This document provides a step-by-step guide to installing a Salt cluster consisting of one master, and one minion running on a local VM hosted on macOS.
This guide is aimed at developers who wish to run Salt in a virtual machine. The official (Linux) walkthrough can be found here.
Since you're here you've probably already heard about Salt, so you already know Salt lets you configure and run commands on hordes of servers easily. Here's a brief overview of a Salt cluster:
Salt works by having a "master" server sending commands to one or multiple "minion" servers. The master server is the "command center". It is going to be the place where you store your configuration files, aka: "which server is the db, which is the web server, and what libraries and software they should have installed". The minions receive orders from the master. Minions are the servers actually performing work for your business.
Salt has two types of configuration files:
1. the "salt communication channels" or "meta" or "config" configuration files (not official names): one for the master (usually is /etc/salt/master , on the master server), and one for minions (default is /etc/salt/minion or /etc/salt/minion.conf, on the minion servers). Those files are used to determine things like the Salt Master IP, port, Salt folder locations, etc.. If these are configured incorrectly, your minions will probably be unable to receive orders from the master, or the master will not know which software a given minion should install.
2. the "business" or "service" configuration files (once again, not an official name): these are configuration files, ending with ".sls" extension, that describe which software should run on which server, along with particular configuration properties for the software that is being installed. These files should be created in the /srv/salt folder by default, but their location can be changed using ... /etc/salt/master configuration file!
This tutorial contains a third important configuration file, not to be confused with the previous two: the virtual machine provisioning configuration file. This in itself is not specifically tied to Salt, but it also contains some Salt configuration. More on that in step 3. Also note that all configuration files are YAML files. So indentation matters.
Salt also works with "masterless" configuration where a minion is autonomous (in which case salt can be seen as a local configuration tool), or in "multiple master" configuration. See the documentation for more on that.
The "Salt master" server is going to be the Mac OS machine, directly. Commands will be run from a terminal app, so Salt will need to be installed on the Mac. This is going to be more convenient for toying around with configuration files.
We'll only have one "Salt minion" server. It is going to be running on a Virtual Machine running on the Mac, using VirtualBox. It will run an Ubuntu distribution.
Because Salt has a lot of dependencies that are not built in macOS, we will use Homebrew to install Salt. Homebrew is a package manager for Mac, it's great, use it (for this tutorial at least!). Some people spend a lot of time installing libs by hand to better understand dependencies, and then realize how useful a package manager is once they're configuring a brand new machine and have to do it all over again. It also lets you uninstall things easily.
Brew is a Ruby program (Ruby is installed by default with your Mac). Brew
downloads, compiles, and links software. The linking phase is when compiled
software is deployed on your machine. It may conflict with manually
installed software, especially in the /usr/local directory. It's ok,
remove the manually installed version then refresh the link by typing
brew link 'packageName'. Brew has a
brew doctor command that can
help you troubleshoot. It's a great command, use it often. Brew requires
xcode command line tools. When you run brew the first time it asks you to
install them if they're not already on your system. Brew installs
software in /usr/local/bin (system bins are in /usr/bin). In order to use
those bins you need your $PATH to search there first. Brew tells you if
your $PATH needs to be fixed.
Use the keyboard shortcut
cmd + shift + period in the "open" macOS
dialog box to display hidden files and folders, such as .profile.
Install Homebrew here https://brew.sh/
Or just type
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Now type the following commands in your terminal (you may want to type
doctor after each to make sure everything's fine):
brew install python brew install swig brew install zmq
zmq is ZeroMQ. It's a fantastic library used for server to server network communication and is at the core of Salt efficiency.
You should now have everything ready to launch this command:
pip install salt
There should be no need for
sudo pip install salt. Brew installed
Python for your user, so you should have all the access. In case you
would like to check, type
which python to ensure that it's
which pip which should be
python in a terminal then,
import salt. There should be no
errors. Now exit the Python terminal using
If the default /etc/salt/master configuration file was not created, copy-paste it from here: https://docs.saltproject.io/ref/configuration/examples.html#configuration-examples-master
/etc/salt/master is a file, not a folder.
Salt Master configuration changes. The Salt master needs a few customization to be able to run on macOS:
sudo launchctl limit maxfiles 4096 8192
In the /etc/salt/master file, change max_open_files to 8192 (or just add the
max_open_files: 8192 (no quote) if it doesn't already exists).
You should now be able to launch the Salt master:
sudo salt-master --log-level=all
There should be no errors when running the above command.
This command is supposed to be a daemon, but for toying around, we'll keep it running on a terminal to monitor the activity.
Now that the master is set, let's configure a minion on a VM.
The Salt minion is going to run on a Virtual Machine. There are a lot of software options that let you run virtual machines on a mac, But for this tutorial we're going to use VirtualBox. In addition to virtualBox, we will use Vagrant, which allows you to create the base VM configuration.
