Gwik's corner

Working for a new client on a Rails project, I decided to give a shot at Git.

I’m working with an other developer who holds the svn repository. He is the only person allowed to commit to the trunk and I have to commit to my own branch. At first, this doesn’t seemed to be a problem. But there is a lot of files modified every day on the trunk and I’m constantly merging from the trunk to keep my branch up to date. Git seems to have some nice features that could help me to avoid those constant merges.

I writing this article while installing git so I don’t already know if it is the solution to my troubles. I just read this article and it convinced me to give git a try.

I have to mention that I never worked with git before so I will discover git with this project and we’ll see if it’s reasonable. I heard about git on rubyinside blog a few weeks ago.

So, as I’m on leopard, the easiest way (for me) to build git is macports so let’s do it.

sudo port install git-core +svn

This installs all git git-svn and gitk. All ran smoothly for me. If it fails try this install tutorial for leopard.

Now it’s installed properly I need to build my git project from subversion repository

daiquiri% git svn init https://repos.../trunk
Initialized empty Git repository in .git/

It doesn’t checkout the sources so let’s check this previously mentioned article to see what I do next.

svn info https://repos.../trunk

git-svn fetch -r3741
.
.
...The checkout happens...
.
.
r3741 = b444a88efc7248dfdd5f96a7dd7e36165a0f3ed6 (git-svn)
Checking 4130 files out...
 100% (4130/4130) done
Checked out HEAD:
  https://82.240.32.108/svn/eco-sys/trunk r3741

It seems all went ok and that my git project is ready to go.

I little config seems to make things a little prettier. I took this from here

git config --global user.name "Antonin Amand"
git config --global user.email "aamand@gwikzone.org"
git config --global color.status auto
git config --global color.diff auto                                             
git config --global color.diff auto
git config --global color.branch auto
git config --global merge.tool opendiff
git config --global core.excludesfile ~/.gitignore
echo ".DS_Store" >> ~/.gitignore
cat > ~/.gitk <<EOF
set mainfont {Monaco 10}
set textfont {Monaco 10}
set uifont {Monaco 10}
EOF

I will know do some changes in the configuration to get the working on my mac. I understood that the best practice is to create a new branch.

git checkout -b localconfig HEAD

This creates a new branch a switch in it immediatly.

git add mymodifiedfile
git add ...
git commit

git commit -a

Now I’ve seen that the other developer add update a lot of files in the trunk. So I will try to update my git branch.

git svn rebase

This first revert your repository before my modifications update from subversion and apply again my commit. All went nicely. Notice that it is extremely more powerfull that trying to apply the update directly on the modified sources.

Now I want to commit to the remote svn, but the other developer don’t allow me to commit to the trunk. I will create a patch with git, create a new branch in the subversion repository from the trunk, apply the patch and then ask for the developer to merge changes from the new branch to the trunk.

git format-patch remotes/git-svn

Then I create the branch into the subversion repository and checkout.

svn copy http://repos/trunch http://repos/branches/merge-branch
svn checkout http://repos/branches/merge-branch
cd merge-branch

Now I need to apply the patch.

patch -p1 < /path/to/thepatch

svn commit

Now I just have to send an email to the other developer.

With this first shot, I am conviced that git will improve my merging process and be a lot more flexible that SVN.

Now that I will play a lot with patches, next time I’ll probably take a look at StGIT (Stacked Git), patch management utility.

As many users of mac OS X, I’ve encountered some troubles with the backspace key when ssh into a debian machine.

Reading some posts on the web, I was thinking that the problem was about the shell or the tty. But in fact it was related to zsh.

The default zsh map on debian is not correct for mac users. The solution is to tell zsh how to bind keys.

echo "bindkey ^? backward-delete-char" >> ~/.zshrc
echo "bindkey ^[[3~ delete-char" >> ~/.zshrc

Use ctrl+v [key] to generate the ^... characters.

Here is a way to extract a sample image from a video with ffmpeg :

$ ffmpeg  -itsoffset -4  -i sample.mov -vcodec png -vframes 1 -an -f rawvideo -s 320x240 test.png

• -itsoffset -4 : means that you want to extract the image 4 seconds after video starts.

Mongrel is a very fast and secure server for Ruby On Rails applications. It also supports Nitro and Camping. Setting up a mongrel_cluster on Mac OS X is not very difficult but it is a bit different from other Unix platforms.

• rubygems
• MacPorts(DarwinPorts)

Step 1 : Install Mongrel

Mongrel is available for unix platform and Win32 systems as a gem.

$ sudo gem install mongrel mongrel_cluster

Installing Apache 2.2

You can compile it from sources. But it is easier to install it via MacPorts.

$ sudo port install apache2

All apache2 files will be installed in /opt/local/apache2, including binaries and configuration files.

