Run a reactor or state on one minion in a glob of minions?

[Mike]

Lets say I want to run a reactor or a salt '*' command and target a bunch of minions, but I only want it to run on the first minion targeted (or some random minion in the target list).  How would I do that?

[Christopher Baklid]

If I understand you right, you just want to target a single random minion?

You could do that in a runner, essentially pull a list of minions and use random.choice() to select one to run a command on

When I've had some sleep I can write you a full example, otherwise this is a good place to start:

Configuring saltstack to use custom runners https://docs.saltstack.com/en/latest/ref/configuration/master.html#runner-dirs

Writing Runners https://docs.saltstack.com/en/latest/ref/runners/

Using the client API https://docs.saltstack.com/en/2015.8/ref/clients/index.html#localclient

[Christopher Baklid]

Here's what I had in mind:

A custom runner in the '/srv/salt/_runners/'

# /srv/salt/_runners/rnd.py
import salt.client
import salt.config
import salt.runner
from random import choice


def target():
 # load master config
 opts = salt.config.master_config('/etc/salt/master')


 # load runner client with master config
 runner = salt.runner.RunnerClient(opts)


 # run manage.up to fetch active minions
 list_of_minions = runner.cmd('manage.up', [])


 # let python randomly choose a minion
 random_target = choice(list_of_minions)


 # load the execution module client
 local = salt.client.LocalClient()


 # run execution module on randomly targeted minion
 return local.cmd(random_target, 'test.ping')

The reactor conf file

# /etc/salt/master.d/reactor.conf
reactor:
  - 'my/custom/event/':
    - /srv/reactor/random_target.sls

and lastly the reactor state

# /srv/reactor/random_target.sls
run_command_on_random_target:
  runner.rnd.target

I hope that's somewhat what you had in mind?

[Mike]

Yes, this looks great.  Thank you.