# Salt in 10 Minutes

Note

Welcome to Salt Project! I am excited that you are interested in Salt and starting down the path to better infrastructure management. I developed (and am continuing to develop) Salt with the goal of making the best software available to manage computers of almost any kind. I hope you enjoy working with Salt and that the software can solve your real world needs!

- Thomas S Hatch

- Salt Project creator and Chief Developer of Salt Project

## Getting Started

### What is Salt?

Salt is a different approach to infrastructure management, founded on the idea that high-speed communication with large numbers of systems can open up new capabilities. This approach makes Salt a powerful multitasking system that can solve many specific problems in an infrastructure.

The backbone of Salt is the remote execution engine, which creates a high-speed, secure and bi-directional communication net for groups of systems. On top of this communication system, Salt provides an extremely fast, flexible, and easy-to-use configuration management system called `Salt States`.

### Installing Salt

SaltStack has been made to be very easy to install and get started. The Salt install guide provides instructions for all supported platforms.

### Starting Salt

Salt functions on a master/minion topology. A master server acts as a central control bus for the clients, which are called `minions`. The minions connect back to the master.

#### Setting Up the Salt Master

Turning on the Salt Master is easy -- just turn it on! The default configuration is suitable for the vast majority of installations. The Salt Master can be controlled by the local Linux/Unix service manager:

On Systemd based platforms (newer Debian, openSUSE, Fedora):

    systemctl start salt-master

On Upstart based systems (Ubuntu, older Fedora/RHEL):

    service salt-master start

On SysV Init systems (Gentoo, older Debian etc.):

    /etc/init.d/salt-master start

Alternatively, the Master can be started directly on the command-line:

    salt-master -d

The Salt Master can also be started in the foreground in debug mode, thus greatly increasing the command output:

    salt-master -l debug

The Salt Master needs to bind to two TCP network ports on the system. These ports are `4505` and `4506`. For more in depth information on firewalling these ports, the firewall tutorial is available here.

#### Finding the Salt Master

When a minion starts, by default it searches for a system that resolves to the `salt` hostname on the network. If found, the minion initiates the handshake and key authentication process with the Salt master. This means that the easiest configuration approach is to set internal DNS to resolve the name `salt` back to the Salt Master IP.

Otherwise, the minion configuration file will need to be edited so that the configuration option `master` points to the DNS name or the IP of the Salt Master:

Note

The default location of the configuration files is `/etc/salt`. Most platforms adhere to this convention, but platforms such as FreeBSD and Microsoft Windows place this file in different locations.

`/etc/salt/minion:`

    master: saltmaster.example.com

#### Setting up a Salt Minion

Note

The Salt Minion can operate with or without a Salt Master. This walk-through assumes that the minion will be connected to the master, for information on how to run a master-less minion please see the master-less quick-start guide:

Masterless Minion Quickstart

Now that the master can be found, start the minion in the same way as the master; with the platform init system or via the command line directly:

As a daemon:

    salt-minion -d

In the foreground in debug mode:

    salt-minion -l debug

When the minion is started, it will generate an `id` value, unless it has been generated on a previous run and cached (in `/etc/salt/minion_id` by default). This is the name by which the minion will attempt to authenticate to the master. The following steps are attempted, in order to try to find a value that is not `localhost`:

1. The Python function `socket.getfqdn()` is run

2. `/etc/hostname` is checked (non-Windows only)

3. `/etc/hosts` (`%WINDIR%\system32\drivers\etc\hosts` on Windows hosts) is checked for hostnames that map to anything within 127.0.0.0/8.

If none of the above are able to produce an id which is not `localhost`, then a sorted list of IP addresses on the minion (excluding any within 127.0.0.0/8) is inspected. The first publicly-routable IP address is used, if there is one. Otherwise, the first privately-routable IP address is used.

If all else fails, then `localhost` is used as a fallback.

