Working With Amazon EC2: Tips & Tricks

It’s been a while now since I’ve been hosting on Amazon Web Services and I’d just like to point out some issues I had and quick ways of solving them. We’re gonna talk about setting up a server that would serve not only you, but your clients too, cause $100/mo is quite expensive, isn’t it? So let’s begin and keep this as straightforward as possible. If you don’t understand something, it’s probably because you haven’t read the official EC2 docs and haven’t searched the forums. This is not a tutorial, it’s just a set of rules you may want to follow to make things right.

Once you start a new instance from an Amazon predefined AMI (Fedora Core 8 for example) I suggest you start building your structure right straight away. Attach an EBS volume to you instance (I mount it to /ebs) and start creating your users with their home directories in /ebs/home/kovshenin not the regular /home/kovshenin. Also point your MySQL server to keep your database files in /ebs/mysql. There are plenty tutorials out there on how to do that.

Now, edit your httpd.conf, add your vhosts, point them to the right users dirs, install an ftp server and make sure you chroot the users to their home directories. That way they won’t be able to mess up with eachothers files and folders, peek passwords etc. You might want to change the root user’s home directory to / instead of /root in case you’ll want to use ftp via your root user (which is quite dangerous).

Now comes the fun part. The HTTP server runs under the apache user by default in FC8 and I recommend you don’t touch this. Damn it took me quite some time to figure out how the heck can the apache user execute and write to files not belonging to apache. I messed up big time with the groups, adding apache to all my client’s users groups, but thank god I found mod_suphp in the end. Install that one and make sure you use it and there’s no need to change the users umasks anymore.

Note: There’s a little issue with the mod_suphp in Fedora as far as I know, which doesn’t let you use the suPHP_UserGroup directive in the httpd.conf yelling that it does not exist. Most of the man pages on the net say you have to use that directive, but I’m good without it. It seems that suphp can figure out what user to run on its own, look closely at the config files, and also make sure you’re running php-cgi, not the CLI version. By the way, this is the part where WordPress stops asking you your FTP credentials on plugins/themes update, install, remove and core upgrade too. Speeds up the whole process ;)

I used the following code to test how mod_suphp works (or doesnt):

<?php echo system("id"); ?>

Which should output what’s the current user. Make sure you check everything works before going public, and do not set your min_uid and min_gid in suphp lower than 50. It’s safer to chown -R files and folders than to let suphp run your scripts via root or some other powerful user.

Backing up your EC2 and EBS

This is very important. Once you have everything set up and running, DO backup. Backing up the EBS is quite simple, just create a snapshot from the Amazon EC2 Management Console. Backing up the running AMI (instance) is a little bit mroe complex. You have to use the ec2 command line tools to bundle a new volume, upload it to an Amazon S3 bucket and register the AMI. There are plenty tutorials on the net on how to do that. Shouldn’t take you more than half an hour to figure it out.

Just make sure you have copies of all the major config files (httpd.conf, crontab, fstab, ..) backed up on your /ebs/config for instance. You might need them in the future (when you loose everything, haha ;) Restoring a backed up AMI instance is simple. Launch a new instance using the AMI you generated, attach the Amazon Elastic IP address to it and voila. Way too simple.

About the EBS, there are quite a few things you should be able to do with it before continuing. Restoring a backed up Snapshot: Create Volume from Snapshot, umount /ebs, deattach old volume, attach new volume, mount /ebs. Cool? Be careful when you’re resizing your EBS. The xfs filesystem automatically grows as far as I know, but in my case I use the ext3 filesystem. So if you need to grow your ext3 EBS you’ll go:

  1. Create a Snapshot
  2. Create a new EBS Volume from that Snapshot you created (say 10 GB if you were running 5 GB)
  3. Attach it to your Instance, say /dev/sdg
  4. Use the resize2fs command to resize the partition to 10GB
  5. Mount it to /ebs2 or whatever
  6. Check to see if everything’s in place
  7. Unmount /ebs2, deattach /ebs2, unmount /ebs, deattach /ebs
  8. Attach the 10GB volume to where /ebs was attached (/dev/sdf)
  9. Mount /ebs and start your services

There you go, back to work, server. By the way, when working with Amazon AWS, note that you should be working in the same region where your AMI is (us, eu, east, 1c, …) otherwise some of the options (when attaching, etc) might just not come up. Beware of that.

Well, I guess those are pretty much all the basics. Don’t forget to read the Amazon S3 tutorials and API, pretty sweet stuff! Good luck.

5 thoughts on “Working With Amazon EC2: Tips & Tricks

  1. Working With Amazon EC2: Tips & Tricks // | bllogger

  2. Can you tell more on setting mod_suphp on ec2? how to make it work and what to chown folders to on user accounts etc…

    may be you may even write a new article on suphp?

  3. I must convey my admiration for your kindness for folks that absolutely need help on the matter. Your real dedication to passing the message along has been rather productive and have specifically enabled employees like me to arrive at their objectives. The valuable suggestions entails a whole lot a person like me and substantially more to my fellow workers. With thanks; from everyone of us.

Comments are closed.