Install a logstash-plugin from a local gem repository

Elastic Stack Logstash
1

I have a local gem repository which is configured on my host's gem sources.
When I run the logstash plugin command to install a plugin, it says that it failed to connect to rubygems.org (which is OK).
Is there a way to tell logstash-plugin to take my local gem repo address into consideration when looking for this gem?

Thanks,

2

Adding that unpacking the gem and editing the Gemfile is not possible for me since the repository URL changes between environments.

Thanks,