Commit c79ad59c authored by Daniel Dehennin's avatar Daniel Dehennin
Browse files

feat(config): generate the deployment configuration file

parent e3f57b41
# -*- coding: utf-8 -*-
# vim: ft=sls
{#- Get the `tplroot` from `tpldir` #}
{%- set tplroot = tpldir.split('/')[0] %}
{%- set sls_service_dead = tplroot ~ '.service.dead' %}
{%- from tplroot | path_join("map.jinja") import discourse with context %}
include:
- {{ sls_service_dead }}
discourse-config-clean-file-absent:
file.absent:
- name: {{ discourse.config }}
- require:
- sls: {{ sls_service_dead }}
# -*- coding: utf-8 -*-
# vim: ft=sls
{#- Get the `tplroot` from `tpldir` #}
{%- set tplroot = tpldir.split('/')[0] %}
{%- set sls_git_clone = tplroot ~ '.git.clone' %}
{%- from tplroot | path_join("map.jinja") import discourse with context %}
{%- from tplroot | path_join("libtofs.jinja") import files_switch with context %}
include:
- {{ sls_git_clone }}
{%- set config = discourse.directory | path_join('containers', 'app.yml') %}
discourse-config-file-file-managed:
file.managed:
- name: {{ config }}
- source: {{ files_switch(['app.yml.jinja'],
lookup='discourse-config-file-file-managed',
use_subpath=True
)
}}
- mode: 644
- user: root
- group: root
- makedirs: True
- template: jinja
- context:
discourse: {{ discourse | json }}
- require:
- sls: {{ sls_git_clone }}
## this is the all-in-one, standalone Discourse Docker container template
##
## After making changes to this file, you MUST rebuild
## /var/discourse/launcher rebuild app
##
## BE *VERY* CAREFUL WHEN EDITING!
## YAML FILES ARE SUPER SUPER SENSITIVE TO MISTAKES IN WHITESPACE OR ALIGNMENT!
## visit http://www.yamllint.com/ to validate this file as needed
templates:
- "templates/postgres.template.yml"
- "templates/redis.template.yml"
- "templates/web.template.yml"
- "templates/web.ratelimited.template.yml"
## Uncomment these two lines if you wish to add Lets Encrypt (https)
{%- if discourse | traverse('letsencrypt:enabled', False) | to_bool %}
- "templates/web.ssl.template.yml"
- "templates/web.letsencrypt.ssl.template.yml"
{%- endif %}
## which TCP/IP ports should this container expose?
## If you want Discourse to share a port with another webserver like Apache or nginx,
## see https://meta.discourse.org/t/17247 for details
expose:
- "80:80" # http
{%- if discourse | traverse('letsencrypt:enabled', False) | to_bool %}
- "443:443" # https
{%- endif %}
params:
db_default_text_search_config: "pg_catalog.english"
## Set db_shared_buffers to a max of 25% of the total memory.
## will be set automatically by bootstrap based on detected RAM, or you can override
db_shared_buffers: "2048MB"
## can improve sorting performance, but adds memory usage per-connection
#db_work_mem: "40MB"
## Which Git revision should this container use? (default: tests-passed)
#version: tests-passed
env:
