. As a consequence, a extremely busy server may run out of at hand threads. A busy server with the Worker MPM may continue tens of thousands of hits per second, as happens with favorite sites such as Facebook or Twitter).

If you like to read up more on the subject, we highly recommend The Apache Modules Book, some excerpts were taken for this article.

Beat Making can be a great way to earn money and build a career in the music industry. Up to now, you only had a couple of options when it came to selecting a beat maker.

The first was to pay a high price for high priced high end equipment.  The other option was to get affordable software that you could afford, but made beats that sounded like crap.

Here you find all types of software for making hip hop beats with software. Find Hip Hop Beat Making Software that is not only easy to use but free too and will support you find the easiest software to use when you need beat making software.

ACID Xpress

ACID Xpress (windows) is probably to most powerful of all free beat making software. It features a killer user interface and automatically increases or decreases tempo and pitch in order to ensure the best beats. A free download is available, simply register for free with Acid Planet.

LMMS

LMMS (windows/linux) feels like FL studio but is not even compatible. LMMS enables you to create beats, compose songs and master mix your entire track. Free beat making software like LMMS are hard to find gems. Download it for fee from sourceforge.

Ardour

Ardour (linux/mac) is a digital audio workstation. You can use it to record audio, edit and blend multi-track audio recordings,  produce your own CDs, blend video soundtracks, or just test out new music and sound ideas. Ardour supports non-destructive, non-linear editing with unlimited undos, 32 bit floating point audio path, unlimited audio tracks and buses and anything-to-anywhere signal routing.

Quartz Studio

Quartz Studio (windows) will certainly please DJs with its myriad of features like “direct to disk” format for recording sixteen individual tracks, editing and synchronization to other music formats and much more. The program as well includes, 4+2 audio tracks, real-time processing effects (Reverb et Chorus) on each track, along with volume and pan, audio track data editing functions, a spacialization interface and Skin difference.

Koblo

Koblo (mac/windows) is an extremely new open source player on the block. Besides audio recording and music making, Koblo has some unusual online collaboration features, as it’s connected to the Koblo cloud and therefore you’ll be able to work online with other musicians or band members.

Rosegarden

Rosegarden (linux) is a well-rounded audio and MIDI sequencer, score editor, and general-purpose music composition and sound editing environment and is an intuitive, attractive application that runs on Linux, ideal for composers, musicians, music students, and small studio or home recording environments. Rosegarden has just introduced the Glasgow Pitch Tracker and it as well supports synthesizers and some plugins unlike a myriad of other free beat making software titles.

April and October are the months where Canonical releases new versions of their OS Ubuntu. And that means it’s time for a new Ubuntu release now, with what may be a ground-breaking user interface and major changes from previous versions that come together nicely.

Ubuntu code named Natty Narwhal, or version 11.04 is here and sporting some radical changes from previous editions of the Linux distro. The most distinguished being the arrival of the Unity desktop environment, which was previously relegated to netbooks. It has integrated search, a combination of launcher and a taskbar, and app menus that have been moved to the top of the screen much like in Max OS X, effectively implementing the best ideas from Apple and Microsoft and a new design.

The new User Interface is not excluding its detractors and reportedly has some stability issues, but you can choose “Ubuntu Classic” at login to stick with Gnome. The update as well makes Firefox 4 the default browser and replaces the Rhythmbox music manager with the sleeker and more functional Banshee Player.

The OS does recognize the iPhone, as we were able to plug in an iPhone 4, import pictures, and work with files and folders on the device, play songs downloaded from iTunes to the iPhone that were purchased with play-anywhere rights.

The 700MB sized ISO image is available for download and still provides the live CD so you can try out the OS without installing anything.

With the release of Firefox version 4 last week, we thought it’s time for a fresh list of most powerful Firefox extensions for web developers. Even though couple of our mentions are not yet compatible with this latest release, we’re convinced they’ll be available in no time.

While release 4 also includes some HTML 5 enhancements, we like to see some new extensions to help developers with canvas, forms, local storage and other new features in the future.

