In Ansible, how to exit with sucess if any host is unreachable (without using ignore_unreachable)

Question

I have the following playbook to get the first reachable host.

---
- hosts: all
  gather_facts: yes
  ignore_unreachable: yes

  tasks:

  - name: Get the first good host in the group
    vars:
      query: "[?ansible_facts!=''].inventory_hostname"
    set_fact:
      first_good_host: "{{ ansible_play_hosts | map('extract', hostvars) | list | json_query(query) | first }}"
    delegate_to: localhost  
    run_once: yes

  - name: Aggregate the first good host to reachable group
    ansible.builtin.add_host:
      name: '{{ first_good_host }}'
      groups: 'reachable'
    run_once: yes

  - name: print reachable hosts
    debug:
      msg: "{{ groups['reachable'] }}"

But this playbooks exists with 4 if there is any unreachable host(s). If I pass ignore_unreachable: true, then it exits with 0 but reachable also contains the unreachable host(s), which is what I don't want to.

I have also tried with any_errors_fatal and max_failure_percentage but no luck. I don't want to abort/fail on any unreachable host.

How can I deal with exit code 4 without using ignore_unreachable: true?

Playbook ref: Skip other hosts if first host is reachable in Ansible

Answer 1

ansible_play_hosts variable already contains only the list of valid reachable hosts of your play. Failed/Unreachable hosts are excluded from this list. Thus, you don't need to create a special custom variable to list only reachable hosts. If you need a list with all hosts including unreachable, you can use ansible_play_hosts_all. It contains the list of all the hosts that were targeted by the play.

Answer 2

If I pass ignore_unreachable: true, then it exits with 0 but reachable also contains the unreachable host(s), which is what I don't want to.

With a minimal example playbook

---
- hosts: all
  gather_facts: true
  ignore_unreachable: true

  tasks:

  - name: Get the first good host in the group
    set_fact:
      first_good_host: "{{ ansible_play_hosts | map('extract', hostvars) | list | json_query(query) | first }}"
    vars:
      query: "[?ansible_facts!=''].inventory_hostname"
    delegate_to: localhost
    run_once: yes

  - name: Aggregate the first good host to reachable group
    ansible.builtin.add_host:
      name: '{{ first_good_host }}'
      groups: 'reachable'

- hosts: "{{ groups['reachable'] }}"

  tasks:

  - name: Print reachable hosts
    debug:
      msg: "{{ ansible_play_hosts }}"

I am not able reproduce that

... also contains the unreachable host(s) ...

The dynamic group reachable will only contain the first reachable host resulting into an output of

PLAY [all] *****************************************************************************************************

TASK [Gathering Facts] *****************************************************************************************
ok: [test2.example.com]
ok: [test1.example.com]
fatal: [test3.example.com]: UNREACHABLE! => changed=false
  msg: 'Failed to connect to the host via ssh: ssh: connect to host test3.example.com port 22: No route to host'
  skip_reason: Host test3.example.com is unreachable
  unreachable: true

TASK [Get the first good host in the group] ********************************************************************
ok: [test1.example.com -> localhost]

TASK [Aggregate the first good host to reachable group] ********************************************************
changed: [test1.example.com]

PLAY [[u'test1.example.com']] **********************************************************************************

TASK [Gathering Facts] *****************************************************************************************
ok: [test1.example.com]

TASK [Print reachable hosts] ***********************************************************************************
ok: [test1.example.com] =>
  msg:
  - test1.example.com

PLAY RECAP *****************************************************************************************************
test1.example.com: ok=5    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0 
test2.example.com: ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
test3.example.com: ok=0    changed=0    unreachable=1    failed=0    skipped=1    rescued=0    ignored=0

and if called via

ansible-playbook unreachable.yml; echo $?
0

Removing the line

  ignore_unreachable: true

would result into

ansible-playbook unreachable.yml; echo $?
4

Please take note of the other answer here and Playbook execution.

---

But this playbooks exists with 4 if there is any unreachable host(s). (annot.: ... and without using ignore_unreachable: true)

Right, that is the expected behavior.

How can I deal (annot.: avoid?) with exit code 4 without using ignore_unreachable: true?

You can't avoid it since that Return / Exit Code is provided from the ansible-playbook command itself at the very end of the run, not from within the playbook and as far as I understand. Usually I am not linking external content, but in this case you may have a look into Ansible Exit Codes.

Furthermore you might also take advantage from What is the XY problem.