LANG: en_US.UTF-8
# DISCOURSE_DEFAULT_LOCALE: en
## How many concurrent web requests are supported? Depends on memory and CPU cores.
## will be set automatically by bootstrap based on detected CPUs, or you can override
UNICORN_WORKERS: 8
## TODO: The domain name this Discourse instance will respond to
## Required. Discourse will not work with a bare IP number.
DISCOURSE_HOSTNAME: {{ discourse.hostname }}
## Uncomment if you want the container to be started with the same
## hostname (-h option) as specified above (default "$hostname-$config")
#DOCKER_USE_HOSTNAME: true
## TODO: List of comma delimited emails that will be made admin and developer
## on initial signup example 'user1@example.com,user2@example.com'
DISCOURSE_DEVELOPER_EMAILS: {{ discourse.developer_emails }}
## TODO: The SMTP mail server used to validate new accounts and send notifications
# SMTP ADDRESS, username, and password are required
# WARNING the char '#' in SMTP password can cause problems!
DISCOURSE_SMTP_ADDRESS: {{ discourse | traverse('smtp:address') }}
DISCOURSE_SMTP_PORT: {{ discourse | traverse('smtp:port') }}
DISCOURSE_SMTP_USER_NAME: {{ discourse | traverse('smtp:user_name') }}
DISCOURSE_SMTP_PASSWORD: {{ discourse | traverse('smtp:password') }}
DISCOURSE_SMTP_ENABLE_START_TLS: {{ discourse | traverse('smtp:start_tls') | lower }} # (optional, default true)
## If you added the Lets Encrypt template, uncomment below to get a free SSL certificate
{%- if discourse | traverse('letsencrypt:enabled', False) | to_bool %}
LETSENCRYPT_ACCOUNT_EMAIL: {{ discourse | traverse('letsencrypt:account_email') }}
{%- endif %}
## The http or https CDN address for this Discourse instance (configured to pull)
## see https://meta.discourse.org/t/14857 for details
#DISCOURSE_CDN_URL: https://discourse-cdn.example.com
## The Docker container is stateless; all data is stored in /shared
volumes:
- volume:
host: {{ discourse.directory | path_join('shared', 'standalone') }}
guest: /shared
- volume:
host: {{ discourse.directory | path_join('shared', 'standalone', 'log', 'var-log') }}
guest: /var/log
## Plugins go here
## see https://meta.discourse.org/t/19157 for details
hooks:
after_code:
- exec:
cd: $home/plugins
cmd:
- git clone https://github.com/discourse/docker_manager.git
## Any custom commands to run after building
run:
- exec: echo "Beginning of custom commands"
## If you want to set the 'From' email address for your first registration, uncomment and change:
## After getting the first signup email, re-comment the line. It only needs to run once.
#- exec: rails r "SiteSetting.notification_email='info@unconfigured.discourse.org'"
- exec: echo "End of custom commands"
# -*- coding: utf-8 -*-
# vim: ft=sls
include:
- .file
{%- macro files_switch(source_files,
lookup=None,
default_files_switch=['id', 'os_family'],
indent_width=6,
use_subpath=False) %}
{#-
Returns a valid value for the "source" parameter of a "file.managed"
state function. This makes easier the usage of the Template Override and
Files Switch (TOFS) pattern.
Params:
* source_files: ordered list of files to look for
* lookup: key under '<tplroot>:tofs:source_files' to prepend to the
list of source files
* default_files_switch: if there's no config (e.g. pillar)
'<tplroot>:tofs:files_switch' this is the ordered list of grains to
use as selector switch of the directories under
"<path_prefix>/files"
* indent_width: indentation of the result value to conform to YAML
* use_subpath: defaults to `False` but if set, lookup the source file
recursively from the current state directory up to `tplroot`
Example (based on a `tplroot` of `xxx`):
If we have a state:
Deploy configuration:
file.managed:
- name: /etc/yyy/zzz.conf
- source: {{ files_switch(['/etc/yyy/zzz.conf', '/etc/yyy/zzz.conf.jinja'],
lookup='Deploy configuration'
) }}
- template: jinja
In a minion with id=theminion and os_family=RedHat, it's going to be
rendered as:
Deploy configuration:
file.managed:
- name: /etc/yyy/zzz.conf
- source:
