The builder project uses SaltStack to provision Vagrant virtual machines and AWS EC2 instances.
The process for installing Salt and configuring it differs slightly depending on the platform. Vagrant instances use a masterless strategy and AWS instances use a master+minion strategy, however after the platform has been 'bootstrapped' the same instructions are used on both.
A project called salt-bootstrap is used to install Salt on both Vagrant and AWS EC2 minions. The builder script that does this is found here: ./scripts/bootstrap.sh.
For AWS EC2, the builder commands update and launch upload and execute this script. If Salt is not detected or an older version is detected, bootstrap.sh will call the salt-bootstrap script with the correct parameters.
For Vagrant, the vagrant up and vagrant provision commands will run this script.
Salt works best when both the master and clients are running on the same version of Salt, however there is backwards support for older clients talking to newer masters.
The version of Salt used is found in the defaults.salt section of your project file. When an EC2 instance is created the version of Salt to install is included in the list of build-time data, called it's context. It's this value that is passed to the bootstrap.sh script that determines whether Salt needs upgrading or not.
Before you can upgrade the version of Salt on a minion:
- update the version of Salt in your projects file
- upgrade the Salt master with
./bldr master.update_salt_master
and then:
- upgrade the minion with
./bldr master.update_salt:project--iid
Salt has been very stable with almost no problems upgrading builder instances from 2014.7 to 2015.8 to 2016.3 to 2017.8.
Grains are provided on EC2 instances and can be useful to target particular servers. Besides standard grains like osrelease (18.04) and oscodename (bionic), the following custom grains are set up during bootstrap:
projecte.g.elife-bot