During some migration operations on a Drupal 8 site, I needed to make an HTTP request that took > 30 seconds to return all the data... and when I ran the migration, I'd end up with exceptions like:

Migration failed with source plugin exception: Error message: cURL error 28: Operation timed out after 29992 milliseconds with 2031262 out of 2262702 bytes received (see https://curl.haxx.se/libcurl/c/libcurl-errors.html).

The solution, it turns out, is pretty simple! Drupal's \Drupal\Core\Http\ClientFactory is the default way that plugins like Migrate's HTTP fetching plugin get a Guzzle client to make HTTP requests (though you could swap things out if you want via services.yml ), and in the code for that factory, there's a line after the defaults (where the 'timeout' => 30 is defined) like:

<code>
<?php
$config = NestedArray::mergeDeep($default_config, Settings::get('http_client_config', []), $config);
?>
</code>

Seeing that, I know at a glance that Drupal is pulling any http_client_config configuration overrides from settings.php and applying them to the Guzzle Clients that this factory creates. Therefore, I can add the following to my site's settings.php to set the default timeout to 60 seconds instead of the default 30 :

<code>
<?php
/**
 * HTTP Client config.
 */
$settings['http_client_config']['timeout'] = 60;
?>
</code>

Pretty simple! You can override any of the other settings this way too, like the proxy settings (there's an example in the default settings.php file), headers , and whether to verify certificates for https requests.