rob's Weblog

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 $ pipeline blogposts:all task:blogpost2html concat:-

Emulate EC2's 169.254.169.254 for your own VMs

Assuming you have your bridge configured as br0, and are are running a webserver on port 9880 (either unbound or bound the primary IP of the bridge ‘br0’), the following should allow a KVM VM, LXC container, etc. to connect to http://169.254.169.254/ just like they can in Amazon EC2. This has to be run on the server hosting the VMs, of course.

# sysctl net.bridge.bridge-nf-call-iptables=1 
# sysctl net.bridge.bridge-nf-call-arptables=1
# ip addr add 169.254.169.254/32 dev br0 
# iptables -t nat -A PREROUTING -d 169.254.169.254 -p tcp --dport 80 -j REDIRECT --to-port 9880
or using DNAT:
# ip addr add 169.254.169.254/32 dev lo
# iptables -t nat -A PREROUTING -j DNAT -d 169.254.169.254 -p tcp --dport 80 --to 169.254.169.254:9880

Your webserver should probably ensure that the request is coming from the IP of one of the VMs currently running on the server itself.

— by Robert Thomson, created 14th Feb, 2014, last modified 14th Feb, 2014 | Tags: Tech

Packer.io

I love software that "just works", and packer.io is one of them. It builds disk images in various image formats and for various cloud providers.

With a small JSON configuration file, a kickstart file, and a set of provisioning scripts, I can have a QEMU image automatically built from the install CD and customised as I wish.

With a different config file, I can have the same thing for EC2 images.

And because it's JSON, I can dynamically generate custom configuration files quickly and easily.

There seems to be a positive trend of self-contained, single-purpose and well designed software coming from the Golang camp. Keep at it! :-)

— by Robert Thomson, created 9th Jan, 2014, last modified 9th Jan, 2014 | Tags: Tech

SaltStack

Following up from my post about Ansible, I decided to look into SaltStack.

SaltStack looks like one of the more promising tools to appear recently on the system management landscape.

It's primary features are:

This is an impressive set of features for a single solution, but there are some areas of concern:

Some specific technical issues appear to be:

I hold out hope that these issues will be addressed. In the meantime, I won't be recommending it as a general purpose solution for a large organisation.

— by Robert Thomson, created 15th Oct, 2013, last modified 15th Oct, 2013 | Tags: Tech

Skully

I bought a skull... then I painted it...

My new skull

I expect he'll be drawn/painted many more times over the years.. but this painting is the first. :-)

— by Rob, created 15th Sep, 2013, last modified 15th Sep, 2013 | Tags: Private

Off to Australia

Sophia and I will be in Australia until the start of June. It's just a quick trip this time to catch up with family and friends.

Update: We're back from Australia. It was fun!

— by Robert Thomson, created 9th May, 2013, last modified 4th Jun, 2013 | Tags: Private
... now get off my lawn!