Installing Node.js 0.8.x under CentOS 5.8
Tuesday, 24th July 2012, 14:13

So, the 0.8 branch of Node.js hit a few weeks ago now, and we have had some updates (to 0.8.3 at the time of writing) as well. Certainly my initial attempts at upgrading to it resulted in a quick jump back to the tried and tested 0.6.x stable versions, partly because it always takes module maintainers a few weeks to get up to speed, and there is always a straggler who is busy with other commitments and not managed to do it yet.

Well, I think now is the time to move, certainly for me. Everything I rely on appears to work fine under 0.8.x, so I'm going to take my live server and make the jump my test server has been flirting with on and off ever since it came out.

The only snag is, node-waf has been depreciated and in its place is node-gyp, something that helps to make cross platform compatibility easier. On its own, no big deal, unless you run CentOS 5.8 in which case it is, as that requires a newer version of Python than we have installed.

You'll have no doubt encountered this the moment you tried ./configure in the extracted node 0.8 directory. An error message like this probably appeared pretty quickly:

prompt# ./configure 
  File "./configure", line 273
    o['default_configuration'] = 'Debug' if options.debug else 'Release'
                                          ^
SyntaxError: invalid syntax

The cause? Python 2.4. So just upgrade Python you say! It isn't quite that easy, as parts of the CentOS system are based on specific versions which shouldn't be changed during the long life cycle of the OS version, and Python is one of those. So we are stuck with 2.4 as our base one, but don't be disheartened, we can still manage it if we get a bit fiddly.

Step One - Installing Python 2.6

We are definitely not going to install this from source, because we need to preserve the 2.4 version for the base OS and only swap to 2.6 when required.

First job is to add a repository that contains it, and will let us install alongside existing ones. For this we use the Extra Packages for Enterprise Linux (EPEL) repo as recommended on the official CentOS Wiki page, so run the following as root:

prompt# rpm -i http://dl.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm

This will add two repos to your /etc/yum.repos.d directory:

epel.repo
epel-testing.repo

Now we can install the 2.6 version, again as root:

prompt# yum install python26

This should install three packages, and will probably also ask you about importing a GPG key to which you should say yes. You should now have the following installed:

python26
python26-libs
libffi

Finally, we'll use the alternatives program to let us swap between Python versions:

prompt# alternatives --install /usr/bin/python python /usr/bin/python2.4 20
prompt# alternatives --install /usr/bin/python python /usr/bin/python2.6 10
prompt# rm /usr/bin/python
prompt# alternatives --auto python

Don't panic about removing the python executable, because it's actually a copy of /usr/bin/python24. The last line creates the symlink for whatever is the highest priority, which isn't the lowest number provided when installing but the highest, so in this case Python 2.4 is effectively the default.

Now just make sure the version you are running by default is still 2.4 by trying it:

prompt# python
Python 2.4.3 (#1, Jun 18 2012, 08:55:23) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-52)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

Press CTRL-D to exit, then run alternatives --config python and select 2.6:

prompt# alternatives --config python

There are 2 programs which provide 'python'.

Selection Command
-----------------------------------------------
*+ 1 /usr/bin/python2.4
   2 /usr/bin/python2.6

Enter to keep the current selection[+], or type selection number: 2

prompt# python
Python 2.6.8 (unknown, Apr 12 2012, 20:59:36) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-52)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

All good, just remember when you need to use any module that requires node-gyp, run the alternatives config thingy and swap it to 2.6, then put it back to 2.4 so base CentOS stuff still works when you are finished.

Step Two - Installing Node 0.8

Now comes the easy bit, download Node 0.8.x, configure, install, run npm update and everything should be good to go.

prompt# cd /home/somewhere_you_download_files_to
prompt# wget http://nodejs.org/dist/v0.8.3/node-v0.8.3.tar.gz
prompt# tar zxvf node-v0.8.3.tar.gz
prompt# cd node-v0.8.3
prompt# ./configure && make && make install

prompt# cd /var/www/wherever_you_have_node_modules
prompt# npm update

Hopefully you have been sensible and kept the previous working 0.6.x release somewhere safe, so if you encounter problems you can always reinstall that.