Masterless Salt

In this chapter, we've taken the time to set up Salt in a master-minion relationship. This will allow us to take advantage of all the power of Salt and scale to multiple minions easily later on. However, Salt is also designed so that a minion can run without a master.

We'll run through a few examples of how to run commands on a minion. This will also be useful even when we do have a master because if we're logged into a minion for some reason and want to run a command while we're there, we can do so using these same concepts.

To start, we'll leave our master running. The command used to run commands on the minion is salt-call, and it can take any of the same execution module functions that we used with the salt command, as follows:

# sudo salt-call test.ping
local:
    True

Note that it doesn't display our minion's ID because we're just running it locally:

# sudo salt-call test.fib 10
local:
    |_
      - 0
      - 1
      - 1
      - 2
      - 3
      - 5
      - 8
    - 5.00679016113e-06
# sudo salt-call sys.doc test.ping
local:
    ----------
    test.ping:

            Used to make sure the minion is up and responding. Not
            an ICMP ping.

            Returns ``True``.

            CLI Example:

                salt '*' test.ping

Now, let's stop our master and try again:

# sudo service salt-master stop
# sudo salt-call test.ping
Failed sign in

The example shown previously will take a fairly long time to terminate. Basically, salt-call is trying to establish a connection with the master just in case it needs to copy files from the master or other similar operations.

In order for salt-call to operate properly without a master, we need to tell it that there's no master. We do this with the --local flag, as follows:

# sudo salt-call --local test.ping
local:
    True

Success! You can now operate a Salt minion without a master!

# sudo service salt-master start