Recently heroku upgraded and migrated their postgres database to a different stack – unfortunately that broke wordpress blogs hosted on heroku. I wrote a detailed article on how to host your wordpress blog on heroku some time back – I found a few very useful wordpress bootstraps for heroku. After the recent upgrade, all the wp-config settings were invalidated and your wordpress blog could not connect to the database. There are two things to notice :

• Your database is safe – its just moved and renamed
• You need to edit your wp-config to change the db settings to the migrated database

But, where on earth is my wp-config.php ? If you are like me, you dont have the original copy which you used to create your blog in the first place. Many of you might not have hosted that wordpress installation on github. So how to update the wp-config ?

Trick is to know that heroku internally has a github link to every app it hosts. You will need to find which github repo heroku is internally linking your application to and you will need to find the modified database name, username, password and host.

• Finding github repo for your app is easy. Login to heroku and click on the app that is used to host your blog.
• Check the ‘Settings’ tab and you will find something like – Git URL: git@heroku.com:yourapp.git
• <yourapp> is the actual name your app
• Now head back to your terminal and clone this particular repo as follows


git clone git@heroku.com:furious-robot-218.git -o heroku
Initialized empty Git repository in /Users/adam/facebook-template-php/.git/
remote: Counting objects: 273, done.
remote: Compressing objects: 100% (183/183), done.
remote: Total 273 (delta 2), reused 261 (delta 0)
Receiving objects: 100% (273/273), 25.55 KiB, done.
Resolving deltas: 100% (2/2), done.

• Once your code is cloned locally, head over to ‘Resources’ tab and you will find a link to ‘Heroku Postgres Dev :: Cobalt’
• Clicking on this link will show you a page where you will find the migrated DB name, username, password and host – Note these down
• Head back to your local terminal and edit wp-config.php file and modify the following with the new values :


/** The name of the database for WordPress */
define('DB_NAME', 'new_value');
/** MySQL database username */
define('DB_USER', 'new_value');
/** MySQL database password */
define('DB_PASSWORD', 'new_value');
/** MySQL hostname */
define('DB_HOST', 'new_value');

• Once you have updated wp-config.php with the modified values. Push it to heroku as follows:


$ git commit -am "changed greeting"
[master 0ff313a] changed greeting
1 files changed, 1 insertions(+), 1 deletions(-)
$ git push heroku
...


Thats it. Your modified settings are uploaded to heroku and your app is restarted.

Ever tried running Windows 7 as remote desktop using rdesktop? I always wonder why the earlier enabled ClearType settings are disabled on rdesktop. Try the following flag :
-x 0x80
More details on how to arrive at this flag – check this blog.

A few days back I came across a problem : Design a system with following APIs :

1. put(n) : Puts the value n
2. get() : Gets the first added value

Obviously, this was a queue because we want get() operation to return the element added first. Here the order of adding elements is important. So far, things look good. We create a Queue using a doubly linked list with head and tail pointer so that get() and put(n) are both O(1) operations.

How about adding one more operation to this system? We want to add an API – removeElement(n) – that removes an element n from the queue in best possible time. Hmm, we have a problem. What options do we have ?

Continue…

I read a lot of hype around how rbenv is the best thing since sliced-bread (RVM) – so on a fresh machine, I jumped ahead and installed rbenv instead of RVM – wow, and I loved it instantly. Setup was fast and nothing broke…umm, well not exactly.
I remembered that all my weekend hacks are hosted on servers crunching rubies out of RVM and I am still using Capistrano (with RVM integration) to remotely deploy my code.

Is there a way to use Capistrano with rbenv ? The problem is that passenger does not recognize rbenv’s rubies (check my stackoverflow – ) – so passenger can’t be spawned by nginx. I did not find any answers.
Finally, I removed rbenv and switched back to RVM (but not without problems).

One important thing to remember while installing RVM as root (you will be doing this on your own hosted machines) is that when you deploy your app with Capistrano, always add the following line to your deploy.rb file :

set :rvm_bin_path, “/usr/local/bin”

or you will hit – https://github.com/capistrano/capistrano/issues/43 while doing cap deploy:setup.

Some might find the notification area icons showing up in the Message Tray (at the bottom of the screen, hidden by default) annoying or confusing. But you can move the icon on the Top Bar using an extension:

sudo apt-get install git-core
cd
git clone https://github.com/rcmorano/gnome-shell-gnome2-notifications.git
sudo cp -r gnome-shell-gnome2-notifications/gnome-shell-gnome2-notifications@emergya.com /usr/share/gnome-shell/extensions/

Then press ALT + F2 and enter “r” to restart GNOME Shell.

Happened to stumble upon this fantastic writeup on microcaching. A must read.

http://fennb.com/microcaching-speed-your-app-up-250x-with-no-n

This weekend (and few more) are going to be very interesting. Stanford has opened up a great line-up of courses.

Ah! another post discussing Ubuntu 11.10 breakage. It seems that you can’t compile nginx module on passenger if you are on Ubuntu 11.10.

