I'm setting up an Ansible playbook to set up a couple servers. There are a couple of tasks that I only want to run if the current host is my local dev host, named "local" in my hosts file. How can I do this? I can't find it anywhere in the documentation.
I've tried this when statement, but it fails because ansible_hostname resolves to the host name generated when the machine is created, not the one you define in your hosts file.
- name: Install this only for local dev machine
pip:
name: pyramid
when: ansible_hostname == "local"
The necessary variable is inventory_hostname.
- name: Install this only for local dev machine
pip:
name: pyramid
when: inventory_hostname == "local"
It is somewhat hidden in the documentation at the bottom of this section.
You can limit the scope of a playbook by changing the hosts header in its plays without relying on your special host label ‘local’ in your inventory. Localhost does not need a special line in inventories.
- name: run on all except local
hosts: all:!local
This is an alternative:
- name: Install this only for local dev machine
pip: name=pyramid
delegate_to: localhost
Related
I'm having two machines one is the ansible controller where I execute my playbooks from and the other one is the remote machine (target) which I would like to install/update. The important thing is that the controller runs within the corporate network but the target is outside that network (only accessible via ssh).
So I need to download a file (from within the corporate network) and copy it to the target node.
I've tried to use: ansible.builtin.get_url to download the file but
unfortunately it will do that on the remote (target) machine which has of course no access to the corporate network.
Does someone has a tip/idea ?
Update: Using ansible [core 2.11.6]
To download something to the local Ansible Controller you may use the following approach.
- name: Download something to Ansible Controller
delegate_to: localhost
get_url:
url: "https://{{ ansible_user }}:{{ ansible_password }}#files.example.com/installer.rpm"
dest: "/tmp/{{ ansible_user }}"
owner: "{{ ansible_user }}"
tags: download,local
Please take note that according Controlling where tasks run: delegation and local actions, delegate_to is not a parameter of module get_url but of the task.
Use-Case:
Playbook 1
when we first connect to a remote host/s, the remote host will already have some python version installed - the auto-discovery feature will find it
now we install ansible-docker on the remote host
from this time on: the ansible-docker docs suggest to use ansible_python_interpreter=/usr/bin/env python-docker
Playbook 2
We connect to the same host/s again, but now we must use the /usr/bin/env python-docker python interpreter
What is the best way to do this?
Currently we set ansible_python_interpreter on the playbook level of Playbook 2:
---
- name: DaqMon app
vars:
- ansible_python_interpreter: "{{ '/usr/bin/env python-docker' }}"
This works, but this will also change the python interpreter of the local actions. And thus the local actions will fail, because (python-docker does not exist locally).
the current workaround is to explicitly specify the ansible_python_interpreter on every local-action which is tedious and error-prone
Questions:
the ideal solution is, if we could add '/usr/bin/env python-docker' as fallback to interpreter-python-fallback - but I think this is not possible
is there a way to set the python interpreter only for the remote hosts - and keep the default for the localhost?
or is it possible to explicitly override the python interpreter for the local host?
You should set the ansible_python_interpreter on the host level.
So yes, it's possible to explicitly set the interpreter for localhost in your inventory.
localhost ansible_connection=local ansible_python_interpreter=/usr/bin/python
And I assume that you could also use set_fact on hostvars[<host>].ansible_python_interpreter on your localhost or docker host.
There is a brillant article about set_fact on hostvars ! ;-P
Thanks to the other useful answers I found an easy solution:
on the playbook level we set the python interpreter to /usr/bin/env python-docker
then we use a set_fact task to override the interpreter for localhost only
we must also delegate the facts
we can use the magic ansible_playbook_python variable, which refers to the python interpreter that was used on the (local) Ansible host to start the playbook: see Ansible docs
Here are the important parts at the start of Playbook 2:
---
- name: Playbook 2
vars:
- ansible_python_interpreter: "{{ '/usr/bin/env python-docker' }}"
...
tasks:
- set_fact:
ansible_python_interpreter: '{{ ansible_playbook_python }}'
delegate_to: localhost
delegate_facts: true
Try to use set_fact for ansible_python_interpreter at host level in the first playbook.
Globally, use the interpreter_python key in the [defaults] section of the ansible.cfg file.
interpreter_python = auto_silent
I am writing a playbook where i need to select host which will be a part of group which starts with name "hadoop". The host will be supplied as an extra variable in term of parent group. The task is about upgrading the java on all machines with repo but there are certain servers which dont have repo configured or are in dmz and can only use there local repo... i need to enable local_rpm:true so that when the playbook execute the server which belong to hadoop group have this fact enabled.
I tried like below :
- hosts: '{{ target }}'
gather_facts: no
become: true
tasks:
- name: enable local rpm
set_fact:
local_rpm: true
when: "'hadoop' in group_names"
tags: always
and then importing my role based on tag
It's probably better to use group_vars in this case.
https://docs.ansible.com/ansible/latest/user_guide/intro_inventory.html#group-variables
I'm setting up an Ansible playbook to set up a couple servers. There are a couple of tasks that I only want to run if the current host is my local dev host, named "local" in my hosts file. How can I do this? I can't find it anywhere in the documentation.
I've tried this when statement, but it fails because ansible_hostname resolves to the host name generated when the machine is created, not the one you define in your hosts file.
- name: Install this only for local dev machine
pip:
name: pyramid
when: ansible_hostname == "local"
The necessary variable is inventory_hostname.
- name: Install this only for local dev machine
pip:
name: pyramid
when: inventory_hostname == "local"
It is somewhat hidden in the documentation at the bottom of this section.
You can limit the scope of a playbook by changing the hosts header in its plays without relying on your special host label ‘local’ in your inventory. Localhost does not need a special line in inventories.
- name: run on all except local
hosts: all:!local
This is an alternative:
- name: Install this only for local dev machine
pip: name=pyramid
delegate_to: localhost
I would like to insert an IP address in to a J2 template which is used by an Ansible playbook. That IP adress is not the address of the host which is being provisioned, but the IP of the host from which the provisioning is done. Everything I have found so far covers using variables/facts related to the hosts being provisioned.
In other words: the IP I’d like to insert is the one in ['ansible_default_ipv4']['address'] when executing ansible -m setup 127.0.0.1.
I think that I could use a local playbook to write a dynamically generated template file containing the IP, but I was hoping that this might be possible “the Ansible way”.
Just use this:
{{ ansible_env["SSH_CLIENT"].split()[0] }}
You can force Ansible to fetch facts about the control host by running the setup module locally by using either a local_action or delegate_to. You can then either register that output and parse it or simply use set_fact to give it a useful name to use later in your template.
An example play might look something like:
tasks:
- name: setup
setup:
delegate_to: 127.0.0.1
- name: set ansible control host IP fact
set_fact:
ansible_control_host_address: "{{ hostvars[inventory_hostname]['ansible_eth0']['ipv4']['address'] }}"
delegate_to: 127.0.0.1
- name: template file with ansible control host IP
template:
src: /path/to/template.j2
dest: /path/to/destination/file
And then use the ansible_control_host_address variable in your template as normal:
...
Ansible control host IP: {{ ansible_control_host_address }}
...
This is how I solved the same problem (Ansible 2.7):
- name: Get local IP address
setup:
delegate_to: 127.0.0.1
delegate_facts: yes
- name: Add to hosts file
become: yes
lineinfile:
line: "{{ hostvars['127.0.0.1']['ansible_default_ipv4']['address'] }} myhost"
path: /etc/hosts
Seems to work like a charm. :-)