Pillar Walkthrough¶

Setting Up Pillar¶

The pillar is already running in Salt by default. To see the minion's pillar data:

salt '*' pillar.items

By default the contents of the master configuration file are loaded into pillar for all minions. This enables the master configuration file to be used for global configuration of minions.

Similar to the state tree, the pillar is comprised of sls files and has a top file. The default location for the pillar is in /srv/pillar.

To start setting up the pillar, the /srv/pillar directory needs to be present:

mkdir /srv/pillar

Now create a simple top file, following the same format as the top file used for states:

/srv/pillar/top.sls:

base:
  '*':
    - data

This top file associates the data.sls file to all minions. Now the /srv/pillar/data.sls file needs to be populated:

/srv/pillar/data.sls:

info: some data

To ensure that the minions have the new pillar data, issue a command to them asking that they fetch their pillars from the master:

salt '*' saltutil.refresh_pillar

Now that the minions have the new pillar, it can be retrieved:

salt '*' pillar.items

The key info should now appear in the returned pillar data.

users:
  thatch: 1000
  shouse: 1001
  utahdave: 1002
  redbeard: 1003

base:
  '*':
    - data
    - users

{% for user, uid in pillar.get('users', {}).items() %}
{{user}}:
  user.present:
    - uid: {{uid}}
{% endfor %}

Parameterizing States With Pillar¶

Pillar data can be accessed in state files to customise behavior for each minion. All pillar (and grain) data applicable to each minion is substituted into the state files through templating before being run. Typical uses include setting directories appropriate for the minion and skipping states that don't apply.

A simple example is to set up a mapping of package names in pillar for separate Linux distributions:

/srv/pillar/pkg/init.sls:

pkgs:
  {% if grains['os_family'] == 'RedHat' %}
  apache: httpd
  vim: vim-enhanced
  {% elif grains['os_family'] == 'Debian' %}
  apache: apache2
  vim: vim
  {% elif grains['os'] == 'Arch' %}
  apache: apache
  vim: vim
  {% endif %}

The new pkg sls needs to be added to the top file:

/srv/pillar/top.sls:

base:
  '*':
    - data
    - users
    - pkg

Now the minions will auto map values based on respective operating systems inside of the pillar, so sls files can be safely parameterized:

/srv/salt/apache/init.sls:

apache:
  pkg.installed:
    - name: {{ pillar['pkgs']['apache'] }}

Or, if no pillar is available a default can be set as well:

/srv/salt/apache/init.sls:

apache:
  pkg.installed:
    - name: {{ salt['pillar.get']('pkgs:apache', 'httpd') }}

In the above example, if the pillar value pillar['pkgs']['apache'] is not set in the minion's pillar, then the default of httpd will be used.

Pillar Makes Simple States Grow Easily¶

One of the design goals of pillar is to make simple sls formulas easily grow into more flexible formulas without refactoring or complicating the states.

A simple formula:

/srv/salt/edit/vim.sls:

vim:
  pkg.installed: []

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

Can be easily transformed into a powerful, parameterized formula:

/srv/salt/edit/vim.sls:

vim:
  pkg.installed:
    - name: {{ pillar['pkgs']['vim'] }}

/etc/vimrc:
  file.managed:
    - source: {{ pillar['vimrc'] }}
    - mode: 644
    - user: root
    - group: root
    - require:
      - pkg: vim

Where the vimrc source location can now be changed via pillar:

/srv/pillar/edit/vim.sls:

{% if grains['id'].startswith('dev') %}
vimrc: salt://edit/dev_vimrc
{% elif grains['id'].startswith('qa') %}
vimrc: salt://edit/qa_vimrc
{% else %}
vimrc: salt://edit/vimrc
{% endif %}

Ensuring that the right vimrc is sent out to the correct minions.

Setting Pillar Data on the Command Line¶

Pillar data can be set on the command line when running state.apply <salt.modules.state.apply_() like so:

salt '*' state.apply pillar='{"foo": "bar"}'
salt '*' state.apply my_sls_file pillar='{"hello": "world"}'

The example below will swap the value for vim with telnet in the previously specified list, notice the nested pillar dict:

salt '*' state.apply edit.vim pillar='{"pkgs": {"vim": "telnet"}}'

More On Pillar¶

Pillar data is generated on the Salt master and securely distributed to minions. Salt is not restricted to the pillar sls files when defining the pillar but can retrieve data from external sources. This can be useful when information about an infrastructure is stored in a separate location.

Reference information on pillar and the external pillar interface can be found in the Salt documentation:

Pillar

Minion Config in Pillar¶

Minion configuration options can be set on pillars. Any option that you want to modify, should be in the first level of the pillars, in the same way you set the options in the config file. For example, to configure the MySQL root password to be used by MySQL Salt execution module:

mysql.pass: hardtoguesspassword

This is very convenient when you need some dynamic configuration change that you want to be applied on the fly. For example, there is a chicken and the egg problem if you do this:

mysql-admin-passwd:
  mysql_user.present:
    - name: root
    - password: somepasswd

mydb:
  mysql_db.present

The second state will fail, because you changed the root password and the minion didn't notice it. Setting mysql.pass in the pillar, will help to sort out the issue. But always change the root admin password in the first place.

This is very helpful for any module that needs credentials to apply state changes: mysql, keystone, etc.