Passing variables between nested playbooks

Question

I have a playbook where I'm spinning up an instance in aws with the ec2 module. To be more flexible I ask via prompt for the hostname. I found in the ec2 examples the code snippet, which allows you to run a second playbook with newly spun up instance for further configuration.

Now I want to set the hostname via module hostname but I cannot access the variable in the second playbook.

This is how my playbook looks like:

---
- hosts: localhost
  ...

  vars_prompt:
    - name: var_hostname
      prompt: "Please enter the hostname"
      private: no

  tasks:

    - name: Spin up instance
      local_action:
        module: ec2
        ...
      register: ec2

    - name: Add new instance to host group
      add_host: hostname={{ item.public_ip }} groupname=launched
      with_items: ec2.instances

- hosts: launched
  ...

  tasks:

    - name: Set hostname
      hostname: name="{{ var_hostname }}"

fatal: [launched] => One or more undefined variables: 'var_hostname' is undefined

Is there a way to pass a variable from one playbook to another one?

I found Ansible best practice for passing vars to nested playbooks? but unfortunately it didn't had a solution which I can use.

Possible duplicate of **[How do I set register a variable to persist between plays in ansible?](http://stackoverflow.com/questions/33896847/how-do-i-set-register-a-variable-to-persist-between-plays-in-ansible)** — Felipe Alvarez, May 10 '17 at 02:28
In this particular case, it's more efficient to put the variables into the parameters of the module *add_host*. — Vladimir Botka, Jun 27 '22 at 05:05

score 7 · Answer 1 · answered Nov 27 '15 at 13:49

7

You can use set_fact and hostvars together to achieve what you want.

Do set_fact on one group of hosts( i.e localhost), and access them in a different play using hostvars

{{hostvars['localhost']["new_fact"]}}

answered Nov 27 '15 at 13:49

vangap

243
5
12

2

This works, a full playbook example in the answer would be most useful. – TeTeT Nov 17 '16 at 12:01
A full working example is here - http://stackoverflow.com/questions/33896847/how-do-i-set-register-a-variable-to-persist-between-plays-in-ansible – Hrishikesh Kumar Feb 13 '17 at 07:42

score 5 · Answer 2 · answered Nov 26 '15 at 19:50

You can use local files.

1) Write

- name: write public ip
  local_action:
    template:
      dest: /tmp/ansible_master_public_ip.txt
      src: templates/public_ip.j2

2) Retrieve with http://docs.ansible.com/ansible/playbooks_lookups.html

hostname: "{{ lookup('file', '/tmp/ansible_master_public_ip.txt') | trim }}"

PS. Ini file lookup also an option if you need more than few variables.

score 0 · Answer 3 · answered Jun 27 '22 at 05:01

Add the host's variable to the parameters. For example,

    - name: Add new instance to host group
      add_host:
        hostname: "{{ ec2.instances.0.public_ip }}"
        groupname: launched
        var_hostname: "{{ var_hostname }}"

See examples
Use only the first item from the list because you have only one hostname. There is no reason to iterate the list.

^{Example of a complete playbook for testing
- hosts: localhost
gather_facts: false
vars_prompt:
- name: var_hostname
prompt: "Please enter the hostname"
private: no
vars:
ec2:
instances:
- public_ip: AAA.BBB.CCC.DDD
tasks:
- name: Add new instance to host group
add_host:
hostname: "{{ ec2.instances.0.public_ip }}"
groupname: launched
var_hostname: "{{ var_hostname }}"

- hosts: launched
gather_facts: false
tasks:
- debug:
var: var_hostname

shell> ansible-playbook pb.yml
Please enter the hostname: host_2

PLAY [localhost] *****************************************************************************

TASK [Add new instance to host group] ********************************************************
changed: [localhost]

PLAY [launched] ******************************************************************************

TASK [debug] *********************************************************************************
ok: [AAA.BBB.CCC.DDD] =>
var_hostname: host_2

PLAY RECAP ***********************************************************************************
AAA.BBB.CCC.DDD: ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
localhost : ok=1 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0}

Use pause instead of vars_prompt if you have more hosts. For example,

    - name: Get var_hostname(s)
      pause:
        prompt: "Please enter the hostname for {{ item.public_ip }}"
        echo: yes
      loop: "{{ ec2.instances }}"
      register: var_hostnames
    - name: Add new instances to host group
      add_host:
        hostname: "{{ item.item.public_ip }}"
        groupname: launched
        var_hostname: "{{ item.user_input }}"
      loop: "{{ var_hostnames.results }}"
      loop_control:
        label: "{{ item.user_input }}"

^{Example of a complete playbook for testing
- hosts: localhost
gather_facts: false
vars:
ec2:
instances:
- public_ip: AAA.BBB.CCC.DD1
- public_ip: AAA.BBB.CCC.DD2
tasks:
- name: Get var_hostname(s)
pause:
prompt: "Please enter the hostname for {{ item.public_ip }}"
echo: yes
loop: "{{ ec2.instances }}"
register: var_hostnames
- name: Add new instances to host group
add_host:
hostname: "{{ item.item.public_ip }}"
groupname: launched
var_hostname: "{{ item.user_input }}"
loop: "{{ var_hostnames.results }}"
loop_control:
label: "{{ item.user_input }}"

- hosts: launched
gather_facts: false
tasks:
- debug:
var: var_hostname

shell> ansible-playbook pb.yml

PLAY [localhost] *****************************************************************************

TASK [Get var_hostname(s)] *******************************************************************
[Get var_hostname(s)]
Please enter the hostname for AAA.BBB.CCC.DD1:
host_1^Mok: [localhost] => (item={'public_ip': 'AAA.BBB.CCC.DD1'})
[Get var_hostname(s)]
Please enter the hostname for AAA.BBB.CCC.DD2:
host_2^Mok: [localhost] => (item={'public_ip': 'AAA.BBB.CCC.DD2'})

TASK [Add new instances to host group] *******************************************************
ok: [localhost] => (item=host_1)
ok: [localhost] => (item=host_2)

PLAY [launched] ******************************************************************************

TASK [debug] *********************************************************************************
ok: [AAA.BBB.CCC.DD1] =>
var_hostname: host_1
ok: [AAA.BBB.CCC.DD2] =>
var_hostname: host_2

PLAY RECAP ***********************************************************************************
AAA.BBB.CCC.DD1: ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
AAA.BBB.CCC.DD2: ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
localhost : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0}

Passing variables between nested playbooks

3 Answers3