In case, we mean just in case you don’t have Firefox yet, you can get it here.

FireBug

Javascript debugger, live DOM & CSS inspector and so much more. The de-facto single greatest web developer add-on for Firefox.

Web Developer Toolbar

Another great developer tool and addition to FireBug, adds a toolbar with powerful web developer tools at your fingertips.

Live HTTP Headers

As you browse, view live HTTP headers of any page loading in real time.

ColorZilla

An advanced eyedropper, color picker, page zoomer and various colorful goodies.

Cache Status

Easily check cache status and management from the status bar.

Edit Cookies

Edit browser cookies inside Firefox. (As of this writing, not yet compatible with Firefox 4)

Fasterfox

Test, record and improve performance and network tweaks for Firefox.

RefSpoof

Allows for easy spoofing of the HTTP referrer header.

Regular Expressions Tester

Great testing tool for regular expressions validation with colour highlighting.

User Agent Switcher

Adds a menu and toolbar button to easily switch the user agent of the browser.

Show MyIP

Simple but useful, display your current external IP address.

Digest Authentication

Basic http authentication in Apache (mod_auith) has been available for a while, but one major downside still exists, which is the exchange of plain text user name and password information over a possibly unsecured network.
That is where Apache Digest Authentication takes over and provides us with MD5 encrypted values, using the mod_digest apache module.

Here are the steps to create a password file to store all account information, install the apache module mod_auth_digest and the necessary configuration parameters to enable security of our restricted area.

Create Account file

For digest authentication we need to use a utility called htdigest, unlike with basic authentication where we used htpasswd. The application takes the file name, realm and username as arguments, then prompts twice for the user’s password. The flag -c creates a new file, it overrides the existing one if exists.

# sudo htdigest -c /path/to/user/file realm username

Install Module mod_auth_digest

Installing mod_auth_digest on Ubuntu is as easy as calling:

# sudo a2enmod auth_digest

On other systems, you might have to compile apache with the –enable-mod-digest flag.

Configure Virtual Host

Finally, we add the necessary directives to the virtual host configuration, inside the directory section to be more precisely.

<Directory /var/www/website.com>
  AuthType Digest
  AuthName "Restricted Access"
  AuthDigestProvider file
  AuthUserFile /var/.htpass
  AuthGroupFile /dev/null
  AuthDigestDomain /
  Require valid-user
</Directory>

Restart apache and verify your configuration. If you encounter login problems, check the apache error log. A common mistake is to have a mismatch between the “realm” when creating the user file with htdigest and the “AuthName” in the apache config file. These two values need to match.

Sharing files between VM’s can be a pain, especially if your VM is running on a text based server without UI. For example, I start up a new VM for almost anything and I deal with up to 20 different sites and application and every one has it’s own VM.

VMWare provides it’s “Guest Additions” and that includes folder sharing. It works fine on desktop os’s, but on the command line we have to mount it using VMWare’s file system, which can be a bit cumbersome. A much simpler and easier way to share files is via USB or DropBox. Getting the DropBox sync daemon to run is really easy and once running, anything you add to DropBox will be synced to your VM transparently and at network speed.

If you don’t already have a DropBox account setup, get a free one here. Now on to the steps to get the sync daemon up and running.

Steps:

SSH to your Linux server and change to your home directory.
cd ~
for 32-bit os:
wget -O dropbox.tar.gz “http://www.dropbox.com/download/?plat=lnx.x86″
for 64-bit os:
wget -O dropbox.tar.gz “http://www.dropbox.com/download/?plat=lnx.x86_64″
After the file “dropbox.tar.gz” downloaded properly, then extract it
tar -xvzf dropbox.tar.gz
Run dropboxd
~/.dropbox-dist/dropboxd
The following error message is expected: This client is not linked to any account…
Please visit https://www.dropbox.com/cli_link?host_id=123456789qwertyuiop to link this machine.

