How to do it...

1. Create a new file called decrypt_passwd as shown:

$ echo 'strong_password' > decrypt_passwd

2. Using ansible-vault creates a new file called secrets, as shown here:

$ ansible-vault create --vault-id=decrypt_passwd secrets

3. Add the following variables to this new secrets file:

ospf_password: ospf_P@ssw0rD
bgp_password: BGP_p@ssw0rd

4. Create a new playbook called ansible_vault.yml, as shown here:

---
  - name: Using Ansible vault
    hosts: all
    gather_facts: no
    vars_files:
      - secrets
    tasks:
      - name: Output OSPF passowrd
        debug:
          msg: "Router {{ hostname }} ospf Password {{ ospf_password }}"
        when: inventory_hostname == 'csr1'

      - name: Output BGP passowrd
        debug:
          msg: "Router {{ hostname }} BGP Password {{ bgp_password }}"
        when: inventory_hostname == 'mx1'

5. Run the playbook as shown here:

$ ansible-playbook --vault-id=decrypt_passwd ansible_vault.yml -i hosts