Setting up Apache 2.2

$ cd /opt/local/apache2/conf
$ sudo cp httpd.conf.sample httpd.conf

Create a new directory that will contain your application specific configuration files for Apache.

$ sudo mkdir myapp
$ cd myapp

Create 3 files for your new application. (adapted from codahale blog)

$ sudo touch myapp.common myapp.conf myapp.cluster.conf

Here is the files content :

myapp.common :

  ServerName www.myserver.com  
  DocumentRoot /path/to/my/app/public

  <Directory "/path/to/my/app/public">
    Options FollowSymLinks
    AllowOverride None
    Order allow,deny
    Allow from all
  </Directory>

  RewriteEngine On

  # Make sure people go to www.myapp.com, not myapp.com
  RewriteCond %{HTTP_HOST} ^myapp.com$ [NC]
  RewriteRule ^(.*)$ http://www.myapp.com$1 [R=301,L]
  # Yes, I've read no-www.com, but my site already has much Google-Fu on
  # www.blah.com. Feel free to comment this out.

  # Uncomment for rewrite debugging
  #RewriteLog logs/myapp_rewrite_log
  #RewriteLogLevel 9 

  # Check for maintenance file and redirect all requests
  RewriteCond %{DOCUMENT_ROOT}/system/maintenance.html -f
  RewriteCond %{SCRIPT_FILENAME} !maintenance.html
  RewriteRule ^.*$ /system/maintenance.html [L]

  # Rewrite index to check for static
  RewriteRule ^/$ /index.html [QSA] 

  # Rewrite to check for Rails cached page
  RewriteRule ^([^.]+)$ $1.html [QSA]

  # Redirect all non-static requests to cluster
  RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f
  RewriteRule ^/(.*)$ balancer://mongrel_cluster%{REQUEST_URI} [P,QSA,L]

  # Deflate
  AddOutputFilterByType DEFLATE text/html text/plain text/xml application/xml application/xhtml+xml text/javascript text/css
  BrowserMatch ^Mozilla/4 gzip-only-text/html
  BrowserMatch ^Mozilla/4.0[678] no-gzip
  BrowserMatch bMSIE !no-gzip !gzip-only-text/html

  # Uncomment for deflate debugging
  #DeflateFilterNote Input input_info
  #DeflateFilterNote Output output_info
  #DeflateFilterNote Ratio ratio_info
  #LogFormat '"%r" %{output_info}n/%{input_info}n (%{ratio_info}n%%)' deflate
  #CustomLog logs/myapp_deflate_log deflate

myapp.conf :

<VirtualHost *:80>
  Include /opt/local/apache2/conf/myapp/myapp.common

  ErrorLog /path/to/logs/error.log
  CustomLog /path/to/logs/access.log combined
</VirtualHost>

myapp.cluster.conf :

<Proxy balancer://mongrel_cluster>
  BalancerMember http://127.0.0.1:8000
  BalancerMember http://127.0.0.1:8001
  BalancerMember http://127.0.0.1:8002
</Proxy>

Now that your files are created. at this to the bottom of /opt/local/apache2/conf/httpd.conf

NameVirtualHost *:80

Include conf/myapp/myapp.conf
Include conf/sites/myapp.cluster.conf

Apache is now ready to run.

Setting up Mongrel cluster

Create a new dir for mongrel cluster config

mkdir /opt/local/etc/mongrel
cd /opt/local/etc/mongrel

And create a new file “myapp.yml”

--- 
user: www
group: www
port: "8000"
cwd: /path/to/your/app/root
environment: production
address: 127.0.0.1
pid_file: log/mongrel.pid
servers: 3

Setting up Startup Scripts

Enable apache startup script

$ sudo vi /etc/hostconfig

#add the following lines

APACHE2=-YES-
MONGREL=-YES-

Copy the following into /Library/StartupItems/mongrel_cluster/mongrel_cluster

#!/bin/bash
#
# Copyright (c) 2006 Bradley Taylor, bradley@railsmachine.com
#
# mongrel_cluster       Startup script for Mongrel clusters.
#
# chkconfig: - 85 15
# description: mongrel_cluster manages multiple Mongrel processes for use \
#              behind a load balancer.
#              

[ -r "/etc/hostconfig" ] && . "/etc/hostconfig"

CONF_DIR="/opt/local/etc/mongrel"
RETVAL=0
ENABLE_FLAG=${MONGREL:=-NO-}

if [ "${ENABLE_FLAG}" = "-NO-" ]; then
        echo "Mongrel is disabled. see /etc/hostconfig"
        exit 0
fi

case "$1" in
    start)
      mongrel_cluster_ctl start -c $CONF_DIR
      RETVAL=$?
  ;;
    stop)
      mongrel_cluster_ctl stop -c $CONF_DIR
      RETVAL=$?
  ;;
    restart)
      mongrel_cluster_ctl restart -c $CONF_DIR
      RETVAL=$?
  ;;
    *)
      echo "Usage: mongrel_cluster {start|stop|restart}"
      exit 1
  ;;
esac      

exit $RETVAL

ffmeg is a command-line tool for video encoding which has the ability to encode videos in FLV format (Macromedia plugin for direct-streaming).

