如何在ansible_playbook中覆盖主机变量

Question

I am new to anisble...

I want to make sure mongo is running on all the hosts with tag tag_role_mongo and node is running on tag_role_node

is it possible to override hosts variable

hosts: {{ item.tag_name }} 
  tasks:
   command: // check ps output {{ item.process_name }} 
with_items:
  - tag_name: tag_role_mongo
    process_name: "mongo"
  - tag_name: tag_role_node
    process_name: "node"

I am pretty sure, my syntax is not, correct, my question is it even possible to do such thing using a playbook. In all the playbook examples, hosts is fixed or can be overridden from command line using extra-args option.

Any examples would be very helpful

Answer 1

I'm not fully sure if I understand your question correctly but tags are not added on a host-level but on task-level - see the documentation . What you probably mean is to execute the same command for two different groups (mongo and node). For this you can just split your playbook in two parts:

hosts: mongo_hosts 
tasks:
  command: ...

hosts: node_hosts
tasks:
  command: ...

Not very nice but should solve the problem. You can also create a role and pass to this role just the process name you want to check for, so maintenance become easier.