- salt://xxx/files/theminion/etc/yyy/zzz.conf
- salt://xxx/files/theminion/etc/yyy/zzz.conf.jinja
- salt://xxx/files/RedHat/etc/yyy/zzz.conf
- salt://xxx/files/RedHat/etc/yyy/zzz.conf.jinja
- salt://xxx/files/default/etc/yyy/zzz.conf
- salt://xxx/files/default/etc/yyy/zzz.conf.jinja
- template: jinja
#}
{#- Get the `tplroot` from `tpldir` #}
{%- set tplroot = tpldir.split('/')[0] %}
{%- set path_prefix = salt['config.get'](tplroot ~ ':tofs:path_prefix', tplroot) %}
{%- set files_dir = salt['config.get'](tplroot ~ ':tofs:dirs:files', 'files') %}
{%- set files_switch_list = salt['config.get'](
tplroot ~ ':tofs:files_switch',
default_files_switch
) %}
{#- Lookup source_files (v2), files (v1), or fallback to an empty list #}
{%- set src_files = salt['config.get'](
tplroot ~ ':tofs:source_files:' ~ lookup,
salt['config.get'](tplroot ~ ':tofs:files:' ~ lookup, [])
) %}
{#- Append the default source_files #}
{%- set src_files = src_files + source_files %}
{#- Only add to [''] when supporting older TOFS implementations #}
{%- set path_prefix_exts = [''] %}
{%- if use_subpath and tplroot != tpldir %}
{#- Walk directory tree to find {{ files_dir }} #}
{%- set subpath_parts = tpldir.lstrip(tplroot).lstrip('/').split('/') %}
{%- for path in subpath_parts %}
{%- set subpath = subpath_parts[0:loop.index] | join('/') %}
{%- do path_prefix_exts.append('/' ~ subpath) %}
{%- endfor %}
{%- endif %}
{%- for path_prefix_ext in path_prefix_exts|reverse %}
{%- set path_prefix_inc_ext = path_prefix ~ path_prefix_ext %}
{#- For older TOFS implementation, use `files_switch` from the config #}
{#- Use the default, new method otherwise #}
{%- set fsl = salt['config.get'](
tplroot ~ path_prefix_ext|replace('/', ':') ~ ':files_switch',
files_switch_list
) %}
{#- Append an empty value to evaluate as `default` in the loop below #}
{%- if '' not in fsl %}
{%- set fsl = fsl + [''] %}
{%- endif %}
{%- for fs in fsl %}
{%- for src_file in src_files %}
{%- if fs %}
{%- set fs_dirs = salt['config.get'](fs, fs) %}
{%- else %}
{%- set fs_dirs = salt['config.get'](tplroot ~ ':tofs:dirs:default', 'default') %}
{%- endif %}
{#- Force the `config.get` lookup result as a list where necessary #}
{#- since we need to also handle grains that are lists #}
{%- if fs_dirs is string %}
{%- set fs_dirs = [fs_dirs] %}
{%- endif %}
{%- for fs_dir in fs_dirs %}
{%- set url = [
'- salt:/',
path_prefix_inc_ext.strip('/'),
files_dir.strip('/'),
fs_dir.strip('/'),
src_file.strip('/'),
] | select | join('/') %}
{{ url | indent(indent_width, true) }}
{%- endfor %}
{%- endfor %}
{%- endfor %}
{%- endfor %}
{%- endmacro %}
.. _tofs_pattern:
TOFS: A pattern for using SaltStack
===================================
.. list-table::
:name: tofs-authors
:header-rows: 1
:stub-columns: 1
:widths: 2,2,3,2
* -
- Person
- Contact
- Date
* - Authored by
- Roberto Moreda
- moreda@allenta.com
- 29/12/2014
* - Modified by
- Daniel Dehennin
- daniel.dehennin@baby-gnu.org
- 07/02/2019
* - Modified by
- Imran Iqbal
- https://github.com/myii
- 23/02/2019
All that follows is a proposal based on my experience with `SaltStack <http://www.saltstack.com/>`_. The good thing of a piece of software like this is that you can "bend it" to suit your needs in many possible ways, and this is one of them. All the recommendations and thoughts are given "as it is" with no warranty of any type.
.. contents:: **Table of Contents**
Usage of values in pillar vs templates in ``file_roots``
--------------------------------------------------------
Among other functions, the *master* (or *salt-master*) serves files to the *minions* (or *salt-minions*). The `file_roots <http://docs.saltstack.com/en/latest/ref/file_server/file_roots.html>`_ is the list of directories used in sequence to find a file when a minion requires it: the first match is served to the minion. Those files could be `state files <http://docs.saltstack.com/en/latest/topics/tutorials/starting_states.html>`_ or configuration templates, among others.