The error is something like :

common/libpassenger_common.a(aggregate.o): undefined reference to symbol 'pow@@GLIBC_2.0'

After some internet search, I found the following solution. Go to directory :

/home/ved/.passenger/standalone/3.0.8-x86-ruby1.9.2-linux-gcc4.6.1-1002/support/ext/nginx

(Your path may vary based on your installation).
Edit file : config and move the following block :

ngx_feature="Math library"
ngx_feature_name=
ngx_feature_run=no
ngx_feature_incs="#include"
ngx_feature_path=
ngx_feature_libs="-lm"
ngx_feature_test="pow(1, 2)"
. auto/feature
if [ $ngx_found = yes ]; then
CORE_LIBS="$CORE_LIBS -lm"
fi


after this block :

ngx_addon_name=ngx_http_passenger_module
HTTP_MODULES="$HTTP_MODULES ngx_http_passenger_module"
NGX_ADDON_SRCS="$NGX_ADDON_SRCS
${ngx_addon_dir}/ngx_http_passenger_module.c
${ngx_addon_dir}/Configuration.c
${ngx_addon_dir}/ContentHandler.c
${ngx_addon_dir}/StaticContentHandler.c"
NGX_ADDON_DEPS="$NGX_ADDON_DEPS
${ngx_addon_dir}/Configuration.h
${ngx_addon_dir}/ContentHandler.h
${ngx_addon_dir}/StaticContentHandler.h
${ngx_addon_dir}/ngx_http_passenger_module.h
${ngx_addon_dir}/../common/Constants.h"
CORE_LIBS="$CORE_LIBS
${ngx_addon_dir}/../common/libpassenger_common.a
${ngx_addon_dir}/../common/libboost_oxt.a
-lstdc++ -lpthread"


Try recompiling nginx again by “passenger start” – see if it works. If you are curious on how this works, take a look at

I recently upgraded my kernel to 3.0.0.12 and found VMPlayer failing to compile. After so much failed attempts to search over the internet, I failed to compile VMPlayer. VMWare has not provided any patches.

This article(see comment:56) is written for 3.0.0.9 but works fine for newer kernals also.


$ lsb_release -rd
Description: Ubuntu oneiric (development branch)
Release: 11.10

$ uname -a
Linux myUBT 3.0.0-9-generic #15-Ubuntu SMP Tue Aug 30 15:03:37 UTC 2011 i686 i686 i386 GNU/Linux

——-
STEPS:
——-
Close VMware dialog from where you got the error. (no need to uninstall/remove VMware)

sudo -i
mkdir /tmp/vmware && cd /tmp/vmware
cp -R /usr/lib/vmware/modules/source/
cp -R /usr/lib/vmware/modules/source/ /tmp/vmware
cd /tmp/vmware/source
wget http://weltall.heliohost.org/wordpress/wp-content/uploads/2011/05/vmware2.6.39patchv3.tar.bz2
tar -jxvf vmware2.6.39patchv3.tar.bz2
for i in ./*.tar; do tar -xf $i; done
for i in ./*.tar; do mv $i $i.orginal; done
patch -t -f -p1 < vmware2.6.39fixedv3.patch
tar cf vmblock.tar vmblock-only
tar cf vmci.tar vmci-only
tar cf vmmon.tar vmmon-only
tar cf vmnet.tar vmnet-only
tar cf vsock.tar vsock-only
cp -vf *.tar /usr/lib/vmware/modules/source/

Run VMWare Player

I recently read a few articles on how to deploy a wordpress blog on heroku. Interesting idea I thought. So how do we go about doing this ? Heroku recently announced their partnership and integration with Facebook Apps. Along with this announcement, or perhaps at an earlier time, Heroku’s Celadon Cedar stack can detect and support PHP applications. Although heroku says you can only create PHP application from Facebook that’s not entirely true.

There are ways to deploy wordpress (a PHP application) on Cedar stack of Heroku. In fact this blog IS running on wordpress hosted on heroku.

Here is how.

Assuming you have the Heroku gem and an account set up, create an empty project directory:

mkdir wp_blog
cd wp_blog
git init

Download the latest repository from wordpress -

wget http://wordpress.org/latest.tar.gz
tar xzvf latest.tar.gz;

Copy wordpress directory content to ‘wp_blog’ directory created earlier. Now you are ready to push the code to git.

git add .
git commit -am "Initial checkin"

Create your heroku app with Cedar stack

heroku create --stack cedar
git push heroku master

Now comes the most critical part. Heroku has a MySQL cloud database addon (Xeround) as an option but that is not open for all. But you can still use the default Postgres database support using Postgres WordPress plugin which allows the use of Heroku’s shared database as an addon.

Enable shared Postgres database support:

heroku addons:add shared-database:5mb

Check the database parameters from heroku’s environment:

heroku config
DATABASE_URL => "postgres://username:password@hostname/database"

Now, you can edit wp-config.php with the details from the DATABASE_URL entries. Make necessary changes to wp-config.php and push the modified to heroku.
That’s it.

One small thing is that you can not install plugins/themes using the normal methods because Heroku stack does not have the zlib support. You will have to download plugins and themes locally and push to heroku. Big deal…?