Install libplack-middleware-header-perl by entering the following commands in the terminal:
sudo apt update sudo apt install libplack-middleware-header-perl
Plack middleware to modify HTTP response headers
Plack is a set of tools similar to Ruby's Rack or Python's Paste for WSGI. It implements the Perl Server Gateway Interface (PSGI) standard interface, which allows developers to decouple their web application framework from the local web server environment. . Plack::Middleware::Header allows modification (setting, appending to, and unsetting) of HTTP response headers.