Accessing facts for non-playbook hosts
In the earlier exercise, we launched the main playbook, which invokes all the other playbooks to configure the entire infrastructure. At times, we may just want to configure a portion of our infrastructure, in which case, we can just invoke the individual playbooks, such as lb.yml, www.yml, or db.yml. Let's try running the Ansible playbook just for the load balancers:
$ ansible-playbook -i customhosts lb.yml
Oops! It failed! Here is the snapshot of the snippet from the output:
Ansible exits with an error as it was not able to find a variable from the host, which is not part of the playbook anymore. Here is how Ansible behaves when it comes to magic variables:
- Ansible starts to gather facts while it runs the code on a host. These facts are then stored in the memory for the duration of the playbook run. This is the default behavior, and can be turned off.
- For host B to discover variables from host A, Ansible should have communicated with host A earlier...