Using SaltStack is a simple and effective way to implement configuration management, but even in a `non-multitenant <http://en.wikipedia.org/wiki/Multitenancy>`_ scenario, it is not a good idea to generally access some data (e.g. the database password in our `Zabbix <http://www.zabbix.com/>`_ server configuration file or the private key of our `Nginx <http://nginx.org/en/>`_ TLS certificate).
To avoid this situation we can use the `pillar mechanism <http://docs.saltstack.com/en/latest/topics/pillar/>`_, which is designed to provide controlled access to data from the minions based on some selection rules. As pillar data could be easily integrated in the `Jinja <http://docs.saltstack.com/en/latest/topics/tutorials/pillar.html>`_ templates, it is a good mechanism to store values to be used in the final rendering of state files and templates.
There are a variety of approaches on the usage of pillar and templates as seen in the `saltstack-formulas <https://github.com/saltstack-formulas>`_' repositories. `Some <https://github.com/saltstack-formulas/nginx-formula/pull/18>`_ `developments <https://github.com/saltstack-formulas/php-formula/pull/14>`_ stress the initial purpose of pillar data into a storage for most of the possible variables for a determined system configuration. This, in my opinion, is shifting too much load from the original template files approach. Adding up some `non-trivial Jinja <https://github.com/saltstack-formulas/nginx-formula/blob/f74254c07e188bd448eaf1c5f9c802d78c4c005e/nginx/files/default/nginx.conf>`_ code as essential part of composing the state file definitely makes SaltStack state files (hence formulas) more difficult to read. The extreme of this approach is that we could end up with a new render mechanism, implemented in Jinja, storing everything needed in pillar data to compose configurations. Additionally, we are establishing a strong dependency with the Jinja renderer.
In opposition to the *put the code in file_roots and the data in pillars* approach, there is the *pillar as a store for a set of key-values* approach. A full-blown configuration file abstracted in pillar and jinja is complicated to develop, understand and maintain. I think a better and simpler approach is to keep a configuration file templated using just a basic (non-extensive but extensible) set of pillar values.
On the reusability of SaltStack state files
-------------------------------------------
There is a brilliant initiative of the SaltStack community called `salt-formulas <https://github.com/saltstack-formulas>`_. Their goal is to provide state files, pillar examples and configuration templates ready to be used for provisioning. I am a contributor for two small ones: `zabbix-formula <https://github.com/saltstack-formulas/zabbix-formula>`_ and `varnish-formula <https://github.com/saltstack-formulas/varnish-formula>`_.
The `design guidelines <http://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html>`_ for formulas are clear in many aspects and it is a recommended reading for anyone willing to write state files, even non-formulaic ones.
In the next section, I am going to describe my proposal to extend further the reusability of formulas, suggesting some patterns of usage.
The Template Override and Files Switch (TOFS) pattern
-----------------------------------------------------
I understand a formula as a **complete, independent set of SaltStack state and configuration template files sufficient to configure a system**. A system could be something as simple as an NTP server or some other much more complex service that requires many state and configuration template files.
The customization of a formula should be done mainly by providing pillar data used later to render either the state or the configuration template files.
Example: NTP before applying TOFS
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Let's work with the NTP example. A basic formula that follows the `design guidelines <http://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html>`_ has the following files and directories tree:
.. code-block::
/srv/saltstack/salt-formulas/ntp-saltstack-formula/
ntp/
map.jinja
init.sls
conf.sls
files/
default/
etc/
ntp.conf.jinja
In order to use it, let's assume a `masterless configuration <http://docs.saltstack.com/en/latest/topics/tutorials/quickstart.html>`_ and this relevant section of ``/etc/salt/minion``:
.. code-block:: yaml
pillar_roots:
base:
- /srv/saltstack/pillar
file_client: local
file_roots:
base:
- /srv/saltstack/salt
- /srv/saltstack/salt-formulas/ntp-saltstack-formula
.. code-block:: jinja
{#- /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/map.jinja #}
{%- set ntp = salt['grains.filter_by']({
'default': {
'pkg': 'ntp',
'service': 'ntp',
'config': '/etc/ntp.conf',
},
}, merge=salt['pillar.get']('ntp:lookup')) %}
In ``init.sls`` we have the minimal states required to have NTP configured. In many cases ``init.sls`` is almost equivalent to an ``apt-get install`` or a ``yum install`` of the package.
