Export workflow into docker

Hello everyone,
I’m trying to export my workflows into docker. I have limited experience with docker. I followed instructions to create a (base-)image of knime.
Know I would like to export a simple workflow as image to run it in docker. According to
https://www.knime.com/denbicibi-contributions this should be done by file->containerization->export workflow as docker image. I get a window to select a workflow, then “image name and tag” and “update sites” etc.
At the end (finish button) I get the following error:
“KNIME project could not be exported. Reason: Export of workflows did not succeed: Java.lang.ClassNotFoundException: org.erlwood.knime.utils.auth.ntlm.DefaultTrustClientBuilder cannot be found by de.nbi.cibi.docker_1.0.0.201806221309”

Please any suggestion to fix it. Does it require some trust certifications?
Thank you.

does your workflow contain erlwood nodes? Maybe you have not entered the update site for those nodes in the export wizard?
Kind regards

Hi @AlexanderFillbrunn,
thank you for your response. No I don’t use any erlwood nodes. To try I created a workflow that contains one node (Table Creator). I get the same issue.
I think it is something wrong in the setting … Under preferences->Erlwood->Authentication preferences there are Workflow Credentials Name etc. do I have to edit them?
I uninstall the extension of erlwood…
Best regards

Hi @ls_ahl ,
does it work without the Erlwood-Extension installed?
Kind regards

Hi @AlexanderFillbrunn,
I cant’ say … I get another error message: org.apache.cxf.jaxrs.clientBuilderImpl cannot be found by de.nbi.cibi.docker_…
Best regards

Hi @ls_ahl,
well, that should not happen at all. I will have a look and notify you when it is fixed.
Kind regards

Hi @ls_ahl,
could you send me your KNIME log? You find it under View --> Open KNIME Log. You can also send it via private message, if you want. You don’t have to post it here. The libraries it does not find should not even be used by the Docker exporter, especially not the Erl wood extension. Having a look at the log would help me figure out what is going on here.
Kind regards

the issue was caused by a permission conflict. The error messages I got were untraceable.
First, check whether you can run:

docker ps
using your current user, If not, then you could have the same problem as mine.

Got permission denied while trying to connect to the Dokcer deamon socket at …

Short and easy answer:

sudo chmod 666 /var/run/docker.sock
Now you should be able as non root to run: docker ps and knime can connect docker

After reinstalling everything (knime, docker …), I found that the user-account I use to run knime doesn’t have the permissions to connect the docker instance. I got this message after the reinstall.
check first which groups exist and where is docker group located with


Then add your current user to the group of docker.

sudo usermod -aG dokcer $USER

Note: This didn’t work for me, because docker group is located under root … that’s why I changed the access permissions of docker.sock to be accessible by any user…

After that knime should be able to connect docker instance and create an image of the workflow.
Thanks @AlexanderFillbrunn


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