Peter Mac And Associates

Moving from Subversion to Git

I have been using subversion for a number of years and it wasn’t until I had seen and sampled the simplicity and power of git that I decided once and for all to bite the bullet and migrate all my subversion repositories to git.

I’d done the same from cvs to subversion in the early 2000′s and still think the move worked out well with a bit of preparation.

An unfortunate side effect of subversion is that it takes a good bit of effort to set up and manage a new repository so I ended up with two somewhat monolithic repositories…

1. archives
2. projects

The ‘archives ‘ repository contained all old project work and the ‘projects’ one contained relevant or current project work.

The result of this was that each archive had a bundle of sub-folders, each containing a project in its’ own right. Although git can handle the concept of sub-modules it’s not the best way to structure your project. In fact, it was a pretty lazy to structure my subversion projects in the first place but convenience overcame system administrative chores at the time.

This article explains the following:

1. Converting a monolithic subversion repository to a git repository
2. Breaking out the new git repository into a set of discrete repositories.
3. General backup process and scripts to copy the new repositories across to a backup system.

First off, a couple of conventions I keep are…

My server stores a central set of repositories with the name of myproject.git
My workstations work with their local version of repositories called myproject (no .git)
My server exports it’s .git repositories to a backup server using the same .git naming convention.
I have created a git.git user.group on my server to run all git processes. File ownership is given to this user so other users can’t fowl things up at least without thinking about it first.

Step 1 – Migrating to subversion

I store all my git repositories on a server in the directory

/usr/local/share/gitrepos

All of my subversion repositories are stored in

/usr/local/share/svn

Even though each folder is accessible using standard paths and commands, I have to go through the subversion door using the same mechanism I would access it from a remote box, namely http://. Other people may use svn:// if that’s their way of working.

Migration is taken care of with a single command.

An explanation of all the bits follow:

sudo – because I run everything as unprivileged user, sudo gives me the rights i need to create new files and folders.

git svn – this is the git subcommand that manages conversion of subversion repositories.

clone – make a copy of the repositories that I’m pointing at.

https://localhost/repository/projects – I access all my subversion repositories using secure http. This allows me to securely browse the content across the Internet and track things easily using Trac.

Depending on your setup, this parameter will contain the path to your svn repository,however you access it.

–stdlayout option tells git svn that my subversion repository is in the standard layout of trunk/branch/tags directories.

–authors file – this is a file I created by hand containing a list of all the people who committed project material in the past. It’d format is as follows:

-t tags -b branches -T trunk – these values are for completeness and I’m not sure they are necessary given the –stdlayout option, but if you’ve called your branches, tags and trunks anything different, this is how you find it.

Once the command has completed you should find a projects.git folder has been created and navigating into it you will see all your nasty subversion sub-folders which you should have set up as individual repositories in the first place…tut tut!

Step 2 – Breaking out Git into baby gits

The structure of the new git repository is something like this.

The .git folder (you cans see it using ls -a) contains a list of all the git related material such as project history, revisions and tags.
Check you can see your history by typing

The next task is to break the contents of the rather large ‘project’ folder into a git repository per project.
The tool for the job is a combination of the very useful git subtree command and a bit of custom shell scripting specific to this job.

The subtree functionality was written by Avery Pennarun and is hosted by the github site. You can download the git subtree command from the URL http://github.com/apenwarr/git-subtree. Installation instructions are on the same site so I won’t bore you with it here.

Once you have it installed you’re almost ready to roll. The following shell script has comments at the top to explain what it does. Save this to your favourite scripts folder and chmod it so it’s executable (chmod +x git_breakout.sh).

Then cd into the folder you created earlier (in my case /usr/local/share/gitrepository/projects). Run the script and watch the output. Depending on the size of your projects it will take a bit of time to complete; mine took about 20 minutes.

Once the script has completed, you should be able to see a new directory structure, something along the following lines.

