Acquia\Cloud\Api\CloudApiClient::copyDatabase PHP Method

    public function copyDatabase($site, $db, $sourceEnv, $targetEnv)
    {
        $variables = array('site' => $site, 'db' => $db, 'source' => $sourceEnv, 'target' => $targetEnv);
        $request = $this->post(array('{+base_path}/sites/{site}/dbs/{db}/db-copy/{source}/{target}.json', $variables));
        return new Response\Task($request);
    }