FreeKB - Ansible ansible_hostname magic variable
Ansible - ansible_hostname magic variable

There are a number of different magic variable will return the hostname of a managed node (e.g. the target systems).

Or, the lookup pipe hostname plugin can be used to return the hostname of your control node (that's your Ansible server). 

For example, let's say you have the following playbook. 

---
- hosts: all
  tasks:
    - debug:
        msg: ansible_hostname = {{ ansible_hostname }}

    - debug:
        msg: ansible_play_batch = {{ ansible_play_batch }}

    - debug:
        msg: ansible_play_hosts_all = {{ ansible_play_hosts_all }}

    - debug:
        msg: ansible_limit = {{ ansible_limit }}

    - debug:
        msg: inventory_hostname = {{ inventory_hostname }}

    - debug:
        msg: inventory_hostname_short = {{ inventory_hostname_short }}

    - debug:
        msg: play_hosts = {{ play_hosts }}

 

Since the ansible_hostname will return the hostname from facts, gather_facts must be true. If gather_facts is false, something like this will be returned.

TASK [debug] 
fatal: [server1.example.com]: FAILED! => {"msg": "The task includes an option with an undefined variable.
The error was: 'ansible_hostname' is undefined\n\n
The error appears to be in '/home/john.doe/testing.yml': line 18, column 7, but may\n
be elsewhere in the file depending on the exact syntax problem.\n\n
The offending line appears to be:\n\n
  tasks:\n
    - debug:\n
      ^ here\n"}

 

Assuming gather_facts is true, running this playbook should return something like this.

TASK [debug]
ok: [server1.example.com] => {
    "msg: "ansible_hostname = server1"
}
ok: [server2.example.com] => {
    "msg: "ansible_hostname = server2"
}
ok: [server3.example.com] => {
    "msg: "ansible_hostname = server3"
}

TASK [debug]
ok: [server1.example.com] => {
    "msg": [
        "server1.example.com",
        "server2.example.com",
        "server3.example.com"
    ]
}

TASK [debug]
ok: [server1.example.com] => {
    "msg": [
        "server1.example.com",
        "server2.example.com",
        "server3.example.com"
    ]
}

TASK [debug]
ok: [server1.example.com] => {
    "msg: "ansible_limit = server1.example.com"
}

TASK [debug]
ok: [server1.example.com] => {
    "msg: "inventory_hostname = server1.example.com"
}
ok: [server2.example.com] => {
    "msg: "inventory_hostname = server2.example.com"
}
ok: [server3.example.com] => {
    "msg: "inventory_hostname = server3.example.com"
}

TASK [debug]
ok: [server1.example.com] => {
    "msg: "inventory hostname_short = server1"
}
ok: [server2.example.com] => {
    "msg: "inventory hostname_short = server3"
}
ok: [server3.example.com] => {
    "msg: "inventory hostname_short = server3"
}

TASK [debug]
ok: [server1.example.com] => {
    "msg: "play_hosts = ['server1.example.com', 'server2.example.com', 'server3.example.com']"
}
ok: [server2.example.com] => {
    "msg: "play_hosts = ['server1.example.com', 'server2.example.com', 'server3.example.com']"
}
ok: [server3.example.com] => {
    "msg: "play_hosts = ['server1.example.com', 'server2.example.com', 'server3.example.com']"
}

 



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