Get current hostname and push it into conf file with ansible

Question

I'm working into an ansible playbook to get the current hostname of a server and then set it into a configuration file. I cannot figure it out how can I push the shell output using the lineinfile module.

  - name: Get hostname
    shell: echo $HOSTNAME
    register: result

  - name: Set hostname on conf file
    lineinfile: dest=/etc/teste/linux/zabbix_agentd.conf regexp="^Hostname=.*" insertafter="^# Hostname=" line=Hostname=????

Answer 1

In general, to look what's inside a variable you can use the debug module.

- debug:
    var: result

This should show you an object and its properties which include stdout. That is the complete result of the previous command. So to use the output of the first task you would use result.stdout.

To use any variable you would use Jinja2 expressions: {{ whatever }}. So your task could look like this:

- name: Set hostname on conf file
  lineinfile:
    dest: /etc/teste/linux/zabbix_agentd.conf
    regexp: ^Hostname=.*
    insertafter: ^# Hostname=
    line: Hostname={{ result.stdout }}

---

So much for theory, but here comes the real answer. Don't do it like that. Of course Ansible already knows the hostname.

The hostname as defined in your inventory would be {{ inventory_hostname }}. The hostname as reported by the server is {{ ansible_hostname }}. Additionally there is {{ ansible_fqdn }}. So just use any of these instead of running an additional task:

- name: Set hostname on conf file
  lineinfile:
    dest: /etc/teste/linux/zabbix_agentd.conf
    regexp: ^Hostname=.*
    insertafter: ^# Hostname=
    line: Hostname={{ ansible_hostname }}

Answer 2

You should pass variables in the command line.

First, register the variable

---
- hosts: 127.0.0.1
  connection: local
  vars:
  - person: John Snow
  - filename: v1.j2
  vars_files:
  - vars.yml
  tasks:
  - name: Who I am?
    action: command /usr/bin/whoami
    register: myname
  - name: Run jpprog.sh
    action: command ./jpprog.sh
    register: v

  - name: Populate template
    action: template src={{filename}} dest=/tmp/out

This playbook runs two commands: the first stores its output in a variable called myname, and the second in a variable v. The result of whoami is a single string which is made available to the template as variablename.stdout. The result of jpprog.sh is a JSON object represented as a string:

{
    "number": 18,
    "name": "john"
}

The template follows:

-> I am {{ myname.stdout }}

{% set t = v.stdout|from_json %}

JSON struct T: {{ t }}

name = {{ t.name }} 
number = {{ t['number'] }}

and the output is:

-> I am jpm

JSON struct T: {u'number': 18, u'name': u'john'}

name = john 
number = 18

Source:Jan-Piet Mens web site.

Answer 3

- name: Set hostname on conf file
  command: sed -i s/whatComesAfterHostname=/{{ ansible_hostname }}/g /etc/teste/linux/zabbix_agentd.conf

worked for me.