Each folder is now its’ own git repository with it’s own internal version history, tags, branches etc.
cd into one of the folders and do a git log just to confirm you still have history.

The original projects.git can be removed (after backing it up for safety’s sake) if you’re satisfied everything is in place. We’re now ready to proceed with the next stage of the game, namely backing up our new git repositories to a remote share.

Step 3 – Backing up Git

I use a 2TB removable disk as a central data server for sharing files throughout my network. My thinking is that should the place ever burn down and I have the opportunity, there’s only one box I need to grab before rushing out the door. Of course, I burn frequent snapshots of this box to DVD.

I have created a ‘backups’ share on the disk which I map to my physical server using NFS.

The entry in my /etc/fstab file is something like this.

This means I can read/write to my backups folder as if it was a local folder on a local disk.

The job at hand is to be able to backup my git repositories using a cron task scheduled to run when everything is nice and quiet. Below is the script I use to run my git backups.

Once this script is run, you ‘ll have a copy of all your repositories in the backup folder. The next time it’s run should only take a fraction of the time as it won’t have to reestablish the git repository again.

So there you have it, migrating a subversion repository to git is really simple, the fun starts when you try to play with the results. I hope this has been helpful to others faced with the same job. Any improvements please let me know.

Ubuntu 10.04 setup for Ruby on Rails and general use

This extract is from notes I took during the process of setting up both a desktop and laptop for general use as a development environment for Ruby on Rails (RoR) and PHP development.

There were lots of other steps (custom gems and environment stuff I like), but most of what follows is generic enough to get the basics in place. Happy Hacking!!

#Install Skype
sudo apt-get install libqt4-dbus libqt4-network libqt4-xml libasound2
sudo dpkg -i skype-ubuntu-intrepid_2.1.0.81-1_amd64.deb

#Install Amarok
sudo apt-get install xine-ui libxine1-ffmpeg

##
#To get remote shares mapping in fstab
##

#install the smb client package
sudo aptitude install smbfs

sudo apt-get install portmap nfs-common

#Add the following line to /etc/hosts.deny:
echo portmap : ALL>>/etc/hosts.deny

#By blocking all clients first, only clients in /etc/hosts.allow below
#will be allowed to access the server.

#Now add the following line to /etc/hosts.allow:
echo portmap : NFS server IP address>>hosts.allow

sudo mkdir /mnt/
…etc
sudo mkdir /mnt/music
…etc
sudo mkdir /mnt/backups

Create a file in home folder called .smbcredentials (note the leading dot)
touch ~/.smbcredentials
echo username=
echo password=
chmod 600 smbcredentials

Now an entry in /etc/fstab
#Added a permanent share to shares on NAS box
#Note: everything that follows (up to the 0 0 should appear on the one line)
#and one line is required for each share you want to map

//192.168.0.20/ /mnt/ cifs
uid=peter,credentials=/home/peter/.smbcredentials,domain=office,dir_mode=0777,file_mode=0777 0 0

#setup filezilla
sudo aptitude install filezilla

#Limewire – download LimeWireLinux.deb from limewire site
# reports missing dependencies
peter@enspire:~/Downloads$ sudo dpkg -i LimeWireLinux.deb
limewire-basic depends on sun-java6-jre | icedtea-java7-jre |
sun-java6-jdk | icedtea-java7-jdk; however:
Package sun-java6-jre is not installed.
Package icedtea-java7-jre is not installed.
Package sun-java6-jdk is not installed.
Package icedtea-java7-jdk is not installed.
dpkg: error processing limewire-basic (–install):
dependency problems – leaving unconfigured

#Open synaptic package manager.
#Go to the Settings/Repositories/Other sources tab.
#Check the two default partner sites.

