Table of Contents
Sourdough
Sourdough is a tool to install chef-client during instance boot, or to run chef-client after boot.
Sourdough reads the Environment and Runlist EC2 / VMware tags and runs chef-client with those settings so you can update an instance's Chef settings just by tweaking its tags. This also lets you see what runlist and environment an instance has using just the AWS/VMware webui, so no more having to correlate Chef information for your instances in two places.
Testing
Pre-requisites
You must have docker and docker-compose installed on your machine to run the test suite.
How to run the tests
make test will build a container, then run the tests inside the container with docker-compose.
WARNING only run the tests inside a disposable container - they will destroy the chef installation on your machine.
FAQs
How are node names generated?
EC2
If we're in EC2, we look for a Node tag/knob. If a Node tag or knob exists, our node name will be AWS_REGION-NODE_TAG_KNOB-INSTANCE_ID
If the node tag and knob don't exist, we look for a Hostname tag or knob and set the node name to AWS_REGION-HOSTNAME_TAGKNOB.
If the Hostname tag or knob are both missing we fail back to reading the output of hostname which is better than nothing.
Outside EC2
If we aren't in EC2, we look for a /etc/knobs/Hostname file and use the
contents of that - if there's no knob file we use the output of
hostname so we have at least something sane-ish.
How is the runlist determined?
EC2 / VMware
First we attempt to read the instance's Runlist tag and set the runlist to that. If we can't reach AWS/vSphere to read a tag, we search for /etc/knobs/Runlist and use the contents of that. If we still haven't found a Runlist setting we look for a default_runlist entry in /etc/sourdough/sourdough.toml. Once we determine a Runlist, we write it to /etc/knobs/Runlist to use as a fallback on future runs.
What Chef environment does Sourdough use
Similarly to how it determines the Runlist, sourdough looks for an Environment tag for the instance, and if that is missing, looks for /etc/knobs/Environment, and finally falls back to looking for a default_environment entry in /etc/sourdough/sourdough.toml
How do I have sourdough pass environment variables to chef-client?
sourdough will look for /etc/sourdough/environment-variables.json, and if present and valid JSON, will pass the variables inside to chef-client when it runs it.
VMware Vcenter configuration
sourdough will look for /etc/sourdough/vmware.toml, and if present and valid toml, it will search for the UUID of the VM in the vSphere host(s) listed there. Check the example_vmware.toml file for configuration details.
