Enabling and configuring watch folder using the installation toolkit

You can use the installation toolkit to enable and configure the watch folder function in the cluster definition file. The watch folder packages (gpfs.kafka and gpfs.librdkafka) are installed on all supported nodes in the cluster specified to the installation toolkit during the installation, even if watch folder is not enabled in the cluster configuration. Based on the watch folder configuration options specified in the cluster definition file using the installation toolkit, the function is enabled and configured in the cluster accordingly during the deployment. For information about prerequisites for gpfs.kafka and gpfs.librdkafka packages, see Requirements for watch folder.

Considerations for the watch folder function include:

If you have at least 3 protocol nodes defined, you can choose to have those used as broker nodes for the message queue. Otherwise, you need to specify at least 3 nodes that have the gpfs.kafka and gpfs.librdkafka packages installed on them to act as broker nodes for the message queue. Use the following command to specify a node as a broker node.
```
./spectrumscale node add NodeName -b
```
If watch folder is enabled, message queue is also enabled. However, individual watches need to be set up manually by using the mmwatch command.

You can configure the watch folder related options in the cluster definition file by using the installation toolkit as follows.

By default, watch folder is disabled in the cluster definition file.

To enable watch folder in the cluster definition file, issue the following command before performing deployment with the installation toolkit:

./spectrumscale watchfolder enable

A sample output is as follows:

[ INFO ] Enabling watch folder in the cluster configuration file.
[ INFO ] The watch folder feature provides a new method of monitoring and performing actions on  
[ INFO ] file system events in IBM Spectrum Scale. To complete the watch folder configuration please 
[ INFO ] contact your IBM Client Technical Specialist (or send an email to scale@us.ibm.com) 
[ INFO ] to review your use case and receive instructions to enable the feature in your environment.
[ INFO ] if you do not want to enable watch folder, you can run: ./spectrumscale watchfolder disable .
[ INFO ] Tip :If watch folder is enabled for the cluster, the message queue will be enabled.
[ INFO ] If you have at least 3 protocol nodes defined, you do not need to use the '-b' flag to designate 
[ INFO ] a node as a broker node. Otherwise, you need to specify at least 3 nodes to have the Kafka packages  
[ INFO ] installed on and act as broker nodes for the message queue. Use the following command to designate 
[ INFO ] a node as a broker node: ./spectrumscale node add node_name -b .

To disable watch folder in the cluster definition file, issue the following command:
```
./spectrumscale watchfolder disable
```
To list the watch folder configuration in the cluster definition file, issue the following command:
```
./spectrumscale watchfolder list
```

Note: These watch folder configuration-related changes become effective after the deployment procedure, initiated with ./spectrumscale deploy, is completed.