#Reload the package list and select the following
#sun-java6-jre
#sun-java6-plugin
#sun-java6-fonts packages

##
# Installing ruby and associated gems
##

sudo apt-get install ruby

sudo apt-get install rubygems

sudo gem install rake
sudo gem install rails

#tried to install capistrano using sudo but it wasn’t working on laptop
#however it did work on desktop
#sudo gem install capistrano
# or without sudo…
#gem install capistrano

#changed ~/.bashrc to include path to new gems
#Added PMGF 2010-06-24
export PATH=$PATH:~/.gem/ruby/1.8/bin:/var/lib/gems/1.8/bin

###
# Now install and configure mysql before trying to install any of the ruby mysql gems
###

#install mysql server
sudo apt-get install mysql-server
#setup prompts you for a password – enter it, remember it and enter it again.

#install the mysql admin tools
sudo apt-get install mysql-admin

#NB – must install the libmysqlclient[nn]-dev package
# this has mysql_config bundled with it which is needed by the ruby gems

#execute the following to find out what version of libmysqlclient yo’re running

dpkg –get-selections | grep mysqlclient

#in my case it’s version 16, so execute the following

sudo apt-get install libmysqlclient16-dev

#Next, you NEED TO INSTALL the ruby1.8 dev package
#If you don’t you’ll get all sorts of mysql gem errors — frustrating!!!
sudo apt-get install ruby1.8-dev

#now go for the mysql gem
sudo gem install mysql

###
# Installing and configuring git
###

sudo apt-get install git-core
git config –global user.email

###
# Installing apache
###
sudo apt-get install apache2
#the line above should do it, if you get any glitches, try the following
#sudo apt-get install apache2.2-bin
#sudo apt-get install apache2.2-common
#sudo apt-get install apache2-threaded-dev

###
# Installing php
###
sudo apt-get install php5
sudo apt-get install php5-mysql

Linux Command Line Tips

This list of commands is pretty much a copy found on Pádraig Brady’s site PixelBeat. It’s reproduced here for personal convenience.

Note:The commands with the • in the left hand column are safe to copy and paste as is.

ClamAV – Antivirus Scanner on Fedora8

I’ve just spent the best part of two hours fighting with the set-up of clamav on a relatively new Fedora 8 Server.  The documentation wasn’t the greatest so I’ve decided to do my bit to patch some of the holes.

Download clam

A number of instances of the clamd daemon can run concurrently. Each instance needs to be provided with a unique name. To keep things simple, we’re going to run one instance and call it ‘server’. This name has implications for what is to follow.
Setting up the daemon up as running service involves the following steps:

Phase 1 – create a daemon user

When you install clamav using the yum utility, a new user is created automatically – The user is clamav. Most documentation uses this user as the daemon user – this isn’t a good idea. The clamav user has rights to update the database containig the list of known virii.   Create a new user clamd with no login rights.

Phase 2 – Copying and renaming config files

Copy assorted files from /usr/share/doc/clamav-server-nn.nn.nn/ (where nn is the version number of your install) to assorted folders, renaming them and modifying their content.

Phase 3 – Editing the configuration files

Start by editing the /etc/clamd.d/clamd.conf file.

Firstly, comment out the line saying Example in file clamd.conf

Phase 3 – Create the folders

Create the /var/run/clamd.server folder

Create the clamd log folder

Copy the clamd-wrapper to clamd.server

# cp /etc/init.d/clamd-wrapper /etc/init.d/clamd.server

Edit the CLAMD_SERVICE variable in the /etc/init.d/clamd.server file

CLAMD_SERVICE=server

Geez..this is getting complicated…one final step

Create a clamd.server file in /usr/sbin that links to the original clamd file

# ln -s /usr/sbin/clamd.server /usr/sbin/clamd

OK..all systems go…

now start the daemon

#etc/init.d/clamd.server start

If you want the daemon to start on reboot add it to the startup list using chkconfig

Hopefully you get the green light and have a running clamd daemon. If you don’t (check using ps auxw | grep clamd) please post a comment and let me know what grief you’re having.