Fresh install - Error: (0) file_get_contents(): Filename cannot be empty

[mj84]

Hello,

I'm in the middle of building a NagVis container image which I'd like to run in Kubernetes.
I am following the "manual installation" approach as documented in http://docs.nagvis.org/1.9/en_US/installation_instructions.html

My image is based on bullseye-slim and I'm running Apache 2.4 with mod_php7.4.
I have completed every step from the manual instructions, except 7 and 8.

When I try to access NagVis via curl -vv http://172.17.0.2:8080/nagvis/frontend/nagvis-js/index.php , I receive a HTTP/1.1 200 OK, but the following error message is printed:

Error: (0) file_get_contents(): Filename cannot be empty<div class="details">URL: /nagvis/frontend/nagvis-js/index.php?mod=Info<br>
File: /usr/local/nagvis/share/frontend/nagvis-js/ext/dwoo-1.1.0/Dwoo/Template/File.php<br>
Line: 120<br>
<code>#0 [internal function]: nagvisExceptionErrorHandler()<br>
#1 /usr/local/nagvis/share/frontend/nagvis-js/ext/dwoo-1.1.0/Dwoo/Template/File.php(120): file_get_contents()<br>
#2 /usr/local/nagvis/share/frontend/nagvis-js/ext/dwoo-1.1.0/Dwoo/Compiler.php(649): Dwoo_Template_File->getSource()<br>
#3 /usr/local/nagvis/share/frontend/nagvis-js/ext/dwoo-1.1.0/Dwoo/Template/String.php(369): Dwoo_Compiler->compile()<br>
#4 /usr/local/nagvis/share/frontend/nagvis-js/ext/dwoo-1.1.0/Dwoo.php(363): Dwoo_Template_String->getCompiledTemplate()<br>
#5 /usr/local/nagvis/share/frontend/nagvis-js/classes/NagVisLoginView.php(76): Dwoo->get()<br>
#6 /usr/local/nagvis/share/frontend/nagvis-js/classes/FrontendModLogonDialog.php(48): NagVisLoginView->parse()<br>
#7 /usr/local/nagvis/share/server/core/functions/index.php(120): FrontendModLogonDialog->handleAction()<br>
#8 /usr/local/nagvis/share/frontend/nagvis-js/index.php(53): require('/usr/local/nagv...')<br>

Unfortunately, the Apache2 error log stays empty.
How can I find the cause for this error?

I understand, that NagVis is trying to write a template using Dwoo, but it complains about a missing / empty filename.

Am I missing some configuration in nagvis.ini.php?
I simply copied the nagvis.ini.php-sample to nagvis.ini.php.

Any hints would be appreciated!