SaltStack¶

Guideline on India FutureSystems¶

You DON’T install Salt on India. If you see the cursor like:

[albert@i136 ~]$

You should NOT install any program.

You have to log into your VM instance to install Puppet. i136 is a India login node which is like a gateway. You are supposed not to perform any tasks on India, especially if you require root privileges. Please create a VM instance on India OpenStack and SSH into your VM to run and install your software. You will have a full access of your virtual machine instance.

root Access¶

We will install Salt and other software using root account. Using root account means that you have a permission to use entire system resources without any restriction. Since this lesson includes a couple of examples using Salt, we recommend to use OpenStack VM instance on FutureSystems. DON’T try to install Puppet on your local machine or on the india.futuresystems.org host. Use a benefit of VM instance which you can easily delete and re-create a new one.

On a VM instance, simply run a switch user command:

ubuntu@salt:~$ sudo su -

If you see root label, you are in root account on your machine:

root@salt:~#

Update Hostname¶

If you see sudo: unable to resolve host, try to add hostname with the following command:

echo -e "\n127.0.1.1 $HOSTNAME" >> /etc/hosts

Ubuntu¶

First, add the salt repository.

sudo add-apt-repository ppa:saltstack/salt
sudo apt-get update

Core components will be installed with the following commands. If you run Salt in a local mode, install salt-minion only. The master, minion, or syndic will be installed.

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

A few more components are also installed with the following commands. The salt-cloud, salt-ssh, and salt-api will be installed.

sudo apt-get install salt-cloud
sudo apt-get install salt-ssh
sudo apt-get install salt-api

One-Line Installation Salt Minion¶

With a caution, one-line installation can be used to have a quick installation on various operating systems.

sudo sh ins://bootstrap.saltstack.com | sudo sh -s -- git develop

Or two lines will be used:

curl -L https://bootstrap.saltstack.com -o install_salt.sh
sudo sh install_salt.sh

SLS Files¶

SaLt State file (SLS) is instructions of tasks in which a system should be in, and what applications should be installed and configured. SLS data is written in a simple format, YAML file with a .sls file extension. This is often called configuration management. We will create a few files to try a simple example of starting a Apache web server so that you can understand basic flows in the use case.

Salt State Tree¶

Salt state tree is a collection of SLS files that live under the directory specified in file_roots. We use a default directory /srv/salt to store sls files.

sudo mkdir /srv/salt

Top File¶

The top file (top.sls) is to map what SLS modules get loaded onto what minions via the state system. For example apache sls module can be loaded to install and run on the target machine using top.sls file. The top file creates a few general abstractions. First, it maps what nodes should pull from which environments, next it defines which matches systems should draw from.

• Create top.sls file for webserver:

  nano /srv/salt/top.sls
  

The base environment will be loaded. type the following three lines in the top.sls file:

base:
  '*':
    - webserver

• Create webserver.sls file to install Apache:

  nano /srv/salt/webserver.sls
  

The webserver.sls content include apache2 package installation:

apache2:              # ID declaration
  pkg:                # state declaration
    - installed       # function declaration

Test¶

Check your Apache is running with nc command.

nc -v -z salt 80

You have running Apache if you see the message like so:

Connection to salt 80 port [tcp/http] succeeded!

How It Works¶

The instructions we made are executed in the following order:

• The Salt minion reads the top.sls file and determines that it is a part of the group matched by * glob.
• It reads the webserver SLS and applies.
• webserver.sls file will be loaded and finds the apache state, which installs the Apache package.
• The Salt minion now have Apache web server installed.

Installation¶

We already installed a Salt master and a minion in the earlier section, but here is a reminder of the installation.

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:saltstack/salt
sudo apt-get update
sudo apt-get install salt-master
sudo apt-get install salt-minion
service salt-master start
service salt-minion start

If you don’t have salt-key or salt-master command, you need to run these commands.

List of Registered Minions¶

The following command Lists all public keys registered on the master. Salt uses key-based authentication so the registered keys are important to communicate each other.

salt-key -L

Our test machine (hostname: salt) may generate outputs like so:

Accepted Keys:
Unaccepted Keys:
salt
Rejected Keys:

The Unaccepted Keys means that there is no registered keys for the hosts, in this example, the salt host is not registered. What we need to do is simply registering the host with the following command:

salt-key -a '$HOSTNAME'

Use a different hostname if you have other name.

Once you registered your host, list public keys again to confirm that it’s registered. The output looks like this:

root@salt:~# salt-key -L
Accepted Keys:
salt
Unaccepted Keys:
Rejected Keys:

Nginx Installation and Start¶

Before we install and start Nginx web server, we may need to stop an Apache web server first which uses HTTP (80) port.

service apache2 stop

The following commands install nginx web server and starts its service.

salt '*' pkg.install nginx

The output looks like so:

salt:
    ----------
    nginx:
         ----------
         new:
             1.4.6-1ubuntu3.2
         old:
             1

The following command starts a nginx web server.

salt '*' service.start nginx

The output looks like so:

salt:
    True

• ‘*’: all hosts The ‘*’ refers to all minions whose key is accepted. In this example, salt in only minion targeted to install nginx. The particular hostname can be speicified e.g. salt 'salt' ....
• pkg.install: Install a package, refresh=True option can be added to update the dpkg database.

Ping¶

To check remote machines are alive, we can use ping.

root@salt:~# salt '*' test.ping
salt:
    True

System Command¶

If you have a system command to execute remotely, you can use cmd.run sub-command. Our test result looks like so:

root@salt:~# salt '*' cmd.run 'ifconfig'
salt:

  eth0      Link encap:Ethernet  HWaddr fa:16:3e:6d:a1:40
            inet addr:10.23.0.1  Bcast:10.23.3.255  Mask:255.255.252.0
            inet6 addr: fe80::f816:3eff:fe6d:a140/64 Scope:Link
            UP BROADCAST RUNNING MULTICAST  MTU:1400  Metric:1
            RX packets:95868 errors:0 dropped:0 overruns:0 frame:0
            TX packets:64074 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:1000
            RX bytes:83533414 (83.5 MB)  TX bytes:7411580 (7.4 MB)

  lo        Link encap:Local Loopback
            inet addr:127.0.0.1  Mask:255.0.0.0
            inet6 addr: ::1/128 Scope:Host
            UP LOOPBACK RUNNING  MTU:65536  Metric:1
            RX packets:4798 errors:0 dropped:0 overruns:0 frame:0
            TX packets:4798 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:0
            RX bytes:1541859 (1.5 MB)  TX bytes:1541859 (1.5 MB)

sys.doc¶

It returns all possible sub commands.

::

salt ‘*’ sys.doc

Exercise I¶

SaltStack.1:

1. Turn on the type script by ``script salt_ex1_$USERNAME.txt` (Replace $USERNAME with your id)
2. Install Python virtualenv using salt.
3. Run virtualenv --version.
4. Type exit to save the script.
5. Submit salt_ex1_$USERNAME.txt file.