[POWER] investigate on OFF service failures (ssh?)

[Jerome Canler]

• Start a Linux server
• Execute OFF command on this serverId

Observations:

• the server eventually shutdowns as expected. The API does respond only when the connection is lost (probably SSH service is stopped server-side by the shutdown process); it's logically considered as failure by cool-updown backend thus displayed as KO
• on server side, shutdown command exit code is null (?!)
• about 20 seconds elapsed between connection established and command result
• when testing in interactive way, in fact the shutdown command 'blocks' the shell until services are properly stopped

2|cud  | 2023-10-07T10:46:49.137Z - info: =>(...off-server...)
2|cud  | 2023-10-07T10:46:49.269Z - info: (off-server:0) Connected to host via SSH!
2|cud  | 2023-10-07T10:47:19.089Z - debug: (off-server:0) STDOUT:
2|cud  | 2023-10-07T10:47:19.091Z - debug: (off-server:0) STDERR: Password:
2|cud  | 2023-10-07T10:47:19.095Z - debug: (off-server:0) shutdown command exit code: null
2|cud  | 2023-10-07T10:47:19.097Z - error: (off-server:0) Could not connect to host via SSH! - "Password:"

Conclusions:

• ssh client should return command response as soon as it is executed
• solved when executing sudo process in background (-b option)