Ansible delegation

By: జగదేశ్ on 4:35 PM

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Ansible by default run the task all at once on the remote configure machine. What If a task is based on status of a certain command on another machine?. Say if you are patching a package on a machine and you need to continue until a certain file is available on another machine. This is done in Ansible using the delegation option.

By using the Ansible delegate option we can configure to run a task on a different host than the one that is being configured using the delegate_to key. The module will still run once for every machine, but instead of running on the target machine, it will run on the delegated host. The facts available will be the ones applicable to the current host. Lets write a basic playbook using Ansible delegate

[root@vx111a delegate]# cat sample-playbook.yml

---

- hosts: cent

 

  tasks:

    - name: Install zenity

      action: yum name=zenity state=installed

    - name: configure zenity

      action: template src=hosts dest=/tmp/zenity.conf

    - name: Tell Master

      action: shell echo "{{ansible_fqdn}} done" >> /tmp/list

      delegate_to: 172.16.202.97

We have defined multiple tasks to install zenity, configure zenity and the last task is to echo command on the delegate machineof different IP address.  Ansible-playbook will delegate the last task to the IP address 172.16.202.97. Once we run the playbook we can see

[root@vx111a delegate]# ansible-playbook sample-playbook.yml

PLAY [cent] *******************************************************************

GATHERING FACTS ***************************************************************

ok: [172.16.202.96]

TASK: [Install zenity] ********************************************************

changed: [172.16.202.96]

TASK: [configure zenity] ******************************************************

changed: [172.16.202.96]

TASK: [Tell Master] ***********************************************************

changed: [172.16.202.96 -> 172.16.202.97]

PLAY RECAP ********************************************************************

172.16.202.96              : ok=4    changed=3    unreachable=0    failed=0  

Now check the remote machine 172.16.202.97 for the file created.

root@ubuntu:/home/vagrant# cat /tmp/list

dev.foohost.vm done

More to Come. Happy learning