Sending Tweets from Amazon EC2

Given how unstable the EC2 microinstance I use is, I wanted to be able to automatically restart the blog related services and alert me that a restart had occurred.

I decided to try and get the alert via a tweet and doing this is actually pretty easy. All it consists of doing is:

1) Register a Twitter app at dev.twitter.com

2) Set up a new Twitter account  for your tweets to come from

3) Authenticate your new account with your new app

4) Configure something to use your app to send tweets from your new account

Luckily, this has all already been done by someone much cleverer than me, so I copied them! Have a look at this blog post by Jeff Miller explaining how to use the python Twitter API script Tweepy.

My EC2 instance already had python installed so all I needed to do was install git, get the tweepy code from the github repo here (the location of the github repo in the article is incorrect, so a little googling helped me find the correct location), and follow the instructions exactly!

Essentially this consisted of:

sudo yum -y install git
sudo git clone git://github.com/tweepy/tweepy.git
cd tweepy
sudo python setup.py install

Then follows some copying and pasting of auth keys and urls to end up with a nice script on the EC2 instance which was authorised to send tweets from my new twitter account, @rposboEC2.

All that was left was to link this into the startup script:

sudo nano /etc/rc.d/rc.local

by adding in a new line at the end and set the status to include my own twitter account so I see it as a mention and will therefore also receive an email alert automatically:

sudo python /home/ec2-user/tweepy/ec2Event.py '@rposbo EC2 microinstance event raised: Restarted'

Done! Firing off this script now restarts Apache and mysql and sends the tweet below:

EC2 Micro Instance Instability

It’s getting a bit daft now – the EC2 microinstance this blog is hosted on seems to keep restarting. When it comes back up, Apache and mysql are stopped, so the site is down.

As such, I’ve just logged in via SSH and fired off the command below to edit the startup script:

sudo nano /etc/rc.d/rc.local

Then added in the lines:

sudo /etc/init.d/httpd start
sudo /etc/init.d/mysqld start

Now whenever the microinstance restarts it will automatically restart Apache and mysql. I hope.

Just for good measure I also added in a line for logging so I have some idea of how often the instance restarts:

date >> /home/ec2-user/restartlog

I’ll add in an email alert or maybe just make it tweet the restart event as well.

Pretty Permalinks

Oh, one more on the EC2 Word press thing; if you want pretty permalinks (i.e., http://robinosborne.co.uk/2011/09/08/pretty-permalinks/ ‎ instead of http://robinosborne.co.uk/?p=85), and you’re running WordPress on an EC2 installation, before you select it in your WordPress “settings” section be sure to edit your Apache config first:

Pop open PuTTY (or whatever terminal you use), log in, run

sudo nano /etc/httpd/conf/httpd.conf

hit ctrl+W and type “override”, do it again until you see:

#
# AllowOverride controls what directives may be placed in .htaccess files.
# It can be "All", "None", or any combination of the keywords:
#   Options FileInfo AuthConfig Limit
#
    AllowOverride None

Change the None to FileInfo, hit ctrl+X to save and exit. Then restart apache with:

sudo /etc/init.d/httpd restart

Done. Hopefully. YMMV 😉

EC2 MicroInstance: The WordPress Hosting Wonder

I managed to not notice that my blog had gone down after the EC2 outage earlier this year. So when I popped back on one day to find it wasn’t there any more I was a little concerned.

Popped over to PuTTY, opened up my EC2 connection to be presented with a login screen. So I tried the old usual login: “root”

EC2 Login

Ok, let’s  try that then:

EC2 Welcome

BRILLIANT!!

Uh..

Now what?

Crap. I can’t remember.

I faffed around for ages with “ls”, checking out what’s in “/opt/” and “/etc/” and getting a bit lost. How do I restart the damned web server?! Which web server did I install? Why do I not remember how to use linux?! ARGH!!

Oh, hey. Look – I just tapped “PgUp” and saw this:

EC2 PgUp

Hello. That’s a command to see what ports are open, as far as I remember. That’s the first command from 2bitcoder‘s EC2 WordPress tutorial.

Pressing the down key resulted in listing every command I’d ever entered:

login as: ec2-user
Authenticating with public key "imported-openssh-key"
Last login: Thu Sep  8 20:27:22 2011 from blah--blah-blah-blah.blah.blah.com

       __|  __|_  )  Amazon Linux AMI
       _|  (     /     Beta
      ___|\___|___|

See /etc/image-release-notes for latest release notes. :-)
[[email protected] ~]$ apt-get install lighttpd
[[email protected] ~]$ ipkg install lighttpd
[[email protected] ~]$ yum install lighttpd
[[email protected] ~]$ sudo yum -y install lighttpd
[[email protected] ~]$ ls
[[email protected] ~]$ ls /
[[email protected] ~]$ ls /opt/
[[email protected] ~]$ ls /etc/
[[email protected] ~]$ ls /etc/httpd/
[[email protected] ~]$ ls /etc/httpd/run/
[[email protected] ~]$ sudo ls /etc/httpd/run/
[[email protected] ~]$ service httpd start
[[email protected] ~]$ httpd start
[[email protected] ~]$ sudo /etc/init.d/httpd start

I just had to hit “enter” a couple of times to replay some ancient commands to restart Apache and mysql and the site was back up and running! Phew!

So – if you’re using EC2 for hosting something and you can’t remember the very basic linux commands you fired off to get it working in the first place, fear not! PgUp is your friend!

WordPress (free) on an Amazon EC2 Micro Instance (free – for now)

This first post is about how it came to be. A bit philosophical, I know, but that’s the nature of tech sometimes..

This is a version of wordpress (free blog engine) installed in Amazon’s EC2 (Elastic Cloud Computing – or Elastic Computing Cloud – or something like that, starting with Elastic and then another two “C” words) (free). Which I think is both thrifty, and tekky geeky, and therefore pretty awesome.

Inspired by Jaimal’s post over on 2bit-coder and an email from Amazon about a free tier, I set about having a go.

The only things needed to change from Jaimal’s tutorial, are that the current free versions of the AWS Linux VM are not quite Fedora; although you do install using yum, you need to log in as “ec2-user” instead of “root”, you always have to whack a “sudo” in front of any command that needs any real privileges, and you can’t use “phpmyadmin” to set up your mysql instance for wordpress, so you have to go old skool and do it by hand.

Anyhoo. Introductions over, next up – more on random web-related tech to follow.

Semi-related references:

How to run WordPress on the NSLU2 (“hacked” router I own that I based some of the wordpress install and setup on)

Mercurial how-to (since I’ve also installed that on my EC2 instance and will follow up on that at some point)