Abort further task execution, with multiple hosts

Question

Using Ansible v2.9.12

Question: I'd like Ansible to fail/stop the play when a task fails, when multiple hosts execute the task. In that sense, Ansible should abort the task from further execution. The configuration should work in a role, so using serial, or using different plays, is not possible.

Example ;

- hosts:
    - host1
    - host2
    - host3
  any_errors_fatal: true
  tasks:
    - name: always fail
      shell: /bin/false
      throttle: 1

Provides ;

===== task | always fail =======
host1: fail
host2: fail
host3: fail

Meaning, the task is still executed on the second host and third host. I'd desire the whole play to fail/stop, once a task fails on a host. When the task fails on the last host, Ansible should abort as well.

Desired outcome ;

===== task | always fail =======
host1: fail
host2: not executed/skipped, cause host1 failed
host3: not executed/skipped, cause host1 failed

As you can see, I've fiddled around with error handling, but without prevail.

Background info: I've been developing an idempotent Ansible role for mysql. It is possible to setup a cluster with multiple hosts. The role also supports adding an arbiter.

The arbiter does not has the mysql application installed, but the host is still required in the play.

Now, imagine three hosts. Host1 is the arbiter, host2 and host3 have mysql installed, setup in a cluster. The applications are setup by the Ansible role. Now, Ansible executes the role for a second/third/fourth/whatever time, and changes a config setting of mysql. Mysql needs a rolling restart. Usually, one writes some thing along the lines of:

- template:
    src: mysql.j2
    dest: /etc/mysql
  register: mysql_config
  when: mysql.role != 'arbiter'

- service:
    name: mysql
    state: restarted
  throttle: 1
  when:
    - mysql_config.changed
    - mysql.role != 'arbiter'

The downside of this Ansible configuration, is that if mysql fails to start on host2 due to whatever reason, Ansible will also restart mysql on host3. And that is undesired, because if mysql fails on host3 as well, then the cluster is lost. So, for this specific task I'd like Ansible to stop/abort/skip other tasks if mysql has failed to start on a single host in the play.

Kevin C Kevin C · Accepted Answer · 2020-09-08T20:41:42

Ok, this works:

# note that test-multi-01 set host_which_is_skipped: true
---
- hosts:
    - test-multi-01
    - test-multi-02
    - test-multi-03
  tasks:
    - set_fact:
        host_which_is_skipped: "{{ inventory_hostname }}"
      when: host_which_is_skipped

    - shell: /bin/false
      run_once: yes
      delegate_to: "{{ item }}"
      loop: "{{ ansible_play_hosts }}"
      when:
        - item != host_which_is_skipped
        - result is undefined or result is not failed
      register: result

    - meta: end_play
      when: result is failed

    - debug:
        msg: Will not happen

When the shell command is set to /bin/true, the command is executed on host2 and host3.

Abort further task execution, with multiple hosts

3 Answers