Use Pssh To Restart A Service

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Hi all,

I need to restart a service on a few elasticsearch nodes. I’m trying to do it with pssh.

I’m getting this error when I try to do that:

pssh -h es_list “/bin/sudo -S /bin/systemctl restart elasticsearch”
[1] 17:01:50 [FAILURE] bluethundr@es2.example.com Exited with error code 1
[2] 17:01:51 [FAILURE] bluethundr@es3.example.com Exited with error code 1
[3] 17:01:51 [FAILURE] bluethundr@es1.example.com Exited with error code 1

I have to sudo up from my user account as root logins are disallowed.

However a simple ‘echo hello’ command that doesn’t require sudo works fine:

#pssh -h es_list “/bin/echo hello”
[1] 17:00:40 [SUCCESS] bluethundr@es1.example.com
[2] 17:00:41 [SUCCESS] bluethundr@es3.example.com
[3] 17:00:41 [SUCCESS] bluethundr@es2.example.com

What am I doing wrong?

Thanks, Tim

10 thoughts on - Use Pssh To Restart A Service

  • Have you tried running the command from a conventional login?

    sudo -S
    expects a password from stdin, where is that being supplied?

  • The default configuration prohibits use if input echo can’t be disabled. That means no “-S”.

    I modify that for users where necessary:

    /etc/sudoers.d/myuser:
    Defaults:myuser !requiretty, visiblepw

  • This is all the secure logs say about the SSH session:

    [root@logs:~] #tail -f /var/log/secure Oct 31 19:15:20 logs sshd[24407]: Accepted publickey for bluethundr from
    47.18.111.100 port 47469 ssh2: RSA
    ae:62:1f:de:54:89:af:2c:10:16:0e:fd:8d:7e:81:06
    Oct 31 19:15:21 logs sshd[24407]: pam_unix(sshd:session): session opened for user bluethundr by (uid=0)
    Oct 31 19:15:21 logs sshd[24410]: Received disconnect from 47.18.111.100:
    11: disconnected by user Oct 31 19:15:21 logs sshd[24407]: pam_unix(sshd:session): session closed for user bluethundr

    No change in the logs after making the suggested change to disable tty:

    [root@logs:~] #cat /etc/sudoers.d/bluethundr Defaults:myuser !requiretty, visiblepw

    Got the same exact message!

    Anything else I can try?

    Thanks

  • Can you try:
    ‘sh -c “/bin/sudo -S /bin/systemctl restart elasticsearch”‘

    Or perhaps without the single quotes, as well.

  • I think you need to double-check your sudoers file. Use the ‘-i’
    argument to pssh to get more information.

    # cat /etc/sudoers.d/gordon gordon ALL=(ALL) NOPASSWD: ALL

    $ pssh -h t -i sudo echo true
    [1] 16:02:12 [FAILURE] MYHOST Exited with error code 1
    Stderr: sudo: sorry, you must have a tty to run sudo

    # cat /etc/sudoers.d/gordon Defaults:gordon !requiretty, visiblepw gordon ALL=(ALL) NOPASSWD: ALL

    $ pssh -h t -i sudo echo true
    [1] 16:02:30 [SUCCESS] MYHOST
    true

  • Hey Gordon,

    Sorry, man my bad! Disabling the tty requirement for my sudo user does indeed work. I had a type-o in the sudoers file, and when I corrected it, my sudo command via pssh started working!

    #pssh -i -h es_list “/bin/sudo /bin/systemctl restart elasticsearch; sleep
    10”
    [1] 20:31:32 [SUCCESS] bluethundr@es3.jokefire.com Stderr: sudo: sorry, you must have a tty to run sudo
    [2] 20:31:32 [SUCCESS] bluethundr@es2.jokefire.com
    [3] 20:31:32 [SUCCESS] bluethundr@es1.jokefire.com

    I’m still getting the ‘sorry you must have a tty to run sudo’ message coming from one of the nodes. But the command succeeds so it’s no big deal!
    Odd tho that one node would be barking about that, considering my sudoers is distributed via puppet.

    Anyway, it’s all good as far as I’m concerned. At least this works! I’ll check that 3rd node and see if there’s any difference to the sudoers file I
    guess.

    Thanks for your help!
    Tim

  • This is why it is paramount to use visudo command as opposed editing the /etc/sudoers file directly! The visudo command will check the edited temporary sudoers file syntax before committing to /etc!

    ak.

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