@@ -12,9 +12,30 @@ use Composer\Repository\CompositeRepository;
 use Composer\Repository\RepositoryInterface;
 use SilverStripe\Core\Environment;
 use SilverStripe\Core\Extension;
+use SilverStripe\Core\Config\Config;
 
 class ComposerLoaderExtension extends Extension
 {
+    /**
+     * For http repositories:
+     * Fully qualified domain names from which any repositories should not be checked.
+     *
+     * For ssh repositories:
+     * The portion of the ssh URI after @ but before :
+     *
+     * @example
+     * for https://github.com/some-account/some-repository.git:
+     * github.com
+     *
+     * @example
+     * for git@git.cwp.govt.nz:some-stack/some-repository.git:
+     * git.cwp.govt.nz
+     *
+     * @config
+     * @var array
+     */
+    private static $ignored_repository_hosts = [];
+
     /**
      * @var Composer
      */
@@ -57,6 +78,23 @@ class ComposerLoaderExtension extends Extension
                 continue;
             }
 
+            // Filter out packages from hosts which should be ignored
+            $ignoredHosts = (array) Config::inst()->get(self::class, 'ignored_repository_hosts');
+            $sourceURL = $package->getSourceUrl();
+            if ($host = parse_url($sourceURL, PHP_URL_HOST)) {
+                if (in_array($host, $ignoredHosts)) {
+                    continue;
+                }
+            } else {
+                // Some ssh URIs aren't parsed correctly by parse_url
+                foreach ($ignoredHosts as $host) {
+                    if (preg_match('/^.+?@' . $host . ':/', $sourceURL)) {
+                        // continue outer loop
+                        continue 2;
+                    }
+                }
+            }
+
             // Find the constraint used for installation
             $constraint = $this->getInstalledConstraint($repository, $package->getName());
             $packages[$package->getName()] = [