Playbook tasks vs Role tasks

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1

I think I’m missing something fundamental.

I have a Playbook for doing Google Computer Engine (gce) stuff and it’s based on playbooks I found on the Internet. The tasks are defined within the playbook.

  • name: google compute engine testing
    hosts: localhost
    connection: localhost
    gather_facts: no

vars:
project_id: AAAA
instance_names: BBBB
service_account_email: me@AAAA.iam.gserviceaccount.com
credentials_file: CCCCC
image: ubuntu-1604-xenial-v20160721
machine_type: f1-micro
zone: us-central1-b

tasks:

  • name: create instance

gce:
instance_names: “{{ instance_names }}”
zone: “{{ zone }}”
machine_type: “{{ machine_type }}”
image: “{{ image }}”
project_id: “{{ project_id }}”
credentials_file: “{{ credentials_file }}”
service_account_email: “{{ service_account_email }}”
register: gce
tags: google

  • name: wait for ssh
    wait_for:
    host: “{{ item.public_ip }}”
    port: 22
    delay: 10
    timeout: 60
    state: started
    with_items: “{{ gce.instance_data }}”
    tags: google

How would I change this into a Role called gce-instance?

I assume the vars: and tasks would just move to the Role’s tasks/main.yml)?

But how do I get the below stuff into the Role?

  • name: google compute engine testing
    hosts: localhost
    connection: localhost
    gather_facts: no

Sample Playbook

  • hosts: all
    vars:
    pre_tasks:
    roles:
  • { role: gce-instance }

I do not understand what

  • name: google compute engine testing
    hosts: localhost
    connection: localhost
    gather_facts: no

does. Is it setting up defaults for the below tasks?

tasks:

gcloud compute machine-types list

gcloud compute images list

2

first of all:

connection: localhost

is wrong, you can omit it as the ‘implicit localhost’ already uses a local connection or use:

connection: local

So roles are meant to reuse tasks, even so you still need to setup target hosts, in the case of cloud modules that ‘target’ is normally localhost (target is where the module executes).

That is why you always need a play, as roles do not target hosts, just provide a set of tasks and resources to run.