SaltStack Crash Course

What is SaltStack?

SaltStack is a configuration management tool.
It allows you to manage thousands of servers (or just one) from a central location.

This post will help you getting started with several VMs you can use to get to know SaltStack. After you’ve followed these instructions, you will get one Salt Master and 2 Salt Minions on which you can execute your commands.

Prerequisites

Getting Started

git clone https://github.com/Oro/salt-crashcourse.git
cd salt-crashcourse
vagrant up

The first time you execute vagrant up it might take several minutes, depending on your internet connection. Subsequent executions will be much faster since the boxes will be cached on your local machine.
After the VMs started successfully, you can connect to the Salt master via

vagrant ssh master

Salt commands on this machine require sudo permissions, so switch to root via

sudo su

Now you can execute salt commands. Let’s try an execution module, test.ping on all VMs:

salt '*' test.ping

SaltStack can issue commands two different ways, via execution modules and via state modules. Modules can be called for any machine via the Salt master, or for the local machine via salt-call.

Salt CLI

salt '*' test.ping
\__/ \_/ \_______/
  |   |      |
  |   |      \- The execution module to run
  |   |
  |   \- The minions to target (do not forget to enclose an asterisk
  |      with quotes)
  |
  \- The salt command itself

1

Salt State Modules

SaltStack files are written (per default) in YAML.
The top.sls for state modules consists of 3 elements and is used to target specific minions with specific states.

# salt/roots/top.sls
base:                      # Environment
  '*':                     # Target
    - my_own_git_state     # State

A state consists of an ID (that is unique across all state modules), the module to execute and its parameters.

# salt/roots/my_own_git_state.sls
my_own_git_state:          # Unique ID
  pkg.installed:           # State Module
    - name: git            # Parameter

With 2 files (top.sls and my_own_git_state.sls) inside salt/roots/ you can now go ahead and execute

salt '*' state.apply 

This will now make sure that git is installed on all 3 machines. On the master git is already installed, hence SaltStack will not change anything. On the two minions however git alongside its dependencies will be installed via apt-get. Now imagine you do not only want git, but also a git repository cloned. This can be easily done by appending the git.latest state module to our state file so that it looks as follows:

my_own_git_state:          # Unique ID
  pkg.installed:           # State Module
    - name: git            # Parameter
  git.latest:
    - name: https://github.com/Oro/salt-crashcourse.git 
    - target: /srv/crashcourse

And now let’s again apply the state to all VMs:

salt '*' state.apply 

Further Reading

If you want to know more, I recommend the excellent SaltStack Tutorials, which goes far more in-depth.


  1. Generated with explain [return]