Installation

JiraMetrics should run on any Ruby runtime that supports version 3.0 or higher. Instructions below are for CRuby, which is also known as MRI, and for JRuby, which runs on the Java Virtual Machine (JVM).

Unless you have a reason to want to run on the JVM, I’d recommend using CRuby.

CRuby (formerly called MRI Ruby)

If you’re on a mac, you may have noticed that Ruby is already installed on your machine. The bad news is that it’s likely too old to be useful. Run ruby -v and if the version is less than 3.0 then you’ll still need to install a newer version.

Install CRuby itself with the instructions here. If you’re using Windows, there is a one-click installer. If you’re on almost any other platform, your local package manager will have a way to do that. In my case, I’m using a mac so it’s as simple as brew install ruby
Once Ruby is installed, you can install JiraMetrics with this command.
```
gem install jirametrics
```
You can then invoke jirametrics directly from the terminal.
Optional: If you want to use the dependency report then you’ll want to install graphviz

JRuby

Install JRuby 9.4 or higher. In my case that’s as simple as brew install jruby. If you aren’t using brew then see the JRuby download instructions.
Set the JAVA_OPTS environment variable as shown here. If you don’t do that then the tool will hang when it tries to generate the dependency report.
```
export JAVA_OPTS="--add-opens java.base/sun.nio.ch=ALL-UNNAMED --add-opens java.base/java.io=ALL-UNNAMED"
```
Install jirametrics with…
```
jruby -S gem install jirametrics
```
You will now invoke the tool with jruby -S jirametrics instead of just jirametrics as the rest of the instructions say. Everything else is the same.
Optional: If you want to use the dependency report then you’ll want to install graphviz