Fedora & CentOS / Enterprise Linux

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# Fedora & CentOS / Enterprise Linux

Beginning with version 0.9.4, Salt has been available in the primary Fedora repositories and EPEL. It is installable using yum. Fedora will have more up to date versions of Salt than other members of the Red Hat family, which makes it a great place to help improve Salt!

CentOS / RHEL 5

Salt and all dependencies have been finally accepted into the yum reposities for EPEL5 and EPEL6. Currently, the latest is in epel-testing while awaiting promotion to epel proper. You can install it via:

    yum --enablerepo=epel-testing install salt

On RHEL6, the proper jinja packages were moved from EPEL to the "RHEL Server Optional Channel". Verify this repository is enabled before installing salt on RHEL6.

## Installation

Salt can be installed using `yum` and is available in the standard Fedora repositories.

### Stable Release

Salt is packaged separately for the minion and the master. You'll only need to install the appropriate package for the role you need the machine to play. This means you're going to want one master and a whole bunch of minions!

    yum install salt-master
    yum install salt-minion

## Configuration

Below, we'll cover Salt Master and Minion configuration options.

## Master Configuration

This section outlines configuration of a Salt Master, which is used to control other machines known as "minions" (see "Minion Configuration" for instructions on configuring a minion). This will outline IP configuration, and a few key configuration paths.

Interface

By default the Salt master listens on TCP ports `4505` and `4506` on all interfaces (0.0.0.0). If you have a need to bind Salt to a specific IP, redefine the "interface" directive as seen here:

    - #interface: 0.0.0.0
    + interface: 10.0.0.1

Enable the Master

You'll also likely want to activate the Salt Master in systemd, configuring the Salt Master to start automatically at boot.

    systemctl enable salt-master.service

Start the Master

Once you've completed all of these steps you're ready to start your Salt Master. You should be able to start your Salt Master now using the command seen here:

    systemctl start salt-master.service

If your Salt Master doesn't start successfully, go back through each step and see if anything was missed. Salt doesn't take much configuration (part of its beauty!), and errors are usually simple mistakes.

## Minion Configuration

Configuring a Salt Minion is surprisingly simple. Unless you have a real need for customizing your minion configuration (which there are plenty of options if you are so inclined!), there is one simple directive that needs to be updated. That option is the location of the master.

By default a Salt Minion will try to connect to the dns name "salt". If you have the ability to update DNS records for your domain you might create an A or CNAME record for "salt" that points to your Salt Master. If you are able to do this you likely can do without any minion configuration at all.

If you are not able to update DNS, you'll simply need to update one entry in the configuration file. Using your favorite editor, open the minion configuration file and update the "master" entry as seen here:

    - #master: salt
    + master: 10.0.0.1

Simply update the master directive to the IP or hostname of your Salt Master. Save your changes and you're ready to start your Salt Minion. Advanced configuration options are covered in another chapter.

Enable the Minion

You'll need to configure the minion to auto-start at boot. You can toggle that option through systemd.

    systemctl enable salt-minion.service

Start the Minion

Once you've completed all of these steps, start the Minion. This command should do the trick:

    systemctl start salt-minion.service

If your Salt Minion doesn't start successfully, go back through each step and see if anything was missed. Salt doesn't take much configuration (part of its beauty!), and errors are usually simple mistakes.

## Tying It All Together

If you've successfully completed each of the steps above you should have a running Salt Master and a running Salt Minion. The Minion should be configured to point to the Master. To verify that there is communication flowing between the Minion and Master we'll run a few initial `salt` commands. These commands will validate the Minions RSA encryption key, and then send a test command to the Minion to ensure that commands and responses are flowing as expected.

Key Management

Salt uses AES encryption for all communication between the Master and the Minion. This ensures that the commands you send to your Minions (your cloud) can not be tampered with, and that communication between Master and Minion is only done through trusted, accepted keys.

Before you'll be able to do any remote execution or configuration management you'll need to accept any pending keys on the Master. Run the `salt-key` command to list the keys known to the Salt Master:

    [root@master ~]# salt-key -L
    Unaccepted Keys:
    alpha
    bravo
    charlie
    delta
    Accepted Keys:

This example shows that the Salt Master is aware of four Minions, but none of the keys have been accepted. To accept the keys and allow the Minions to be controlled by the Master, again use the `salt-key` command:

    [root@master ~]# salt-key -A
    [root@master ~]# salt-key -L
    Unaccepted Keys:
    Accepted Keys:
    alpha
    bravo
    charlie
    delta

The `salt-key` command allows for signing keys individually or in bulk. The example above, using `-A` bulk-accepts all pending keys. To accept keys individually use the lowercase of the same option, `-a keyname`.

## Sending Commands

Everything should be set for you to begin remote management of your Minions. Whether you have a few or a few-dozen, Salt can help you manage them easily!

For final verification, send a test function from your Salt Master to your minions. If all of your minions are properly communicating with your Master, you should "True" responses from each of them. See the example below to send the `test.ping` remote command:

    [root@master ~]# salt '*' test.ping
    {'alpha': True}

## Where Do I Go From Here

Congratulations! You've successfully configured your first Salt Minions and are able to send remote commands. I'm sure you're eager to learn more about what Salt can do. Depending on the primary way you want to manage your machines you may either want to visit the section regarding Salt States, or the section on Modules.

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