Accessing saltstack minion programmatically

Question

I have been wrestling with this problem for the past week and I fear my solution is not conventional according to the SaltStack documentation. We have about 20 minions running on various servers throughout the country and need to be able to not only monitor them, but also issue commands and mysql queries from time to time. This is very easy to do from the CLI via something like:

salt '[minion name here]' cmd.run "tail -4 /usr/local/bin/file.txt"

That would effectively return the last four line in file.txt on the server running that minion. However, what we want to do next is have a script that periodically pulls this file down and caches it on salt master. Since SaltStack is written in python it was a no-brainer to use the same language for our daemons/cron jobs. However, the problem we are running into is that we would very much like a way of interfacing with SaltStack without having to resort to running a process from within our python script. Currently we have the following line of code that does almost the same thing:

subprocess.Popen(['salt', minion, 'cmd.run', '"tail -4 /usr/local/bin/file.txt"', '--out', 'json'], stdout=subprocess.PIPE)

After reading into the documentation it has become apparent that there is a way to do this provided by SaltStack. The issue we're having is that we cannot figure out the code that is needed to actually run such a command without using the subprocess module. Furthermore, we wish to also execute remote mysql queries on some of these minions, but we're so inexperienced (or so stupid) that we cannot decipher what the relevant code should be.

For the purpose of an example, we would like to list all databases located on one of our nodes. We found the following two articles that explain how to do this, but we are confused as to what actually must be executed to get our final result.

https://docs.saltstack.com/en/2015.8/ref/clients/index.html
https://docs.saltstack.com/en/latest/ref/modules/all/salt.modules.mysql.html

From the mysql salt modules we would expect to be able to use salt.modules.mysql.db_list , but according to the documentation that function does not accept any parameters. How would we specify which minion we want to run the query on? I thought there would be some way of instantiating a new instance of salt.modules.mysql that held a reference to the minion in question, but no such functionality seems to exist. Can anyone help us with this issue?

Answer 1

If you execute modules from cli and your minion ids start with something specific, like db-00 and db-01 , you would do something like that:

salt 'db*' mysql.db_list

There are other approaches than relying on the minion id. Read more about targeting minions for further information.

From within python you can do the same as described within your linked docs . A slightly adjusted example:

import salt.client

local = salt.client.LocalClient()
local.cmd('db-*', 'mysql.db_list')