Copy / paste this url into the browser of your desktop machine and log in. This is the process of where your VM will be authorized and added to the account. Once completed, the daemon dropboxd should have created a ~/Dropbox folder and synchronize your files.

Note:

If you want to change the account it is linked to, unlink it from the first account, then kill the running dropbox process, start it up again (with “~/.dropbox-dist/dropboxd &”) and obtain the new host_id with dbreadconfig.py . If you don’t restart the dropbox client, it will give the same host_id (which for some reason cause me to be unable to change the account it is linked to).

Moving, cloning and modifying Virtual Machines and their associated Virtual Hard Disks in VirtualBox has been no easy task and to make matters worse, are poorly documented at best. In this guide, we’re using VirtualBox 3.2.10 r66523 running on Ubuntu 10.10 64bit host operation system.

Merge Snapshots

Merge all snapshots that we want to be included, delete the ones we don’t want. Unless we do this, we only get the base version and loose all changes contained in those snapshots.

Run VBoxManage

Using VBoxManage clonevdi to copy the virtual hard disk to a new VDI file. The basic syntax is: VBoxManage fullPathTooldVdiFile fullPathTonewVdiFile. We need to ensure that a hard disk with that name does not already exist, otherwise we’ll get errors.
VBoxManage clonevdi /data/VirtualMachines/Windows7.vdi /data/VirtualMachines/Windows7_clone.vdi

Add Disk To Virtual Media Manager

We’ll add the new created hard disk to the Virtual Media Manager. This step ensures that the hard disk has been properly cloned, has the proper permissions and that there are no conflicts with other disks and virtual machines. In VirtualBox, select File -> Virtual Media Manager -> Add and select the cloned file, in our case Windows7_clone.vdi. If there are no errors, we should now see the hard disk listed among the others and are ready to proceed with the new Virtual Machine.

Create new Virtual Machine

In VirtualBox, select Machine -> New  and proceed with the steps to create a new Virtual Machine. At the point we we select a hard disk, click existing and select our new disk.
Start up the new Virtual Machine and change hostname in /etc/hostname and eventually the network configuration in /etc/network/interfaces.

Growing companies at some point are faced with the increased workload to setup, configure and maintain their servers and applications. Administrators try to script repetitive tasks and ultimately look for solutions that are scalable and provide a central management tool base. There are several software packages available, commercial and open source ones.

Puppet is probably the most used open source configuration management package available today and more system administrators and software developers are interested in setting it up within their environment. An excellent book about Puppet (Pulling Strings with Puppet) is available and so are numerous online articles and tutorials. However, lots of online resources are just not quite complete and can lead to lots of frustration, especially in the setup and configuration of Puppet.

So here is another step by step tutorial about how to install and setup Puppet to the point where we can run a simple recipe residing on the server (puppetmaster) and execute on the client. For this illustration we’ll install Puppet on Ubuntu 10.10 using a deb package.

Configure Network and DNS

Setting up configure hostnames on server and client is crucial. Since Puppet uses self signed certificates to secure communication, it’s essential that network is setup properly and hostnames are configured with fully qualified domain names.

Let’s open /etc/hosts and add the necessary entries. (note: If you use a DNS server in your network, those setting changes should be made on your DNS server and not the hosts file)

server hosts file (assuming server = 192.168.1.10, client = 192.168.1.20):

127.0.0.1 localhost.localdomain localhost puppet
192.168.1.10 puppet-server01.example.com puppet-server01 puppet
192.168.1.20 puppet-client01.example.com puppet-client01

verify:

# hostname => puppet-server01
# hostname -f => puppet-server01.example.com

client hosts file:

127.0.0.1 puppet-client01.example.com localhost
192.168.1.10 puppet-server01.example.com puppet-server01 puppet

verify:

# hostname => puppet-client01
# hostname -f => puppet-client01.example.com

In addition, you should ensure that no firewall is blocking port 8140, as Puppet is communicating on this port.

Now we’re ready to move on to installing the puppet server.