allow managing /etc/alloy/config.alloy

Author: evgeni

.fixtures.yml

@@ -2,4 +2,5 @@
 fixtures:
   repositories:
     apt: 'https://github.com/puppetlabs/puppetlabs-apt'
+    stdlib: 'https://github.com/puppetlabs/puppetlabs-stdlib'
     yumrepo_core: 'https://github.com/puppetlabs/puppetlabs-yumrepo_core'

manifests/init.pp

@@ -1,10 +1,27 @@
 # @summary Install and configure Grafana Alloy
+#
+# @param config
+#   The contents of the configuration file, if any
 class grafana_alloy (
+  Optional[String[1]] $config = undef,
 ) {
   require grafana_alloy::repo
   package { 'alloy': }
-  -> service { 'alloy':
-    ensure => 'running',
-    enable => true,
+
+  if $config {
+    file { '/etc/alloy/config.alloy':
+      content => $config,
+      mode    => '0640',
+      owner   => 'root',
+      group   => 'alloy',
+      require => Package['alloy'],
+      notify  => Service['alloy'],
+    }
+  }
+
+  service { 'alloy':
+    ensure  => 'running',
+    enable  => true,
+    require => Package['alloy'],
   }
 }

spec/acceptance/init_spec.rb

@@ -12,4 +12,30 @@
       end
     end
   end
+
+  describe 'with config' do
+    it_behaves_like 'an idempotent resource' do
+      let(:config) do
+        <<-CONFIG
+          prometheus.exporter.unix "default" {
+            include_exporter_metrics = true
+          }
+
+          prometheus.scrape "default" {
+            targets = concat(
+              prometheus.exporter.unix.default.targets,
+            )
+            forward_to = []
+          }
+        CONFIG
+      end
+      let(:manifest) do
+        <<-PUPPET
+        class { 'grafana_alloy':
+          config => '#{config}'
+        }
+        PUPPET
+      end
+    end
+  end
 end

spec/classes/grafana_alloy_spec.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'grafana_alloy' do
+  on_supported_os.each do |os, os_facts|
+    context "on #{os}" do
+      let(:facts) { os_facts }
+      let(:params) { {} }
+
+      context 'with default params' do
+        it { is_expected.to compile.with_all_deps }
+        it { is_expected.not_to contain_file('/etc/alloy/config.alloy') }
+      end
+
+      context 'with all params' do
+        let(:params) { super().merge(config: 'my config') }
+
+        it { is_expected.to compile.with_all_deps }
+        it { is_expected.to contain_file('/etc/alloy/config.alloy').with_content('my config') }
+      end
+    end
+  end
+end