Add fact to get grafana version

lib/facter/grafana_version.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+Facter.add(:grafana_version) do
+  confine { Facter::Util::Resolution.which('grafana-server') }
+
+  setcode do
+    version_path = '/usr/share/grafana/VERSION'
+    File.read(version_path).strip if File.exist?(version_path)
+  end
+end

spec/facter/grafana_version_spec.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require 'facter'
+
+describe 'grafana_version' do
+  before do
+    Facter.clear
+    allow(Facter::Util::Resolution).to receive(:which).with('grafana-server').and_return('/usr/sbin/grafana-server')
+  end
+
+  context 'when VERSION file exists' do
+    it 'returns the version from the VERSION file' do
+      version = '1.2.3'
+      allow(File).to receive(:exist?).with('/usr/share/grafana/VERSION').and_return(true)
+      allow(File).to receive(:read).with('/usr/share/grafana/VERSION').and_return(version)
+
+      expect(Facter.fact(:grafana_version).value).to eq(version.strip)
+    end
+  end
+
+  context 'when VERSION file does not exist' do
+    it 'returns nil' do
+      allow(File).to receive(:exist?).with('/usr/share/grafana/VERSION').and_return(false)
+
+      expect(Facter.fact(:grafana_version).value).to be_nil
+    end
+  end
+end