How to iterate environment variables in ansible?

Question

In this playbook

# db.yml

- hosts: deploy-server
  become: True
  roles:
    - db
  environment:
    PGHOST: "{{ db_host }}"
    PGPASSWORD: "{{ db_pass }}"

In db roles

# roles/db/tasks/main.yml

- name: Run sql
  shell: "psql -U postgres -f /sql"

I want to deploy the same sql script to multiple db servers.

For example, use these variables:

• db_host1
• db_host2
• ...

Not by ssh but using psql. So is it possible to loop the PGHOST variable to set dynamic list to use?

Answer 1

Q: "Is it possible to loop the PGHOST variable?"

A: Yes. It is possible. Set the environment variable in the loop, e.g.

- hosts: localhost
  tasks:
    - command: "echo $PGHOST"
      register: result
      loop: [db_host1, db_host2]
      environment:
        PGHOST: "{{ item }}"
    - debug:
        msg: "{{ result.results|json_query('[].stdout') }}"

gives

  msg:
  - db_host1
  - db_host2

---

If you want to apply various environment to a role iterate include_role and apply the environment, e.g. the role

shell> cat roles/db/tasks/main.yml 
- command: "echo $PGHOST"
  register: result
- debug:
    var: result.stdout

and the playbook

shell> cat pb.yml
- hosts: localhost
  tasks:
    - include_role:
        name: db
        apply:
          environment:
            PGHOST: "{{ item }}"
      loop: [db_host1, db_host2]

give

...

TASK [include_role : db] ***********************************************

TASK [db : command] ****************************************************
changed: [localhost]

TASK [db : debug] ******************************************************
ok: [localhost] => 
  result.stdout: db_host1

TASK [db : command] ****************************************************
changed: [localhost]

TASK [db : debug] ******************************************************
ok: [localhost] => 
  result.stdout: db_host2

...