Note

Overriding the `id`

The minion id can be manually specified using the `id` parameter in the minion config file. If this configuration value is specified, it will override all other sources for the `id`.

Now that the minion is started, it will generate cryptographic keys and attempt to connect to the master. The next step is to venture back to the master server and accept the new minion's public key.

#### Using salt-key

Salt authenticates minions using public-key encryption and authentication. For a minion to start accepting commands from the master, the minion keys need to be accepted by the master.

The `salt-key` command is used to manage all of the keys on the master. To list the keys that are on the master:

    salt-key -L

The keys that have been rejected, accepted, and pending acceptance are listed. The easiest way to accept the minion key is to accept all pending keys:

    salt-key -A

Note

Keys should be verified! Print the master key fingerprint by running `salt-key -F master` on the Salt master. Copy the `master.pub` fingerprint from the Local Keys section, and then set this value as the `master_finger` in the minion configuration file. Restart the Salt minion.

On the master, run `salt-key -f minion-id` to print the fingerprint of the minion's public key that was received by the master. On the minion, run `salt-call key.finger --local` to print the fingerprint of the minion key.

On the master:

    # salt-key -f foo.domain.com
    Unaccepted Keys:
    foo.domain.com:  39:f9:e4:8a:aa:74:8d:52:1a:ec:92:03:82:09:c8:f9

On the minion:

    # salt-call key.finger --local
    local:
        39:f9:e4:8a:aa:74:8d:52:1a:ec:92:03:82:09:c8:f9

If they match, approve the key with `salt-key -a foo.domain.com`.

#### Sending the First Commands

Now that the minion is connected to the master and authenticated, the master can start to command the minion.

Salt commands allow for a vast set of functions to be executed and for specific minions and groups of minions to be targeted for execution.

The `salt` command is comprised of command options, target specification, the function to execute, and arguments to the function.

A simple command to start with looks like this:

    salt '*' test.version

The `*` is the target, which specifies all minions.

`test.version` tells the minion to run the `test.version` function.

In the case of `test.version`, `test` refers to a execution module. `version` refers to the `version` function contained in the aforementioned `test` module.

Note

Execution modules are the workhorses of Salt. They do the work on the system to perform various tasks, such as manipulating files and restarting services.

The result of running this command will be the master instructing all of the minions to execute `test.version` in parallel and return the result. Using `test.version` is a good way of confirming that a minion is connected, and reaffirm to the user the salt version(s) they have installed on the minions.

Note

Each minion registers itself with a unique minion ID. This ID defaults to the minion's hostname, but can be explicitly defined in the minion config as well by using the `id` parameter.

Of course, there are hundreds of other modules that can be called just as `test.version` can. For example, the following would return disk usage on all targeted minions:

    salt '*' disk.usage

#### Getting to Know the Functions

Salt comes with a vast library of functions available for execution, and Salt functions are self-documenting. To see what functions are available on the minions execute the `sys.doc` function:

    salt '*' sys.doc

This will display a very large list of available functions and documentation on them.

Note

Module documentation is also available on the web.

These functions cover everything from shelling out to package management to manipulating database servers. They comprise a powerful system management API which is the backbone to Salt configuration management and many other aspects of Salt.

Note

Salt comes with many plugin systems. The functions that are available via the `salt` command are called Execution Modules.

#### Helpful Functions to Know

The `cmd` module contains functions to shell out on minions, such as `cmd.run` and `cmd.run_all`:

    salt '*' cmd.run 'ls -l /etc'

The `pkg` functions automatically map local system package managers to the same salt functions. This means that `pkg.install` will install packages via `yum` on Red Hat based systems, `apt` on Debian systems, etc.:

    salt '*' pkg.install vim

Note

Some custom Linux spins and derivatives of other distributions are not properly detected by Salt. If the above command returns an error message saying that `pkg.install` is not available, then you may need to override the pkg provider. This process is explained here.

