I have in my kibana directory a custom plugin "custom_plugin" My impression from reading this portion of the elastic docs is that the directory needs to be zipped.
So based on that, I do:
zip -r custom_plugin.zip custom_plugin
Then, adhering to the elastic doc example, I run:
mkdir plugins bin/kibana-plugin install file:///custom_plugin.zip -d plugins
I get the following output:
Warning: Using the -d, --plugin-dir option is deprecated, and is known to not work for all plugins, including X-Pack.
Attempting to transfer from file:///custom_plugin.zip Error: ENOTFOUND
Plugin installation was unsuccessful due to error "No valid url specified."