Line Reader: Direct access to the local file system is not allowed on KNIME Server.

KNIME Server
1

Hej,

After the recent update to 4.10.1, I have some issues with the Line Reader:
I have workflows in which I download and/or create files into temporary folders and like to read them back from there. The creation is performed by an external tool.
But when I try to read the file using the Line Reader, I get the above mentioned Error and the workflow finishes with an error.

Is this intentional, and if yes, is there a way to read the files at least in some folders, like in a temporary folder created inside the workflow folder?

Best,
Julian

2

Hi,
If you select the option to create the temporary folder in the workflow directory and then use the flow variable for the download and for reading the file, it should work. The message is intentional, as, apart from general security, with distributed executors the local file system is not what you might expect (ie the server file system).
Kind regards
Alexander

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3

Hej Alexander,

Thanks for the information, I guess I figured it out now. So, the temporary file has to be in the temporarily created folder AND it must also have a name specified by the node which creates the folder. At least, with this and the “knime://…” as file path in the “Line Reader” it does work.

Thanks,
Julian

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4

Hi @julianu and @AlexanderFillbrunn,
Please would you mind sharing an image or workflow of how to set this up? I have the same problem reading Excel files from a shared drive. This worked fine with Server 4.10.0 and stopped working with the update to 4.10.1.
Thanks!

6

Hej @supersharp,
I know it did work reading from a shared drive (or anywhere on the file system), but with the solution discussed here it only works in a folder created by the “Create Temp Dir”. You can create a variable in this node and copy the file to the folder by any means. If the file is in place, the Line Reader works fine.

I will most probably also need to read files from share-mounts… did not try this after the update though.

7

Hi @supersharp,
with the new Excel Reader reading the local file system on the server does not work anymore, as the distributed executors feature allows the workflow to be executed on a completely different system, where the shared drive might not even be mounted. But if you can access the shared drive via FTP or SFTP, you can use the FTP Connection or SSH Connection in combination with a File Download node and a Create Temp Dir as described above.
Kind regards
Alexander