The `network.interfaces` function will list all interfaces on a minion, along with their IP addresses, netmasks, MAC addresses, etc:

    salt '*' network.interfaces

#### Changing the Output Format

The default output format used for most Salt commands is called the `nested` outputter, but there are several other outputters that can be used to change the way the output is displayed. For instance, the `pprint` outputter can be used to display the return data using Python's `pprint` module:

    root@saltmaster:~# salt myminion grains.item pythonpath --out=pprint
    {'myminion': {'pythonpath': ['/usr/lib64/python2.7',
                                 '/usr/lib/python2.7/plat-linux2',
                                 '/usr/lib64/python2.7/lib-tk',
                                 '/usr/lib/python2.7/lib-tk',
                                 '/usr/lib/python2.7/site-packages',
                                 '/usr/lib/python2.7/site-packages/gst-0.10',
                                 '/usr/lib/python2.7/site-packages/gtk-2.0']}}

The full list of Salt outputters, as well as example output, can be found here.

#### `salt-call`

The examples so far have described running commands from the Master using the `salt` command, but when troubleshooting it can be more beneficial to login to the minion directly and use `salt-call`.

Doing so allows you to see the minion log messages specific to the command you are running (which are not part of the return data you see when running the command from the Master using `salt`), making it unnecessary to tail the minion log. More information on `salt-call` and how to use it can be found here.

#### Grains

Salt uses a system called Grains to build up static data about minions. This data includes information about the operating system that is running, CPU architecture and much more. The grains system is used throughout Salt to deliver platform data to many components and to users.

Grains can also be statically set, this makes it easy to assign values to minions for grouping and managing.

A common practice is to assign grains to minions to specify what the role or roles a minion might be. These static grains can be set in the minion configuration file or via the `grains.setval` function.

#### Targeting

Salt allows for minions to be targeted based on a wide range of criteria. The default targeting system uses globular expressions to match minions, hence if there are minions named `larry1`, `larry2`, `curly1`, and `curly2`, a glob of `larry*` will match `larry1` and `larry2`, and a glob of `*1` will match `larry1` and `curly1`.

Many other targeting systems can be used other than globs, these systems include:

Regular Expressions

  Target using PCRE-compliant regular expressions

Grains

  Target based on grains data: Targeting with Grains

Pillar

  Target based on pillar data: Targeting with Pillar

IP

  Target based on IP address/subnet/range

Compound

  Create logic to target based on multiple targets: Targeting with Compound

Nodegroup

  Target with nodegroups: Targeting with Nodegroup

The concepts of targets are used on the command line with Salt, but also function in many other areas as well, including the state system and the systems used for ACLs and user permissions.

#### Passing in Arguments

Many of the functions available accept arguments which can be passed in on the command line:

    salt '*' pkg.install vim

This example passes the argument `vim` to the pkg.install function. Since many functions can accept more complex input than just a string, the arguments are parsed through YAML, allowing for more complex data to be sent on the command line:

    salt '*' test.echo 'foo: bar'

In this case Salt translates the string 'foo: bar' into the dictionary "{'foo': 'bar'}"

Note

Any line that contains a newline will not be parsed by YAML.

## Salt States

Now that the basics are covered the time has come to evaluate `States`. Salt `States`, or the `State System` is the component of Salt made for configuration management.

The state system is already available with a basic Salt setup, no additional configuration is required. States can be set up immediately.

Note

Before diving into the state system, a brief overview of how states are constructed will make many of the concepts clearer. Salt states are based on data modeling and build on a low level data structure that is used to execute each state function. Then more logical layers are built on top of each other.

The high layers of the state system which this tutorial will cover consists of everything that needs to be known to use states, the two high layers covered here are the sls layer and the highest layer highstate.

Understanding the layers of data management in the State System will help with understanding states, but they never need to be used. Just as understanding how a compiler functions assists when learning a programming language, understanding what is going on under the hood of a configuration management system will also prove to be a valuable asset.

