Tag Archives: howto

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Amazon, who are most widely known for their online shop, has another project called Amazon Web Services (AWS) offering website authors a collection of very powerful hosting tools as well as hybrid cloud services.

This is not a sideline for Amazon – a recent conversation I had with an Amazon guy I met at a Barcamp revealed that in terms of revenue AWS exceeds the store – and it dramatically lowers the cost of entry for web authors. Using AWS it is possible to compete with the big boys without the need to mortgage your house for the data center and it solves many storage and scalability problems, what’s more – its pay as you go.

To be clear then, Amazon is now a hosting company, and its rather curious as to why people (Amazon included) are not making a big deal of this.

Anywho, I’ve recently had the opportunity to work on a few projects which use AWS extensively, and since I did run into a few gotcha’s I’d thought I’d jot some notes down here, more as an aide-mémoire as anything else.

Getting an AWS account

Before you begin, you’re going to need an account. So, head over here and create one.

Creating a server

You are going to want to create a server to run your code on. The service you need here is Amazon Elastic Compute Cloud (EC2), so sign up for EC2 from the AWS Management Console.

You are going to have to select an EC2 Image to start from, and there are a number of them available. An Image (called AMIs) is a snapshot of your server, its disks and any software you want to run. Once configured you can start one or more Instances of it, which are your running servers. If you want more control over your servers, consider getting unmanaged vps hosting.

Once you’ve configured your server, you can create your own image which you can share or use to boot other instances. This whole process is made infinitely easier by using an EBS based image. EBS is a virtual disk, these can be added like normal disks to your server – sizes 1GB to 1TB. EBS backed images store data to these disks and so configuration changes are preserved, additionally new server images can be cloned with the click of a button.

You can add extra disks to your server, but they must be in the same availability zone (datacenter) as your EC2 image and currently can’t be shared between EC2 instances.

So:

  • Save your sanity and use an EBS backed image – if you’re looking for a Debian or Ubuntu based one, I recommend the ones created buy Alestic. You can search for community managed images from within the management console, be sure to select EBS backed! For reference, the AMI I often use is identified as ami-209e7349.
  • Grab an Elastic IP and assign it to your image, point your domain at this.
  • Your goal is to build an AMI consisting of a ready to go install of your web project, so install the necessary software.
  • Note however, that you want to build your AMI so that you can run multiple instances of it in order to handle scalability. Since EBS disks can’t be shared you may have to change your architecture slightly:
    • Don’t store user data on the server – user icons etc – these can’t be shared across instances. Store these instead on Amazon S3 and reference them directly using URL where possible. Note, temporary files like caches are probably ok.
    • If you use a database, use MySQL, but only install the client libraries on your image – you won’t be using a local server (see below)!

Once you’ve configured your server create an AMI out of it, this can then be booted multiple times.

Using a database

The database service you will most likely want to use is called Amazon Relational Database Service (RDS) which can function as a drop in replacement for MySQL.

Sign up for it using the management tool, create a database (making note of the passwords and user names you assign) and allow access from your running server instance(s) via the security settings.

The database is running on its own machine, so make a note of the host name in the properties – you will need to pass this in your connect string.

Conclusion

AWS is a powerful tool, if you use it right. There is a lot more complexity to cover of course, but this should serve as a start.

I’ll cover the more advanced scalability stuff later when I actually get to use them in anguish (and get the time to write about it!)

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ProFTP is a configurable FTP server available on most *nix platforms.

I recently had the need to get this working and authenticating off a PHP maintained MySQL backend, and this post is primarily to aid my own memory should I ever have to do it again.

Installing ProFTP

In order to use MySQL as a back end you need to install some packages. If you’re using a Debian based distro like Ubuntu, this is easy:

apt-get install mysql-server proftpd proftpd-mod-mysql

The database schema

Next, you need to install the database schema to store your users and passwords.

CREATE TABLE IF NOT EXISTS users (
userid varchar(30) NOT NULL default '',
passwd varchar(128) NOT NULL default '',
uid int(11) default NULL,
gid int(11) default NULL,
homedir varchar(255) default NULL,
shell varchar(255) default NULL,
UNIQUE KEY uid (uid),
UNIQUE KEY userid (userid)
) TYPE=MyISAM;

CREATE TABLE IF NOT EXISTS groups (
groupname varchar(30) NOT NULL default '',
gid int(11) NOT NULL default '0',
members varchar(255) default NULL
) TYPE=MyISAM;

One important thing to note here – that caused me a fair amount of hair pulling when I tried to use encrypted passwords – is that the password field shown in many howtos on the internet is much too short. This causes the hashed password to be quietly truncated by MySQL when saved.

