Support 'uptime' in hostlist

[Oisov]

Background

A common task using Nivlheim is to log the uptime of a given host. Today this is a slightly cumbersome:

• Using files we can extract the information from the file UptimeSince.
• This information must then be parsed back into hostlist
• In addition it is cumbersome to sort based on this field based on the ISO formating 2021-12-13 12:04:45

Suggestion:

Introduce a new parameter and field called uptime

Example usage:

Obtain hosts which have been rebooted between 350 and 360 days ago in descending order

/api/v2/hostlist?fields=hostname,uptime>=350d,uptime<360d&uptimesort=-uptime

Path:

What I think is needed to make this work

• Figure out what the cleanest way to obtain the uptime is. Is UptimeSince the correct way or would who -b or uptime -s be better options to log?
• Implement similar logic as to lastseen in https://github.com/unioslo/nivlheim/blob/master/server/service/api_hostlist.go

[oyvindhagberg]

I agree, this is a good idea. We should implement this.