Friday, June 13, 2014

Setting up the hostname in Ubuntu

Most people recommend setting up the hostname on a Linux box so that:

1) running 'hostname' returns the short name (i.e. myhost)
2) running 'hostname -f' returns the FQDN (i.e.
3) running 'hostname -d' returns the domain name (i.e

After experimenting a bit and also finding this helpful Server Fault post, here's what we did to achieve this (we did it via Chef recipes, but it amounts to the same thing):

  • make sure we have the short name in /etc/hostname:

(also run 'hostname myhost' at the command line)
  • make sure we have the FQDN as the first entry associated with the IP of the server in /etc/hosts: myhost
  • make sure we have the domain name set up as the search domain in /etc/resolv.conf:

Reboot the box when you're done to make sure all of this survives reboots.

Modifying EC2 security groups via AWS Lambda functions

One task that comes up again and again is adding, removing or updating source CIDR blocks in various security groups in an EC2 infrastructur...