symfony + knp_snappy : gtk-WARNING 无法打开显示

symfony + knp_snappy : gtk-WARNING cannot open display

在 symfony 应用程序中,我使用 knp_snappy 生成 PDF :

return new Response(
         $this->get('knp_snappy.pdf')->getOutput($url),
         200,
         array(
                 'Content-Type'          => 'application/pdf',
                'Content-Disposition'   => 'attachment; filename="file.pdf"'
                )
        );

但我收到此错误:

The exit status code '1' says something went wrong:
stderr: "Loading pages (1/6)java version "1.7.0_79"

[more here ... cut for clarity]

OpenJDK Runtime Environment (IcedTea 2.5.6) (7u79-2.5.6-0ubuntu1.14.04.1)
OpenJDK 64-Bit Server VM (build 24.79-b02, mixed mode)

(wkhtmltopdf:12934): Gtk-WARNING **: cannot open display:
"
stdout: ""
command: wkhtmltopdf --lowquality 'http://symfony.dev/app_dev.php/application/reporter/674/inventory' '/tmp/knp_snappy5643248854b563.21161953.pdf'. 

请注意:

重点是所请求的 URL 在防火墙后面,因此 wkhtmltopdf 收到 302 访问被拒绝。

knp_snappy 遇到同样问题的用户,解决方案解释得很好here and here

希望对您有所帮助!