Just got rolling with a VPS on Linode (Part 2)

Posted by Jeff Beeman on Wed, 01/16/2008 - 23:48

Now that I had a demonstrably working and functional web server going on my Linode (see Just got rolling with a VPS on Linode (Part 1)), it was time to get the rest of my toolkit on the box, setup users and secure the server a bit.

Installing Subversion and migrating repositories

Well, installing Subversion couldn't be any simpler:


apt-get install subversion

Login to old server and dump current repositories:


svnadmin dump /path/to/repository > repository.dump

Copy dump file to new server, and on new server:


svnadmin create /path/to/repository
svnadmin load /path/to/repository

Adding users and groups

I decided I didn't want to be logged in as root all the time, especially since I'll most likely be bringing some other folks in to work on the server in the future. So, I setup the admin group, created myself a new user and put myself in both the admin and staff groups.


addgroup admin
adduser jrbeeman
usermod -G staff,admin jrbeeman

Next, I wanted to make sure admins could sudo to root, so that they could install programs and do other root-y things. The sudoers file, as far as I can tell, can only be edited with the command visudo:


visudo

...and added the line:


%admin ALL=(ALL) ALL

Setting up the firewall

This was probably the least-traveled territory in the whole VPS setup for me. Thankfully, there is an awesome resource in the website IP Tables Rocks, with a full rundown of how to lock down unneeded ports. It emphasizes locking down everything, and then only opening up those services you want open. I essentially followed the tutorial, but proceeded to lock down every port except those that I knew I would need for web services and working with the server (22, 80, 443, etc.)

Performance

By this point, I've started working on getting the Gamers With Jobs development site migrated over, and I'm working on nailing down any performance issues. As I said in part 1, the main reason for going to a VPS was the sheer size and load on the GWJ site and how shared hosting was really hosing the speed. Most of the tweaks from here on out are related to the GWJ site.

Tweak MySQL settings

Since the Gamers With Jobs site is very database intensive, getting MySQL to perform optimally given the site's load is important. I'm still tweaking these settings here and there, but here's what I'm at so far. I'm attempting to go for large enough buffers and caches to keep things snappy, but without bloating out the caches to the point that things slow down.


#
# * Fine Tuning
#
key_buffer = 256M
max_allowed_packet = 16M
thread_stack = 128K
thread_cache_size = 8
#max_connections = 100
table_cache = 256
thread_concurrency = 4
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
#
# * Query Cache Configuration
#
query_cache_limit = 1M
query_cache_size = 16M
#
# Turn on slow query logging to help track down performance killers
#
log_slow_queries = /var/log/mysql/mysql-slow.log
long_query_time = 5
#
# Some further table-type tweaks
#
[isamchk]
key_buffer = 128M
sort_buffer_size = 128M
read_buffer = 2M
write_buffer = 2M

[myisamchk]
key_buffer = 128M
sort_buffer_size = 128M
read_buffer = 2M
write_buffer = 2M

Bringing over the GWJ site required quite a bit of scripting of INSERT and DELETE statements that fudged with table lengths, so I also optimized all the tables with free data space:


-- Get the table names...
SHOW TABLE STATUS WHERE Data_free > 0;
-- ...and run the following for each
OPTIMIZE TABLE table_name;

Tweak Apache settings

The YSlow utility from Yahoo is a great way to track down potential end-user performance issues, so I ran it against the GWJ dev site and tweaked quite a few things to improve the rating and speed reported there.

First, I needed to enable a few Apache modules:


a2enmod deflate
a2enmod expires
a2enmod cache

Then, in /etc/apache2/httpd.conf, I added the following lines to the stanza of the GWJ virtual host definition:


# Gzip html, css, js, etc.
AddOutputFilterByType DEFLATE text/html text/css text/plain text/xml application/x-javascript application/json
# Set expires headers on html, css, js, etc.

ExpiresActive On
ExpiresByType text/html "access plus 1 seconds"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType text/css "access plus 1 week"
ExpiresByType text/javascript "access plus 1 month"
ExpiresByType application/x-javascript "access plus 1 month"

# Set ETags
FileETag MTime Size

Install memcached

In order to squeeze a bit more performance out of the server, I decided to install memcached and the related Drupal module, which allows you to configure Drupal to store certain cache data in memory. I essentially followed the instructions in Robert Douglass's article on Lullabot, but with a couple of modifications.

First, libevent1-1.3b and memcached-1.2.1-1 can be installed via apt-get on Ubuntu gutsy, all with:


apt-get install memcached

Then, I enabled the Apache module:


a2enmod mem_cache

Install eaccelerator

Not much to write here, aside from noting that I followed the great article on 2Bits to get going.

Done... sorta

Seeing how I started writing this article a couple of weeks ago and am just getting around to publishing it, I think I'll call it "finished," for now. I hope that someone out there finds this useful!