Add nova::compute::libvirt::qemu class to configure limits

This change adds a class meant to configure the max_files and
max_processes limits in libvirt/qemu.conf, it uses augeas and supports
config cleanup.

Change-Id: I5fa423a4b212d14f6e9ff6a270931b569558b54e

manifests/compute/libvirt/qemu.pp

@@ -0,0 +1,55 @@
+# == Class: nova::compute::libvirt::qemu
+#
+# Configures qemu limits for use by libvirt
+#
+# === Parameters:
+#
+# [*configure_qemu*]
+#   (optional) Whether or not configure qemu bits.
+#   Defaults to false.
+#
+# [*max_files*]
+#   (optional) Maximum number of opened files, per process.
+#   Defaults to 1024.
+#
+# [*max_processes*]
+#   (optional) Maximum number of processes that can be run by qemu user.
+#   Defaults to 4096.
+#
+class nova::compute::libvirt::qemu(
+  $configure_qemu = false,
+  $max_files      = 1024,
+  $max_processes  = 4096,
+){
+
+  include ::nova::deps
+  require ::nova::compute::libvirt
+
+  Anchor['nova::config::begin']
+  -> Augeas<| tag == 'qemu-conf-augeas'|>
+  -> Anchor['nova::config::end']
+
+  Augeas<| tag == 'qemu-conf-augeas'|>
+  ~> Service['libvirt']
+
+  if $configure_qemu {
+
+    augeas { 'qemu-conf-limits':
+      context => '/files/etc/libvirt/qemu.conf',
+      changes => [
+        "set max_files ${max_files}",
+        "set max_processes ${max_processes}",
+      ],
+      tag     => 'qemu-conf-augeas',
+    }
+  } else {
+    augeas { 'qemu-conf-limits':
+      context => '/files/etc/libvirt/qemu.conf',
+      changes => [
+        'rm max_files',
+        'rm max_processes',
+      ],
+      tag     => 'qemu-conf-augeas',
+    }
+  }
+}

releasenotes/notes/libvirt-qemu-limits-efb8668de1de48e8.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - A new nova::compute::libvirt::qemu class has been added
+    with the initial purpose of configuring the max_files
+    and max_processes limits in qemu.conf

spec/classes/nova_compute_libvirt_qemu_spec.rb

@@ -0,0 +1,66 @@
+require 'spec_helper'
+
+describe 'nova::compute::libvirt::qemu' do
+
+  let :pre_condition do
+   'include nova
+    include nova::compute
+    include nova::compute::libvirt'
+  end
+
+  shared_examples_for 'nova compute libvirt with qemu' do
+
+    context 'when not configuring qemu' do
+      let :params do
+        {
+          :configure_qemu => false
+        }
+      end
+      it { is_expected.to contain_augeas('qemu-conf-limits').with({
+        :context => '/files/etc/libvirt/qemu.conf',
+        :changes => [ "rm max_files", "rm max_processes" ],
+      }).that_notifies('Service[libvirt]') }
+    end
+
+    context 'when configuring qemu by default' do
+      let :params do
+        {
+          :configure_qemu => true
+        }
+      end
+      it { is_expected.to contain_augeas('qemu-conf-limits').with({
+        :context => '/files/etc/libvirt/qemu.conf',
+        :changes => [ "set max_files 1024", "set max_processes 4096" ],
+        :tag     => 'qemu-conf-augeas',
+      }).that_notifies('Service[libvirt]') }
+    end
+
+    context 'when configuring qemu with overriden parameters' do
+      let :params do
+        {
+          :configure_qemu => true,
+          :max_files => 32768,
+          :max_processes => 131072,
+        }
+      end
+      it { is_expected.to contain_augeas('qemu-conf-limits').with({
+        :context => '/files/etc/libvirt/qemu.conf',
+        :changes => [ "set max_files 32768", "set max_processes 131072" ],
+        :tag     => 'qemu-conf-augeas',
+      }).that_notifies('Service[libvirt]') }
+    end
+  end
+
+  on_supported_os({
+     :supported_os => OSDefaults.get_supported_os
+   }).each do |os,facts|
+     context "on #{os}" do
+       let (:facts) do
+         facts.merge!(OSDefaults.get_facts())
+       end
+
+      it_configures 'nova compute libvirt with qemu'
+     end
+  end
+
+end