First, you need to install ffmpeg with liblame support.

You may grab it as package or compile from sources.

We will compile from sources in this article for more compatibility.

first step : Installing lame get sources at http://lame.sourceforge.net, untar the archive and chdir to unpacked sources directory.

$ ./configure && make && sudo make install

second step : Installing ffmpeg

Getting sources from svn :

 $ svn export svn://svn.mplayerhq.hu/ffmpeg/trunk ffmpeg

Change dir to ffmpeg and compile with liblame

$ ./configure --enable-mp3lame && make && sudo make install

Your now setup. You can continue with encoding your first video

$ /usr/local/bin/ffmpeg  -i input.mov -ar 22050 -ab 56 -aspect 4:3 \
 -b 200 -r 12 -f flv -s 320x240 -acodec mp3 -ac 1 output.flv

to view the result download a swf FLV player and create a html file :

<html>
<head>
<title>Flash FLV Player</title>
</head>
<body>
<h3>My First FLV video</h3>
<object type="application/x-shockwave-flash" width="320" height="260" wmode="transparent" data="flvplayer.swf?file=output.flv&amp;autoStart=false">
<param name="movie" value="flvplayer.swf?file=output.flv&amp;autoStart=false" />
<param name="wmode" value="transparent" />
</object>

</body>
</html>

Enjoy !

Favicon are little icons that you can see in your browser before URL address.

To create this icons on unix-likes proceed as follow.

Open your favourite Image manipulator program, for me It will be The GIMP.

Create a 16×16 px PNG, and optionally a 32×32 px PNG.

Install png2ico from sources, package or compile it via darwinports.

For OS X with darwinports :

$ sudo port install png2ico

and create your favicon file :

$ png2ico favicon.ico favicon16.png favicon32.png

Now that you have your favicon file, just put it in your web server root directory.

You can had the following for IE compatibily in your web pages :

<link rel="icon" href="/favicon.ico" type="image/x-icon" />
<link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" />

I’m originally a Linux user. Then, in Linux lookup default order is to look first in /etc/hosts file and then to launch the dns query.

But In OS X default is to search to into NetInfo DB first.

To change this behaviour you have to change the configuration of the lookup daemon.

$ cd /etc

#if lookupd directory doesn't exists create it
$ sudo mkdir lookupd

$ cd lookupd

$ sudo echo LookupOrder Cache FF NI DNS DS > /tmp/hosts

$ sudo mv /tmp/hosts .

# reload configuration of lookupd

$ sudo lookupd -configuration

All right, you’re now setup the old fashion way.

ARDAgent (Apple Remote Desktop Agent) sometimes freeze and then it may be impossible to control your remote server.

Here is the command line to restart it.

# ssh into you machine

$ ssh user@host

# locate the restart script
$ locate kickstart
/System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart

# restart the agent
$ cd /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources

$ sudo ./kickstart -restart -agent 

The point of this blog is not to talk about my life but for this time I’ll make an exception.

Luck comes when you doesn’t expect it.

After six month of great frustration with my iBook cause it doesn’t stop to crash, I decide to buy the new Macbook.

So, I go to my favorite store with the intention to buy the cheapest macbook. But when i arrive to the shelf, I discover that the 1GBram – DVDWriter – 2Ghz intel is sold at a reduced price (about less $150). It’s still more expensive but I decide to buy it. Unfortunatly, they doesn’t have it anymore, I have to go an other store (30 miles further) which is supposed to have it at the same price.

But when i arrive, they don’t have anymore. Sadly, I decide to take the one i came for at the first time, the cheapest. I’m not so sad, I have my new Macbook anyway, and I spent less money.

I come back home, unpack, plug, configure, and start to look at the system info tool. This is a this moment that I figure out there where a mistake in the labelling and that I have bought the more expensive one at the price of the cheapest.

Yes, this happens only to others, except for me ;)

If like me you use a up to date zsh shell under Mac OS X installed via DarwinPorts (which change name to MacPorts) you may want to set it as your default shell.

To do this in a proper way (not by changing it in Terminal.app Preferences) you should proceed as following.

$ sudo vi /etc/shells
# add the following line : 
/opt/local/bin/zsh
$chsh
# and change /bin/bash to /opt/local/bin/zsh