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SaltStack

What is Configuration mangement?

  • Configuration mangement is the practace of centrally managing and configuring systems from a centralized control point. Configuration management tools are used for remote configuration of systems (Windows or Linux) in an environment.

Configration Management tools

  • Ansible

  • Puppet

  • Chef

  • SaltStack

About Salt

  • Started in 2011 by Thomas Hatch

  • Python based, and open source

  • Uses the YAML data structure along with JINJA templating

  • It has a large open source community

  • It uses a client-server model, allowing for remote command execution

  • Easily scalable, supporting thousands of nodes

  • Uses message queue networking

  • Highly modular

Architecture

  • Client-server model

    • Master (server)
    • Minion (client)

  • Uses the asynchronous message library ZeroMQ for message queuing

  • Communication encrypted over SSH

Salt Architecture

Pillars and Grains

  • Pillars

    • User defined variables that are stored on the minion

      • Also able to be stored on a git server

  • Grains

    • Static information, such as OS version, about a device (minion)

Execution Modules

  • Add hoc commands on the command line targeting one or more minions

Salt Execution Modules

States

  • Each salt state is contained in an Salt State File (SLS)

  • These state files are written in YAML, and can also contain JINJA templates

network_utilities:
  pkg.installed:
    - pkgs:
      - rsync
      - curl

nginx_pkg:
  pkg.installed:
    - name: nginx

nginx_service:
  service.running:
    - name: nginx
    - enable: True
    - require:
      - pkg: nginx_pkg

Top File

  • There are two top files that exist

    1. The states top file maps the machines and the states that should be applied to them
    2. The pillars top file maps the machines and the pillar data that they can access
base:
    # Applied to all servers
    '*':
        - universal_setp
    # Applied only to ubuntu servers
    'os:Ubuntu':
        - match: grain
        - ubuntu_setup
    # Applied only to web-server
    web-server:
        - apache_setup

Targeting Minions

  • We can target minions using a list, regex, grains, or node groups
salt minion1 test.ping
salt "minion*" test.ping
salt -L "minion1, minion2" test.ping
Salt -G 'os_family:windows' test.ping
salt -N windows_minions test.ping
  • node groups, configured in master configuration (/etc/salt/master)
nodegroups:
    windows_minions 'G@os_family:windows'

Event System

  • uses publisher/subscribe model for publishing events

  • Events are published onto the event bus and event bus subscribers listen for the published events.

# Watch the event bus forever in a shell while-loop.
salt-run state.event | while read -r tag data; do
    echo $tag
    echo $data | jq --color-output .
done

Reactor

  • Allows for taking actions related to events by watching the event bus for event tags that match a given pattern and then running one or more commands in response

Salt Installation (Ubuntu Example)

  1. Run the following command to import the SaltStack repository key:
wget -O - <https://repo.saltstack.com/apt/ubuntu/18.04/amd64/latest/SALTSTACK-GPG-KEY.pub> | sudo apt-key add -
  1. Save the following file to /etc/apt/sources.list.d/saltstack.list:
deb http://repo.saltstack.com/apt/ubuntu/18.04/amd64/latest bionic main

  1. Run sudo apt-get update

  2. Install the salt-minion, salt-master, or other Salt components:

sudo apt-get install salt-master
sudo apt-get install salt-minion

Once installed all Salt components are controlled through systemd unit files

Salt master Configuration

  • location:

    • /etc/salt/master (default)
    • /etc/salt/master.d/*.conf (atomic configuration files)

  • contains:

    • File server settings (i.e. git configuration)
    • nodegroups
    • mysql connection
    • reactor states

Salt Minion Configuration

  • location:

    • /etc/salt/minion

  • contains

    • master location value
    • logging level