Ssh – Rolling update with puppet, ansible or fabric

ansiblefabricpuppetssh

I have some jetty servers with a loadbalancer before them. Now I want to update my application without downtime. When one jetty is going down and no longer reachable the loadbalancer automatically removes it from the list, so this is not the issue.

The main problem is to avoid down time: so, I have to make sure only one jetty is restarting at a time – or make sure that at least N jettys are online!

At the moment I'm using a simple bash script where I need to wait manually for one jetty to came back online again before restarting the next jetty and so on.

Now bash is not very optimal for this kind of stuff and I hope there are tools better suited to make the whole task automated. E.g. I could use a simple ping URL http://jetty-number-n.com/ping which responds OK (200) if the n-th jetty is online.

How could I solve this task and with which tool?

Thanks to @ceejayoz I found rolling update for ansible. But it is still suboptimal as I would need to set a fixed timeout.

Best Answer

This is fairly easy with Ansible. Rough pseudo-ansible playbook:

---
  - hosts: your_server_group
    sudo: yes
    serial: 1
    tasks:
      - shell: reboot now
      - wait_for: port=22
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