.. code-block:: sls
## /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/init.sls
{%- from 'ntp/map.jinja' import ntp with context %}
Install NTP:
pkg.installed:
- name: {{ ntp.pkg }}
Enable and start NTP:
service.running:
- name: {{ ntp.service }}
- enabled: True
- require:
- pkg: Install NTP package
In ``conf.sls`` we have the configuration states. In most cases, that is just managing configuration file templates and making them to be watched by the service.
.. code-block:: sls
## /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/conf.sls
include:
- ntp
{%- from 'ntp/map.jinja' import ntp with context %}
Configure NTP:
file.managed:
- name: {{ ntp.config }}
- template: jinja
- source: salt://ntp/files/default/etc/ntp.conf.jinja
- watch_in:
- service: Enable and start NTP service
- require:
- pkg: Install NTP package
Under ``files/default``, there is a structure that mimics the one in the minion in order to avoid clashes and confusion on where to put the needed templates. There you can find a mostly standard template for the configuration file.
.. code-block:: jinja
{#- /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/files/default/etc/ntp.conf.jinja #}
{#- Managed by saltstack #}
{#- Edit pillars or override this template in saltstack if you need customization #}
{%- set settings = salt['pillar.get']('ntp', {}) %}
{%- set default_servers = ['0.ubuntu.pool.ntp.org',
'1.ubuntu.pool.ntp.org',
'2.ubuntu.pool.ntp.org',
'3.ubuntu.pool.ntp.org'] %}
driftfile /var/lib/ntp/ntp.drift
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
{%- for server in settings.get('servers', default_servers) %}
server {{ server }}
{%- endfor %}
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery
restrict 127.0.0.1
restrict ::1
With all this, it is easy to install and configure a simple NTP server by just running ``salt-call state.sls ntp.conf``: the package will be installed, the service will be running and the configuration should be correct for most of cases, even without pillar data.
Alternatively, you can define a highstate in ``/srv/saltstack/salt/top.sls`` and run ``salt-call state.highstate``.
.. code-block:: sls
## /srv/saltstack/salt/top.sls
base:
'*':
- ntp.conf
**Customizing the formula just with pillar data**, we have the option to define the NTP servers.
.. code-block:: sls
## /srv/saltstack/pillar/top.sls
base:
'*':
- ntp
.. code-block:: sls
## /srv/saltstack/pillar/ntp.sls
ntp:
servers:
- 0.ch.pool.ntp.org
- 1.ch.pool.ntp.org
- 2.ch.pool.ntp.org
- 3.ch.pool.ntp.org
Template Override
^^^^^^^^^^^^^^^^^
If the customization based on pillar data is not enough, we can override the template by creating a new one in ``/srv/saltstack/salt/ntp/files/default/etc/ntp.conf.jinja``
.. code-block:: jinja
{#- /srv/saltstack/salt/ntp/files/default/etc/ntp.conf.jinja #}
{#- Managed by saltstack #}
{#- Edit pillars or override this template in saltstack if you need customization #}
{#- Some bizarre configurations here #}
{#- ... #}
{%- for server in settings.get('servers', default_servers) %}
server {{ server }}
{%- endfor %}
This way we are locally **overriding the template files** offered by the formula in order to make a more complex adaptation. Of course, this could be applied as well to any of the files, including the state files.
Files Switch
^^^^^^^^^^^^
To bring some order into the set of template files included in a formula, as we commented, we suggest having a similar structure to a normal final file system under ``files/default``.
We can make different templates coexist for different minions, classified by any `grain <http://docs.saltstack.com/en/latest/topics/targeting/grains.html>`_ value, by simply creating new directories under ``files``. This mechanism is based on **using values of some grains as a switch for the directories under** ``files/``.
If we decide that we want ``os_family`` as switch, then we could provide the formula template variants for both the ``RedHat`` and ``Debian`` families.
