librenms-librenms/app/Plugins/ExamplePlugin/PortTab.php

<?php

namespace App\Plugins\ExamplePlugin;

use App\Plugins\Hooks\PortTabHook;

// this will insert a tab into every port view
class PortTab extends PortTabHook
{
    // point to the view for your plugin's port plugin
    // this is the default name so you can create the blade file as in this plugin
    // by ommitting the variable, or point to another one

//    public string $view = 'resources.views.port-tab';

    // override the data function to add additional data to be accessed in the view
    // title is a required attribute and will be shown above your returned html from your blade file
    // inside the blade, all variables will be named based on the key in the returned array
    public function data(\App\Models\Port $port): array
    {
        // run any calculations here
        $total_delta = $port->ifOutOctets_delta + $port->ifInOctets_delta; // nonsense calculation :)

        return [
            'title' => 'Example Plugin',
            'port' => $port,
            'something' => 'this is a variable and can be accessed with {{ $something }}',
            'total' => $total_delta,
        ];
    }

    // The authorize method will determine if the user will see this tab or not
    // if you want all users to see it, simple return true
    public function authorize(\Illuminate\Contracts\Auth\Authenticatable $user, \App\Models\Port $port): bool
    {
        // you can check user's roles like this:
//        return $user->can('admin');

        // or use whatever you like. Including conditions on the \App\Models\Port $port of course
//        return \Carbon\Carbon::now()->dayOfWeek == Carbon::THURSDAY; // only allowed access on Thursdays!

        return true; // allow every logged in user to access
    }
}