HowTo: Upgrade Salt-Minions and Don’t Lose Them

If you try to upgrade salt-minions from the salt-master, in most cases salt-master would probably lose access to the minions.

If the access is lost, you would have to log in to each host and restart the salt-minion service manually to make it communicate back with the salt-master.

This problem is caused by the salt-minion service that often doesn’t restart after update.

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In this article i’ll show how to safely update salt-minions from the salt-master without loosing communication.

Upgrade Salt-Master

First of all it is required to upgrade salt-master.

Upgrade order: According to documentation, the master should always be upgraded first, as the backward compatibility for minions running newer versions of salt than their masters is not guaranteed.

Upgrade salt-master on CentOS, RHEL, etc.:

$ sudo yum update salt-master

Upgrade salt-master on Debian, Ubuntu, Linux Mint, etc.:

$ sudo apt-get update  salt-master

To find out the current version of the salt-master, run:

$ salt-master --version

Upgrade Salt-Minion

For the moment there is no a normal way to upgrade salt-minions from the salt-master and not to lose communication between them.

But you can create a salt-state, that will send a special shell command to the salt-minion and execute it in the background.

This shell command will update and restart the salt-minion service using the locally executed salt-call.

After the salt-minion is restarted, communication with the salt-master would be successfully recovered.

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At the same time the below state beforehand checks if a new version of the salt-minion packaged is available to avoid useless restart of the salt-minion service.

Create the following state on the salt-master and apply it to the salt-minions to upgrade them safely:

Upgrade Salt-Minion:
  cmd.run:
    - name: |
        exec 0>&- # close stdin
        exec 1>&- # close stdout
        exec 2>&- # close stderr
        nohup /bin/sh -c 'salt-call --local pkg.install salt-minion && salt-call --local service.restart salt-minion' &
    - onlyif: "[[ $(salt-call --local pkg.upgrade_available salt-minion 2>&1) == *'True'* ]]" 

To find out the current version of your salt-minions from the salt-master, run:

$ sudo salt '*' test.version

5 Replies to “HowTo: Upgrade Salt-Minions and Don’t Lose Them”

  1. Спасибо, за статью. Помогло.

  2. Nice, thanks.

  3. Не работает, состояние применяется, но не обновляет

    [DEBUG   ] LazyLoaded highstate.output
    ukm5_1:
    ----------
              ID: update
        Function: cmd.run
            Name: exec 0>&- # close stdin
    exec 1>&- # close stdout                                                                                                                                                                      
    exec 2>&- # close stderr                                                                                                                                                                      
    nohup /bin/sh -c 'salt-call --local pkg.install salt-minion && salt-call --local service.restart salt-minion' &                                                                               
                                                                                                                                                                                                  
          Result: True
         Comment: onlyif condition is false
         Started: 15:35:19.891055
        Duration: 4239.552 ms
         Changes:   
    
    Summary for ukm5_1                                                                                                                                                                            
    ------------                                                                                                                                                                                  
    Succeeded: 1
    Failed:    0
    ------------
    Total states run:     1                                                                                                                                                                       
    Total run time:   4.240 s
    
  4. Достаточно просто
    “`
    Upgrade Salt-Minion:
    cmd.run:
    – name: |
    exec 0>&- # close stdin
    exec 1>&- # close stdout
    exec 2>&- # close stderr
    nohup /bin/sh -c ‘salt-call –local pkg.install salt-minion only_upgrade=True && salt-call –local service.restart salt-minion’ &
    “`

  5. Will the same works for windows as well?

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