Set Variable from Content of Text File?

[Resicow]

Hello Nginx Community, and Happy New Year...

Is it possible to set the value of a variable based on the contents of a 
text file?

So if there is site downtime, I can place a file in a directory that 
nginx will see and will know to serve a downtime notice, but then can 
nginx read the contents of the file to determine which downtime notice 
to serve?

Thanks,

John