.. code-block::
/srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/files/
default/
etc/
ntp.conf.jinja
RedHat/
etc/
ntp.conf.jinja
Debian/
etc/
ntp.conf.jinja
To make this work we need a ``conf.sls`` state file that takes a list of possible files as the configuration template.
.. code-block:: sls
## /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/conf.sls
include:
- ntp
{%- from 'ntp/map.jinja' import ntp with context %}
Configure NTP:
file.managed:
- name: {{ ntp.config }}
- template: jinja
- source:
- salt://ntp/files/{{ grains.get('os_family', 'default') }}/etc/ntp.conf.jinja
- salt://ntp/files/default/etc/ntp.conf.jinja
- watch_in:
- service: Enable and start NTP service
- require:
- pkg: Install NTP package
If we want to cover the possibility of a special template for a minion identified by ``node01`` then we could have a specific template in ``/srv/saltstack/salt/ntp/files/node01/etc/ntp.conf.jinja``.
.. code-block:: jinja
{#- /srv/saltstack/salt/ntp/files/node01/etc/ntp.conf.jinja #}
{#- Managed by saltstack #}
{#- Edit pillars or override this template in saltstack if you need customization #}
{#- Some crazy configurations here for node01 #}
{#- ... #}
To make this work we could write a specially crafted ``conf.sls``.
.. code-block:: sls
## /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/conf.sls
include:
- ntp
{%- from 'ntp/map.jinja' import ntp with context %}
Configure NTP:
file.managed:
- name: {{ ntp.config }}
- template: jinja
- source:
- salt://ntp/files/{{ grains.get('id') }}/etc/ntp.conf.jinja
- salt://ntp/files/{{ grains.get('os_family') }}/etc/ntp.conf.jinja
- salt://ntp/files/default/etc/ntp.conf.jinja
- watch_in:
- service: Enable and start NTP service
- require:
- pkg: Install NTP package
Using the ``files_switch`` macro
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
We can simplify the ``conf.sls`` with the new ``files_switch`` macro to use in the ``source`` parameter for the ``file.managed`` state.
.. code-block:: sls
## /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/conf.sls
include:
- ntp
{%- set tplroot = tpldir.split('/')[0] %}
{%- from 'ntp/map.jinja' import ntp with context %}
{%- from 'ntp/libtofs.jinja' import files_switch %}
Configure NTP:
file.managed:
- name: {{ ntp.config }}
- template: jinja
- source: {{ files_switch(['/etc/ntp.conf.jinja'],
lookup='Configure NTP'
)
}}
- watch_in:
- service: Enable and start NTP service
- require:
- pkg: Install NTP package
* This uses ``config.get``, searching for ``ntp:tofs:source_files:Configure NTP`` to determine the list of template files to use.
* If this returns a result, the default of ``['/etc/ntp.conf.jinja']`` will be appended to it.
* If this does not yield any results, the default of ``['/etc/ntp.conf.jinja']`` will be used.
In ``libtofs.jinja``, we define this new macro ``files_switch``.
.. literalinclude:: ../template/libtofs.jinja
:caption: /srv/saltstack/salt-formulas/ntp-saltstack-formula/ntp/libtofs.jinja
:language: jinja
How to customise the ``source`` further
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The examples below are based on an ``Ubuntu`` minion called ``theminion`` being configured via. pillar.
Using the default settings of the ``files_switch`` macro above,
the ``source`` will be:
.. code-block:: sls
- source:
- salt://ntp/files/theminion/etc/ntp.conf.jinja
- salt://ntp/files/Debian/etc/ntp.conf.jinja
- salt://ntp/files/default/etc/ntp.conf.jinja
Customise ``files``
~~~~~~~~~~~~~~~~~~~
The ``files`` portion can be customised:
.. code-block:: sls
ntp:
tofs:
dirs:
files: files_alt
Resulting in:
.. code-block:: sls
- source:
- salt://ntp/files_alt/theminion/etc/ntp.conf.jinja
- salt://ntp/files_alt/Debian/etc/ntp.conf.jinja
- salt://ntp/files_alt/default/etc/ntp.conf.jinja
Customise the use of grains