Add fact to get grafana version

lib/facter/grafana_version.rb

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

spec/facter/grafana_version_spec.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+require 'facter'
+
+describe 'grafana_version' do
+  before do
+    Facter.clear
+  end
+
+  context 'when VERSION file exists' do
+    it 'returns the version from the VERSION file' do
+      version = '1.2.3'
+      version_path = '/usr/share/grafana/VERSION'
+
+      allow(File).to receive(:exist?).with(version_path).and_return(true)
+      allow(File).to receive(:read).with(version_path).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