This results in a somewhat misleading “No such user found” error to appear in the logs when using encrypted passwords.

To end all argument I’ve allowed passwords up to 128 chars, but this field could probably be a good deal shorter.

The user table looks much like /etc/passwd and is largely self explanatory. The uid & gid fields correspond to a system user in most cases, but since we’re using virtual users they can largely be ignored. Homedir points to a location which will serve as the user’s default directory. Shell is largely unused and can be set to /bin/false or similar.

Configuring ProFTP

Next, you need to make some changes to the ProFTP configuration files stored in /etc/proftpd. While doing this it is handy to run proftp in debug mode from the console:

proftpd -nd6

proftpd.conf

  1. Make sure the AuthOrder line looks like:

    AuthOrder mod_sql.c

  2. Ensure that the following line is uncommented:

    Include /etc/proftpd/sql.conf

  3. For belts and braces I’ve included the following at the end, although I’m not entirely sure it’s strictly required:

    <IfModule mod_auth_pam.c>
    AuthPAM off
    </IfModule>

  4. Our users don’t need a valid shell, so:

    RequireValidShell off

modules.conf

  1. Make sure the following lines are uncommented:

    LoadModule mod_sql.c
    LoadModule mod_sql_mysql.c

sql.conf

  1. Set your SQL backend and ensure that authentication is turned on:

    SQLBackend mysql
    SQLEngine on
    SQLAuthenticate on

  2. Tell proftp how passwords are stored. You have a number of options here, but since I was using mysql’s PASSWORD function, I’ll defer to the backend.

    SQLAuthTypes backend

  3. Tell proftp how to connect to your database by providing the required connection details, ensure that the user has full access to these tables.

    SQLConnectInfo database@host user password

  4. Define your table structure in the format tablename fields….

    SQLUserInfo users userid passwd uid gid homedir shell
    SQLGroupInfo groups groupname gid members

Adding users

I manage users from within a PHP web application that I’m developing, but in a nutshell adding FTP users from this point is a simple insert statement looking something like:

mysql_query("REPLACE INTO users
(userid, passwd, uid, gid, homedir, shell)
VALUES
('$userid', PASSWORD('$password'), $uid, $gid, '$homedir', '$shell')");

Have fun!

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This Christmas I finally bit the bullet and treated myself to a shiny XBox 360. Ostensibly this was so that I could experiment with console development, but mostly I have used it to play Gears of War.

In a slight departure from what I usually talk about, I thought I’d quickly jot down how I got the wireless controller to work with my Ubuntu XBMC media PC.

The wireless controller provides a slightly more usable remote than my iPhone (which must first be unlocked making quick pauses impossible) or rather flaky wireless keyboard, so hopefully this will be useful to someone.

Getting started

My media PC currently runs Ubuntu Karmic with XBMC. To begin with you will need to install the XBox kernel driver (already installed on Karmic).

Most importantly however, you will need to get yourself a XBox wireless gaming receiver for Windows – which I got included with my second controller. Xbox controllers do not use standard bluetooth, so you can’t just pair in the normal way using your existing hardware.

This howto has some more info…

Configuring XBMC

Assuming you have your module installed and controller paired you will need to tell XBMC about it by configuring a keyfile:

  1. I used this keyfile as a starting point. Download and save it as ~/.xbmc/userdata/keymaps/Keymap.xml (note case).
  2. Find out what your computer thinks the controller is by looking at the output from: cat /proc/bus/input/devices – you want a "Name" that says something like "Xbox 360 Wireless Receiver"
  3. Replace all occurrences of "Microsoft Xbox Controller S" with this value.

At this point if you start XBMC it should respond to the controller. If you are lucky this is all you will have to do, however for me I had to mess around with the key bindings a bit since the example keymap file didn’t match my controller exactly.

If this happens to you there’s not much I can suggest other than to bind one key at a time, restart XBMC and see what button that maps to then repeat until all your keys are mapped. I’m sure there must be an easier way that I’ve overlooked, feel free to comment below!

For what it’s worth, here is my modified (but somewhat incomplete) key file which has largely sensible bindings. Hack away to get it working how you like.

» Modified Keymap

Image “XBMC” by Miskan