SaltStack is an open-source IT automation framework that allows administrators to execute commands remotely on multiple machines. With its Master and Minion architecture, Salt provides powerful configuration management for automation deployment, remote task execution, and infrastructure as code. In this article, we will guide you through the process of setting up SaltStack Master and Minion on Rocky Linux servers, as well as demonstrate how to run arbitrary commands, and even create a Salt state for installing a basic LEMP Stack.

Prerequisites

Before we begin, make sure you have the following prerequisites:

• Two or more Rocky Linux servers
• A non-root user with root/administrator privileges on each server

Setting Up /etc/hosts file

To start the configuration process, we need to set up the /etc/hosts file on each Linux host. In this example, we will use three Rocky Linux servers: master,minion1, and minion2. Open a terminal and run the following command to edit the /etc/hosts file:

sudo nano /etc/hosts

Add the following configuration to the file:

192.168.5.10  master
192.168.5.15  minion1
192.168.5.16  minion2

Save and close the file when you are finished.

Adding SaltStack Repository

Next, we need to add the SaltStack repository to all of your Rocky Linux servers. Run the following commands in your terminal:

sudo rpm --import https://repo.saltproject.io/py3/redhat/8/x86_64/latest/SALTSTACK-GPG-KEY.pub
curl -fsSL https://repo.saltproject.io/py3/redhat/8/x86_64/latest.repo | sudo tee /etc/yum.repos.d/salt.repo

Verify that the SaltStack repository is added to your Rocky Linux server by running the following command:

sudo dnf repolist

This command will display a list of available repositories, and you should see the SaltStack repository among them.

Installing SaltStack Master

Now that the SaltStack repository is set up, let’s proceed with installing and configuring the SaltStack Master on the master server. In your terminal, run the following command to install the salt-master package:

sudo dnf install salt-master

After the installation is complete, edit the SaltStack Master configuration file /etc/salt/master:

sudo nano /etc/salt/master

Uncomment the interface: option and replace the IP address with the IP address of your master server. Save and close the file.

To enable the salt-master service to run at system boot and start the service, run the following commands:

sudo systemctl enable salt-master
sudo systemctl start salt-master

You can verify the status of the salt-master service by running:

sudo systemctl status salt-master

To allow SaltStack Minions to connect to the SaltStack Master, open TCP ports 4505 and 4506 on your firewall. Run the following commands:

sudo firewall-cmd --zone=public --permanent --add-port=4505/tcp
sudo firewall-cmd --zone=public --permanent --add-port=4506/tcp
sudo firewall-cmd --reload

Verify that the ports are open by running:

sudo firewall-cmd --list-all
Installing SaltStack Minion

With the SaltStack Master set up, we can now proceed to install and configure the SaltStack Minion on the minion1 and minion2 servers. Connect to each server and run the following command to install the salt-minion package:

sudo dnf install salt-minion

After the installation is complete, edit the SaltStack Minion configuration file /etc/salt/minion:

sudo nano /etc/salt/minion

Uncomment the master: option and replace the IP address with the IP address of your master server. Save and close the file.

To enable the salt-minion service to run at system boot and start the service, run the following commands:

sudo systemctl enable salt-minion
sudo systemctl start salt-minion

You can verify the status of the salt-minion service by running:

sudo systemctl status salt-minion

Adding Minion Servers to SaltStack Master

Now that both the SaltStack Master and Minion are installed, we need to add the Minion servers to the SaltStack Master. On the master server, run the following command to check all available key fingerprints:

salt-key --finger-all

You should see the fingerprints of the minion1 and minion2 servers listed as “Unaccepted Keys”. To accept the key fingerprints, run the following commands:

salt-key -a minion1
salt-key -a minion2

To verify that the key fingerprints are accepted, run the following command:

salt-key --finger-all

You should now see the fingerprints of the minion1 and minion2 servers listed as “Accepted Keys”.

To test the connection between the SaltStack Master and the Minion servers, run the following command on the master server:

salt minion1 test.ping
salt minion2 test.ping

If the configuration is successful, you should see the output message “True”, indicating that the SaltStack Minion servers are connected to the SaltStack Master.

Running Arbitrary Commands with SaltStack

One of the powerful features of SaltStack is the ability to run arbitrary commands from the SaltStack Master to the Minion servers. To demonstrate this, we will use the cmd module provided by Saltstack.

On the master server, run the following command to execute the uname -a command on all Minion servers:

salt '*' cmd.run 'uname -a'

This command will display the output of the uname -a command for each Minion server.

SaltStack also provides modules for managing package installation, repositories, services, and more. For example, you can use the pkg module to manage packages on multiple Linux distributions. Run the following commands to perform package-related tasks on all Minion servers:

salt '*' pkg.refresh_db
salt '*' pkg.show bash
salt '*' pkg.install chrony
salt '*' pkg.list_repos
salt '*' pkg.list_upgrades

These commands will refresh the package repositories, check the details of the bash package, install the chrony package, list the available repositories, and check for available package upgrades.

You can also use the service module to manage services on multiple Linux distributions. For example, to check the availability of the chronyd service, enable it to start at system boot, and check the list of running services, run the following commands:

salt '*' service.available chronyd
salt '*' service.enabled chronyd
salt '*' service.get_running
salt '*' service.execs

These commands will help you manage services on your Minion servers.

Installing LEMP Stack with SaltStack State

SaltStack can also be used as a configuration management tool to automate the installation and setup of applications. In this section, we will create a SaltStack state file to install a basic LEMP Stack (Linux, Nginx, MariaDB, and PHP-FPM) on the Minion servers.

First, create a central configuration management directory /srv/salt/lemp and a new file init.sls using the following commands:

sudo mkdir -p /srv/salt/lemp
sudo nano /srv/salt/lemp/init.sls

Add the following configuration to the file:

lemp_stack:
pkg.installed:
- pkgs:
- nginx
- mariadb-server
- php
- php-fpm

nginx:
service.running:
- enable: True
- reload: True

mariadb:
service.running:
- enable: True
- reload: True

php-fpm:
service.running:
- enable: True
- reload: True

Save and close the file.

To verify the Salt state configuration, run the following command:

sudo salt '*' state.show_sls lemp

This command will display the Salt state configuration for installing the LEMP Stack.

To apply the Salt state to the Minion servers and automatically install the LEMP Stack, run the following command:

sudo salt '*' state.apply lemp

You will see the installation progress and confirmation messages for each package.

Conclusion

Congratulations! You have successfully installed and configured SaltStack Master and Minion on your Rocky Linux servers. You have learned how to run arbitrary commands from the SaltStack Master to the Minion servers, as well as how to create a Salt state for installing the LEMP Stack. SaltStack provides a powerful and flexible configuration management solution for automating your infrastructure and application deployments.

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