How to serve static content in Laravel 5 over https?

You can create something like ForceHttps middleware and than create condition for environment inside of it, like this:

public function handle($request, Closure $next)
{
    if (!\App::environment('local')) {
        \URL::forceSchema('https');
    }

    return $next($request);
}

Than add it to some route group or globally if you want.

NOTE: I would suggest to resolve this on your web server, not in Laravel

Just use asset() helper to generate asset's URL. It will use the current protocol.

Do NOT force assets to be loaded by https, unless they are sensitive (which is almost never the case). That would be an overhead, because you usually care more of safe website content than safe assets. In other words, if you accept loading http website, you most likely accept http assets. Instead, consider using middleware to redirect http to https on each non-safe request.

This is the middleware I'm using myself:

public function handle($request, Closure $next)
{
    if (!$request->secure()) {
        return redirect()->secure($request->getRequestUri());
    }

    return $next($request);
}

If you wish to use it, please remember to fire it BEFORE attaching any cookies, that is before Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse middleware.

I created app/Helpers/SiteHelpers.php containing a function that overrides the default asset() function.

<?php

/**
 * Overrides the default asset() method, which generates an asset path for the application.
 *
 * @param  string $path
 * @param  bool   $secure
 *
 * @return string
 */
function asset ($path, $secure = null) {
    if (Request::server('HTTP_X_FORWARDED_PROTO') == 'https' || Request::server('HTTPS') == 'on') {
        $secure = TRUE;
    }

    return app('url')->asset($path, $secure);
}

then added it on bootstrap/autoload.php above require __DIR__.'/../vendor/autoload.php'; so it would look like below:

require __DIR__.'/../app/Helpers/SiteHelpers.php';
require __DIR__.'/../vendor/autoload.php';

this is flexible depending on whether you are serving your static content on http or https