Unable to set ASG instance hostnames using Troposphere/CloudFormation UserData - amazon-web-services

Question

Here's the relevant part of my Troposphere file:
LaunchConfiguration = t.add_resource(LaunchConfiguration(
"LaunchConfigA",
ImageId=UBUNTU_IMG,
SecurityGroups=[Ref(SecurityGroup)],
InstanceType="m3.medium",
UserData=Base64(Join('', [
"#cloud-boothook\n",
"#!/bin/bash\n",
"sudo hostname test\n",
"sudo sh -c 'echo test > /etc/hostname'\n",
"sudo sh -c 'echo 127.0.0.1 test >> /etc/hosts'\n",
"sudo touch /var/log/TESTING\n"
])),
))
AutoScalingGroupA = t.add_resource(AutoScalingGroup(
"GroupA",
AvailabilityZones=GetAZs(Ref(AWS_REGION)),
LaunchConfigurationName=Ref(LaunchConfiguration),
MinSize="1",
DesiredCapacity="2",
MaxSize="2",
))
When I create a brand new CloudFormation stack from this template, the hostnames on the instances look like ip-172-XXX-XXX-XXX, the default.
I am certain that the script is running, because of my TESTING file:
atrose#ip-172-31-32-40:~$ ls -la /var/log/TESTING
-rw-r--r-- 1 root root 0 Jul 14 20:10 /var/log/TESTING
If I run the script manually, the hostname is properly set. Like so:
atrose#ip-172-31-32-40:~$ hostname
ip-172-31-32-40
atrose#ip-172-31-32-40:~$ sudo cat /var/lib/cloud/instance/user-data.txt
#cloud-boothook
#!/bin/bash
sudo hostname test
sudo sh -c 'echo test > /etc/hostname'
sudo sh -c 'echo 127.0.0.1 test >> /etc/hosts'
atrose#ip-172-31-32-40:~$ sudo bash /var/lib/cloud/instance/user-data.txt
atrose#ip-172-31-32-40:~$ hostname
test
How can I set hostnames on instances when they first boot into an ASG?

Answer 1

It looks like you're using an Ubuntu AMI, which means CloudInit should have a hostname parameter built into it, and you shouldn't need a shell script to do what you want. I'm going to guess that cloudinit itself is colliding with your script. You should check this out:
http://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/view/head:/doc/examples/cloud-config.txt#L540
Let me know if you have any questions about how to use that. Thanks!