Dump request headers seen by an application

I often come across issues where we need to inspect the request headers that an app services is receiving. Without code modifications its often difficult to achieve these results. On a Windows app services PHP is installed by default so we can simply use a PHP page to return the headers.

I added some additional lines that will write the headers to a file in case you do not want the client to see the headers.

$headers = apache_request_headers();
foreach ($headers as $header => $value) {
    echo "$header: $value <br />\n";
     //Write action to txt log
    $log  = $header.":".$value.PHP_EOL;
    file_put_contents('./headers.txt', $log, FILE_APPEND);
$log  = "-------------------------------------------------".PHP_EOL;
file_put_contents('./headers.txt', $log, FILE_APPEND);