As an **administrator**,
**I want** sudo passwords to be stored in ansible vaults,
**so that** I'm only required to provide the vault password to carry out server setup tasks.
Acceptance Criteria:
* Playbooks that provision multiple servers run without errors, even if there are different sudo passwords on each involved machine.
* The user `deploy` on the deployment machine has prepared password vault(s) for each machine in its working copy of the `fundraising-infrastructure` repository.
* The usage of the password vault(s) is documented in the `fundraising-infrastructure` repository.
Background:
* Almost all of the server setup playbooks use the role `backup_user`. It contains a task that sets the public SSH key of the backup user's as an authorized key on the backup server. If the passwords of the machines are not equal, the playbook fails to run. Thus, the playbooks can currently only be run if the machines share the same password.
* It seems that the necessary vaults for the machines/host "groups" are not known to the playbook/role, when using `delegate_to`.
* We need to work around the fact, that
** we might not want to use `host_vars/`
** the file names in `group_vars/` that are required by convention (`group_name.yml`) are already in use by other files defining non-secret variables.