How do I give a CGI script permission to access Calendar? When I run my script from the command line I can use - am actually prompted to use -  System Preferences to add ssh-keygen-wrapper to be authorised to access the Calendar.

But when I run the script as a CGI program it is not authorised to access the Calendar - it is running as nobody and fails - and I don't know how to give the CGI-invoked script required permission.

A related question is even whether I should as giving nobody access to Calendar ... but that's a separate issue. 

[FYI]
macOS High Sierra
Python CGI script using an AppleScript to read Calendar events
The nobody user is non-interactive and doesn’t have calendars anyways. You will need to have some component (maybe another custom app/process) running as you to deliver the calendar info. 

You really have two options, one of which is very bad.

Firstly, you could have your CGI scripts run as you. This isn’t hard but super dangerous and not recommended.

Secondly, you can build what is essentially a calendar proxy. This could be another program (running as you) which ever five minutes reads the calendar data and writes it out to a file which nobody, the account, can read. You already seem to be familiar and working just fine with calendars so this shouldn’t be an issue, it’s just another script that you schedule with cron.

Another thing, though I’m really not sure if it will work for nobody, is that you can run sudo su nobody and then launch it. Since OSX knows that the PTTY is attached to your user session it will show the prompt there for you to accept. While you still won’t be able to access your users calendars, this trick is useful if you have to use these sorts of permissions as root whom also doesn’t a graphical session.