Using Salt

Introduction to SaltStack, a Linux configuration management tool.

What is Salt?

Salt, also called SaltStack, is an open-source configuration managment and automation tool. It allows system administrators to:

  • Define system states (e.g. install packages, run services, configure users, etc.)

  • Apply those configurations across multiple machines consistently

  • Automate routine infrastructure tasks like updates, configuration changes, or user provisioning

Salt follows a master-minion architecture, where:

  • The Salt master sends commands and configurations

  • The Salt minion executes those commands

A deeper introduction to Salt can be found here.

Installing Salt

The Salt Project documentation offers a quick installation guide for Linux based operating systems. If you are running RHEL-like systems, follow the Linux (RPM) Install Guide. If you are running Debian-like systems, follow the Linux (DEB) Install Guide. Each guide includes post-installation steps for configuring the Salt master and minions, starting the master and minion services, accepting the minion keys, and verifying your Salt installation.

Understanding Salt

As previously mentioned, Salt is a powerful open-source tool for automating system configuration, remote execution, and infrastructure management. It uses a master/minion model where the master controls and sends instructions and the minion receives and applies configurations. There are several key concepts that will be important to know when working with Salt.

Key Concepts

Concept

Description

State

A YAML file that describes the desired configuration of a system.

Grains

Static system facts collected by the minion (like OS, IP, CPU type). Can be used to target systems based on their characteristics.

Pillar

Secure targeted data defined on the master and passed to the minions. Used for secrets, config values, or variables in state files.

Top File

A special file top.sls that tells Salt which states to apply to which minions. It acts as the entry point for configuration.

Highstate

The process of applying all states defined in the top file to the appropriate minions.

Formulas

Reusable Salt state modules that configure common components (like users or services).

Common Salt Commands

Command

Description

salt '*' test.ping

Ping all minions

salt '*' grains.item host

Get minion hostname

salt '*' grains.item

Get full grain info

salt '*' grains.item os osrelease

Get OS details

salt '*' cmd.run 'uptime'

Run a shell command on minions

salt '*' state.apply myfile

Apply a file to a state

salt '*' state.apply

Run highstate

Using Vagrant as a Development Environment (optional)

Vagrant is a tool for managing virtual machine environments in a reproducible way using simple configuration files called Vagrantfile. Vagrant makes it easy to rebuild development environments, which is great for testing Salt states before applying them in production. Vagrant is also compatible with KVM environments. Learn more about using Vagrant with your KVM / Libvirt environment here.

Resources