### The First SLS Formula

The state system is built on SLS (SaLt State) formulas. These formulas are built out in files on Salt's file server. To make a very basic SLS formula open up a file under /srv/salt named vim.sls. The following state ensures that vim is installed on a system to which that state has been applied.

`/srv/salt/vim.sls:`

    vim:
      pkg.installed

Now install vim on the minions by calling the SLS directly:

    salt '*' state.apply vim

This command will invoke the state system and run the `vim` SLS.

Now, to beef up the vim SLS formula, a `vimrc` can be added:

`/srv/salt/vim.sls:`

    vim:
      pkg.installed: []

    /etc/vimrc:
      file.managed:
        - source: salt://vimrc
        - mode: 644
        - user: root
        - group: root

Now the desired `vimrc` needs to be copied into the Salt file server to `/srv/salt/vimrc`. In Salt, everything is a file, so no path redirection needs to be accounted for. The `vimrc` file is placed right next to the `vim.sls` file. The same command as above can be executed to all the vim SLS formulas and now include managing the file.

Note

Salt does not need to be restarted/reloaded or have the master manipulated in any way when changing SLS formulas. They are instantly available.

### Adding Some Depth

Obviously maintaining SLS formulas right in a single directory at the root of the file server will not scale out to reasonably sized deployments. This is why more depth is required. Start by making an nginx formula a better way, make an nginx subdirectory and add an init.sls file:

`/srv/salt/nginx/init.sls:`

    nginx:
      pkg.installed: []
      service.running:
        - require:
          - pkg: nginx

A few concepts are introduced in this SLS formula.

First is the service statement which ensures that the `nginx` service is running.

Of course, the nginx service can't be started unless the package is installed -- hence the `require` statement which sets up a dependency between the two.

The `require` statement makes sure that the required component is executed before and that it results in success.

Note

The require option belongs to a family of options called requisites. Requisites are a powerful component of Salt States, for more information on how requisites work and what is available see: Requisites

Also evaluation ordering is available in Salt as well: Ordering States

This new sls formula has a special name -- `init.sls`. When an SLS formula is named `init.sls` it inherits the name of the directory path that contains it. This formula can be referenced via the following command:

    salt '*' state.apply nginx

Note

`state.apply` is just another remote execution function, just like `test.version` or `disk.usage`. It simply takes the name of an SLS file as an argument.

Now that subdirectories can be used, the `vim.sls` formula can be cleaned up. To make things more flexible, move the `vim.sls` and vimrc into a new subdirectory called `edit` and change the `vim.sls` file to reflect the change:

`/srv/salt/edit/vim.sls:`

    vim:
      pkg.installed

    /etc/vimrc:
      file.managed:
        - source: salt://edit/vimrc
        - mode: 644
        - user: root
        - group: root

Only the source path to the vimrc file has changed. Now the formula is referenced as `edit.vim` because it resides in the edit subdirectory. Now the edit subdirectory can contain formulas for emacs, nano, joe or any other editor that may need to be deployed.

### Next Reading

Two walk-throughs are specifically recommended at this point. First, a deeper run through States, followed by an explanation of Pillar.

1. Starting States

2. Pillar Walkthrough

An understanding of Pillar is extremely helpful in using States.

### Getting Deeper Into States

Two more in-depth States tutorials exist, which delve much more deeply into States functionality.

1. How Do I Use Salt States?, covers much more to get off the ground with States.

2. The States Tutorial also provides a fantastic introduction.

These tutorials include much more in-depth information including templating SLS formulas etc.

## So Much More!

This concludes the initial Salt walk-through, but there are many more things still to learn! These documents will cover important core aspects of Salt:

- Pillar

- Job Management

A few more tutorials are also available:

- Remote Execution Tutorial

- Standalone Minion

This still is only scratching the surface, many components such as the reactor and event systems, extending Salt, modular components and more are not covered here. For an overview of all Salt features and documentation, look at the Table of Contents.