# 2. Modify Cluster Configuration¶

If you haven’t already done so, you will need to first have a corresponding cluster configuration file for the cluster you intend to submit Interactive Apps (Plugins) batch jobs to. It is recommended you follow the directions on Add Cluster Configuration Files.

Modify the cluster configuration file with the necessary information so that a batch script generated from an interactive app can find the installed copies of TurboVNC and websockify:

# /etc/ood/config/clusters.d/my_cluster.yml
---
v2:
title: "Cluster 1"
host: "my_cluster.my_center.edu"
job:
...
batch_connect:
basic:
script_wrapper: |
module purge
%s
vnc:
script_wrapper: |
module purge
export PATH="/usr/local/turbovnc/bin:$PATH" export WEBSOCKIFY_CMD="/usr/local/websockify/run" %s  where we introduced the configuration option batch_connect that allows us to add global settings for both a basic interactive web server as well as a vnc interactive web server. In the above case we modify the global setting script_wrapper for both basic and vnc sessions. This allows us to supply bash code that wraps around the body of the template script (specified by %s). First, we purge the module environment to remove any conflicting modules that may have been loaded by the user’s .bashrc or .bash_profile files. Then we specify the required environment needed by the vnc script to launch TurboVNC and websockify. Note You will most likely need to replace the block of code below in your cluster configuration file: script_wrapper: | module purge export PATH="/usr/local/turbovnc/bin:$PATH"
export WEBSOCKIFY_CMD="/usr/local/websockify/run"
%s


with a block that adds the full path to the TurboVNC binaries into the PATH environment variable as well as the corresponding websockify launcher into the WEBSOCKIFY_CMD environment variable.

Warning

Do not forget to include the %s in the script_wrapper configuration option. Otherwise the actual bash code that launches the corresponding web servers will never be interpolated into the main batch script and run.