SaltStack: Execute custom execution module on Master using runner

2020-03-16T08:37:22Z

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Contents

• Introduction:
• Pre-Requisites
• Preparation
• Execution

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Introduction:

Execution modules are meant to executed on minions(clients). Therefore only a handful of execution/state modules are visible to salt-master. But sometimes we may need to execute our custom execution module on Master itself (most likely via runner). In order to do this salt-minion must be installed on Salt-Master box. And configure it to accept the commands from salt-master. This will be configured as a normal salt-minion. Nothing special needs to be done. We will create

• A custom execution module that accepts two arguments
• A custom runner module that accepts two arguments

Pre-Requisites

• salt-master installed and configured on a machine. I used fedora-24 VM.
• salt-minion installed and configured to accept command from salt-master.

Preparation

/etc/salt/master file used:

log_level: debug

fileserver_backend:
  - roots

file_roots:
  base:
    - /srv/salt

runner_dirs:
  - /srv/salt/_runners

/etc/salt/minion file used:

master: salt

Note: In /etc/salt/master file, log_level is set to debug. Normally this will be info.

my_module.py will be our execution module

mkdir /srv/salt/_modules
touch /srv/salt/_modules/my_module.py
mkdir /srv/salt/_runners
touch /srv/salt/_runners/my_runner.py

Contents of /srv/salt/_modules/my_module.py are as follows:

#! /usr/bin/env python

# Below virtual name can be any string.
__virtualname__ = 'my_module'

def __virtual__():
    return __virtualname__

def my_module_function(arg1, arg2):
    modified_arg1 = '%s_%s' % (arg1, 'modified')
    modified_arg2 = '%s_%s' % (arg2, 'modified')
    return modified_arg1, modified_arg2

Contents of /srv/salt/_runners/my_runner.py are as follows:

#! /usr/bin/env python
import salt.client
import salt.loader
import salt.config


def my_runner_function(arg1, arg2):
    __opts__ = salt.config.minion_config('/etc/salt/master')
    mods = salt.loader.minion_mods(__opts__)
    ret1, ret2 = mods['my_module.my_module_function'](arg1, arg2)
    return ret1, ret2

Execution

Run following command to sync all modules with all minions:

root@salt-master# salt '*' saltutil.sync_all
fedora2.vagrant.box:
    ----------
    beacons:
    engines:
    grains:
    log_handlers:
    modules:
        - modules.custom_module
        - modules.my_module
    output:
    proxymodules:
    renderers:
    returners:
    sdb:
    states:
    utils:
fedora.vagrant.box:
    ----------
    beacons:
    engines:
    grains:
    log_handlers:
    modules:
        - modules.custom_module
        - modules.my_module
    output:
    proxymodules:
    renderers:
    returners:
    sdb:
    states:
    utils:

Above runner can be called from command line as follows:

root@salt-master# salt-run my_runner.my_runner_function 'a_string' 'b_string'
- a_string_modified
- b_string_modified
[INFO    ] Runner completed: 20170109185717568738