I have an inventory of hosts, and from them, one of the tasks should choose a leader by running a command on each until one of the machines produces an expected output (json value.)
I want some code to run on that leader to initialize it, and then I want some of the other roles to delegate some tasks to that leader.
Not sure how to do this?
Should I use dynamic inventory to analyze a group of hosts, and create a new group (can you run built_in.command in dynamic inventory? Should I write a role task that runs the identifying command on each host, capturing the result globally if it returns what I want (but then running on each host even if I have found my leader?)
Me either, but we have a role to bootstrap galara mysql and we just use the first host in a group
I thought that there might be a way to a custom facts (gather_facts) to all machines, and indicate leader/joiner status there, but I can’t get the data to stick.
I think the idea to register the leader status during a dedicated task like Matt said is the better move.
You got this module if you want to create dynamic group during play :
https://docs.ansible.com/ansible/latest/collections/ansible/builtin/add_host_module.html
And during gather_facts, you could add your own custom facts :
https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_vars_facts.html#adding-custom-facts
Bash script example returning json :
#!/bin/bash leader_status=$(curl http://127.0.0.1/leader_status) echo {\"leader\" : \"${leader_status}\"}sounds like the same idea. So you use
run_onceon a task?