Provisioning a Journalist Workstation fails without the site-specific file

[nathandyer]

Description

As of the 2.6.0 release, and specifically with the changes here, it is now no longer possible to provision a Journalist Workstation drive with only the files described in our documentation.

Steps to Reproduce

1. Follow the procedure to copy the required files for a Journalist Tails USB
2. Run the ./securedrop-admin tailsconfig command
3. Command fails due to the missing site-specific file, which is only present on Admin Workstations

Expected Behavior

The ./securedrop-admin tailsconfig runs correctly without error

Actual Behavior

./securedrop-admin tailsconfig returns an error due to the missing site-specific file

Comments

We may want to consider adjusting our QA procedures, to include a Journalist Workstation provisioning step (which likely would have caught this earlier)

[zenmonkeykstop]

AFAICT this code was added several years back, not in 2.6.0, and there's a check in the main.yml for this role to only create ssh aliases if the file does exist, so it's not immediately clear why it's failing now.

[cfm]

@zenmonkeykstop, this prompts me to revise the initial interpretation I offered @nathandyer yesterday:

1. https://github.com/freedomofpress/securedrop/blame/32d6fcec91d8a2ee2d33d5df64645ab6efc2a62b/install_files/ansible-base/roles/tails-config/tasks/create_ssh_aliases.yml#L2-L3 is old (v0.7.0) but runs on Admin Workstations only, to provision configure SSH.
2. https://github.com/freedomofpress/securedrop/blame/32d6fcec91d8a2ee2d33d5df64645ab6efc2a62b/install_files/ansible-base/roles/tails-config/tasks/install_shell_extension.yml#L2-L3 is new (v2.6.0) and runs on both Admin and Journalist Workstations, to configure the GNOME Shell extension, including SSH.

(2)'s bf20c4f imports the app_hostname and monitor_hostname variables from site-specific rather than reading them directly out of that file, which would have had to present in any case.

However, you could make the case that install_shell_extension doesn't need to know the {app,monitor}_hostnames, since:

1. on Admin Workstations, it could just hard-code ssh {app,mon} and let the SSH aliases configured by create_ssh_aliases do the trick; and
2. on Journalist Workstations, these menu items aren't present at all.

In other words, bf20c4f was maybe a different spelling of something we don't need after all.