Using cURL and the host header to bypass a load balancer
Users are reporting that when they load the site they're occasionally seeing stale content. We have multiple app servers behind a load balancer so my suspicion is that one server isn't expiring content correctly so depending on which one you get you'll see different data. To test this I want to write a simple script to connect to each server save the results and then compare them for differences.
The main problem to tackle is that if I try to connect to www.example.com I'll be connecting to the load balancer and then handed off to a random server. I want to connect directly to each server servers so I'll need to use their IP address. This approach would look something like:
curl --verbose 'http://10.1.1.36:8000/the_url_to_test'But since the servers use name-based virtual hosts so we'd get a 404 error back. The trick is to have curl send the proper host header:
curl --verbose --header 'Host: www.example.com' 'http://10.1.1.36:8000/the_url_to_test'This gives us the output we need to start writing the comparison script.
Using PHP and CURL to do an HTML file POST
After scouring the internet to find out how to do multipart post operations and finding nothing nothing, I decided to save someone else some time. The trick is that @ before the file name:
<?php
$fullflepath = 'C:\temp\test.jpg';
$upload_url = 'http://www.example.com/uploadtarget.php';
$params = array(
'photo'=>"@$fullfilepath",
'title'=>$title
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_VERBOSE, 1);
curl_setopt($ch, CURLOPT_URL, $upload_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $params);
$response = curl_exec($ch);
curl_close($ch);
?>Originally posted here: http://drewish.com/blogger/archives/2005/01/27/using_php_and_curl_to_do_...
Enabling PHP Modules
Phlickr uses two several of PHP5's extensions, CURL and SimpleXML. In some cases these two extensions may not be enabled by default.
The first step is verify that the modules are not already being loaded. You view a list of the modules using the following command:
Downloading Democracy Now! automatically
Here's a PHP script I wrote for the radio station to download each day's copy of Democracy Now!. This requires that the PHP cURL extension be installed.
