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I want to emulate the Amazon EC2 metadata service on my local system for testing. In EC2, this runs on 169.254.169.254. I understand that this is the designated range for pseudorandom local addresses on DHCP failure, but Amazon in their wisdom are also using it for this purpose, so I need to do the same thing.

I'm using F19 Alpha. In earlier Fedora, I could simply make a virtual interface on the loopback device, like lo:0 and assign that a static address using the normal ifcfg- scripts. Now, that fails with "Error: Connection activation failed: Device not managed by NetworkManager or unavailable".

(I'm running NetworkManager, but previously I was doing this underneath it.)

Is finding some way to continue what I was doing with lo:0 the right approach (and if so, how?), or is there a better way?

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  • Couldn't you do this with netfilter/iptables? Like NAT back to 127.0.0.1? – goldilocks Apr 26 '13 at 20:26
  • @goldilocks why fake it when you can do it for real? ;) – Tim Apr 26 '13 at 20:59
7

To answer your specific question, you can use iproute2 to assign the IP address like this:

sudo ip addr add 169.254.169.254/8 dev lo

It will just add a new IP to the interface, no need for aliasing with :0, :1, etc. Note this is going to be lost after a reboot.

And to quickly emulate the metadata service you can use netcat like this:

while true; do sudo nc -l 169.254.169.254 80 <<< '"region" : "eu-west-1"'; test $? != 0 && break; done

This will give you the region when asking like this:

curl -s http://169.254.169.254/latest/dynamic/instance-identity/document
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2

Haven't used Fedora in a while, but it should still be very similar to CentOS. I did this on CentOS 6.

Copy /etc/sysconfig/network-scripts/ifcfg-lo to /etc/sysconfig/network-scripts/ifcfg-lo:1

Your new config should look like so:

DEVICE=lo:1
IPADDR=169.254.169.254
NETMASK=255.0.0.0
ONBOOT=yes
NAME=loopback1

Restart the network service service network restart.

Bonne chance mon ami !

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  • Unfortunately, this is exactly what I was doing and what was working but now isn't. – mattdm Apr 28 '13 at 14:32
  • As I said above, shouldn't this be a /16 network (so, netmask 255.255.0.0)? – Tom Hundt Oct 1 at 22:03

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