Vagrant lets you build ready to use VM images, starting from an OS image and customizing it using "provisioners". In our case, we'll use it to:
Download the base Ubuntu image
Install salt on that Ubuntu image (Salt is going to be the "provisioner" for the VM).
Launch the VM
SSH into the VM to debug
Stop the VM once you're done.
Go get it here: https://www.virtualbox.org/wiki/Downloads (click on VirtualBox for macOS hosts => x86/amd64)
Go get it here: https://www.vagrantup.com/downloads.html and choose the latest version
(1.3.5 at time of writing), then the .dmg file. Double-click to install it.
Make sure the
vagrant command is found when run in the terminal. Type
vagrant. It should display a list of commands.
Create a folder in which you will store your minion's VM. In this tutorial, it's going to be a minion folder in the $home directory.
cd $home mkdir minion
From the minion folder, type
This command creates a default Vagrantfile configuration file. This configuration file will be used to pass configuration parameters to the Salt provisioner in Step 3.
vagrant box add precise64 http://files.vagrantup.com/precise64.box
This box is added at the global Vagrant level. You only need to do it once as each VM will use this same file.
Modify ./minion/Vagrantfile to use th precise64 box. Change the
config.vm.box = "precise64"
Uncomment the line creating a host-only IP. This is the ip of your minion (you can change it to something else if that IP is already in use):
config.vm.network :private_network, ip: "192.168.33.10"
At this point you should have a VM that can run, although there won't be much in it. Let's check that.
From the $home/minion folder type:
A log showing the VM booting should be present. Once it's done you'll be back to the terminal:
The VM should respond to your ping request.
Now log into the VM in ssh using Vagrant again:
You should see the shell prompt change to something similar to
vagrant@precise64:~$ meaning you're inside the VM. From there, enter the
That ip is the ip of your VM host (the macOS host). The number is a
VirtualBox default and is displayed in the log after the Vagrant ssh
command. We'll use that IP to tell the minion where the Salt master is.
Once you're done, end the ssh session by typing
It's now time to connect the VM to the salt master
/etc/salt/minion file. In that file, put the
following lines, giving the ID for this minion, and the IP of the master:
master: 10.0.2.2 id: 'minion1' file_client: remote
Minions authenticate with the master using keys. Keys are generated automatically if you don't provide one and can accept them later on. However, this requires accepting the minion key every time the minion is destroyed or created (which could be quite often). A better way is to create those keys in advance, feed them to the minion, and authorize them once.
From the minion folder on your Mac run:
sudo salt-key --gen-keys=minion1
This should create two files: minion1.pem, and minion1.pub. Since those files have been created using sudo, but will be used by vagrant, you need to change ownership:
sudo chown youruser:yourgroup minion1.pem sudo chown youruser:yourgroup minion1.pub
Then copy the .pub file into the list of accepted minions:
sudo cp minion1.pub /etc/salt/pki/master/minions/minion1
Let's now modify the Vagrantfile used to provision the Salt VM. Add the following section in the Vagrantfile (note: it should be at the same indentation level as the other properties):
# salt-vagrant config config.vm.provision :salt do |salt| salt.run_highstate = true salt.minion_config = "/etc/salt/minion" salt.minion_key = "./minion1.pem" salt.minion_pub = "./minion1.pub" end
Now destroy the vm and recreate it from the /minion folder:
vagrant destroy vagrant up
If everything is fine you should see the following message:
"Bootstrapping Salt... (this may take a while) Salt successfully configured and installed!"
To make sure the master and minion are talking to each other, enter the following:
sudo salt '*' test.version
You should see your minion answering with its salt version. It's now time to do some configuration.
In this step we'll use the Salt master to instruct our minion to install Nginx.
First, make sure that an HTTP server is not installed on our minion.
When opening a browser directed at
http://192.168.33.10/ You should get an
error saying the site cannot be reached.
System configuration is done in
/srv/salt/top.sls (and subfiles/folders),
and then applied by running the
state.apply function to have the Salt master order its minions
to update their instructions and run the associated commands.
First Create an empty file on your Salt master (macOS machine):
When the file is empty, or if no configuration is found for our minion an error is reported:
sudo salt 'minion1' state.apply
This should return an error stating: No Top file or external nodes data matches found.
Now is finally the time to enter the real meat of our server's configuration. For this tutorial our minion will be treated as a web server that needs to have Nginx installed.
Insert the following lines into
/srv/salt/top.sls (which should current be
base: 'minion1': - bin.nginx
/srv/salt/bin/nginx.sls containing the following:
nginx: pkg.installed: - name: nginx service.running: - enable: True - reload: True
Finally, run the
sudo salt 'minion1' state.apply
You should see a log showing that the Nginx package has been installed and the service configured. To prove it, open your browser and navigate to http://192.168.33.10/, you should see the standard Nginx welcome page.
A full description of configuration management within Salt (sls files among other things) is available here: https://docs.saltproject.io/en/latest/index.html#configuration-management