Add modbus plugin

This commit implements a modbus plugin.
It installs required packages and generates configuration for hosts and
datasets.

README.md

@@ -153,6 +153,7 @@ documentation for each plugin for configurable attributes.
 * `memcached`(see [collectd::plugin::memcached](#class-collectdpluginmemcached)
   below )
 * `memory`(see [collectd::plugin::memory](#class-collectdpluginmemory) below )
+* `modbus` (see [collectd::plugin::modbus](#class-collectdpluginmodbus) below)
 * `mongodb`(see [collectd::plugin::mongodb](#class-collectdpluginmongodb) below )
 * `mysql` (see [collectd::plugin::mysql](#class-collectdpluginmysql) below)
 * `netlink` (see [collectd::plugin::netlink](#class-collectdpluginnetlink) below)
@@ -1073,6 +1074,35 @@ class { 'collectd::plugin::memory':
 }
 ```
 
+#### Class: `collectd::plugin::modbus`
+
+```puppet
+class {'collectd::plugin::modbus':
+  ensure => 'present',
+  data   =>  {
+    current_phase_a => {
+      'type'          => 'gauge',
+      'instance'      => 'current phase A',
+      'register_base' => 1234,
+      'register_type' => 'Float',
+    }
+  },
+  hosts  => {
+    meter123 => {
+      'address'   => '127.0.0.1',
+      'port'      => '502',
+      'interval'  => 10,
+      'slaves'    => {
+        255 => {
+          'instance' => 'power meter 255',
+          'collect'  => ['current_phase_a'],
+        }
+      },
+    }
+  },
+}
+```
+
 #### Class: `collectd::plugin::mysql`
 
 ```puppet

manifests/plugin/modbus.pp

@@ -0,0 +1,72 @@
+# @summary Creates configuration for a collectd modbus plugin
+#
+# More information on the modbus plugin configuration options:
+# https://collectd.org/wiki/index.php/Plugin:Modbus
+#
+# @example
+#
+# class {'collectd::plugin::modbus':
+#   ensure => 'present',
+#   data   =>  {
+#     current_phase_a => {
+#       'type'          => 'gauge',
+#       'instance'      => 'current phase A',
+#       'register_base' => 1234,
+#       'register_type' => 'Float',
+#     }
+#   },
+#   hosts  => {
+#     meter123 => {
+#       'address'   => '127.0.0.1',
+#       'port'      => '502',
+#       'interval'  => 10,
+#       'slaves'    => {
+#         255 => {
+#           'instance' => 'power meter 255',
+#           'collect'  => ['current_phase_a'],
+#         }
+#       },
+#     }
+#   },
+# }
+#
+# @param ensure
+#   Ensures modbus module
+# @param manage_package
+#   If enabled, install required packages
+# @param data
+#   Defines data set configuration
+# @param hosts
+#   Defines hosts configuration
+
+class collectd::plugin::modbus (
+  Enum['present', 'absent']               $ensure         = 'present',
+  Optional[Boolean]                       $manage_package = undef,
+  Hash[String[1], Collectd::Modbus::Data] $data           = {},
+  Hash[String[1], Collectd::Modbus::Host] $hosts          = {},
+) {
+  include collectd
+
+  $_manage_package = pick($manage_package, $collectd::manage_package)
+
+  if $facts['os']['family'] == 'RedHat' {
+    if $_manage_package {
+      package { 'collectd-modbus':
+        ensure => $ensure,
+      }
+    }
+  }
+
+  if $facts['os']['family'] == 'Debian' {
+    if $_manage_package {
+      package { 'libmodbus5':
+        ensure => $ensure,
+      }
+    }
+  }
+
+  collectd::plugin { 'modbus':
+    ensure   => $ensure,
+    content  => template('collectd/plugin/modbus.conf.erb'),
+  }
+}

spec/classes/collectd_plugin_modbus_spec.rb

@@ -0,0 +1,88 @@
+require 'spec_helper'
+
+describe 'collectd::plugin::modbus', type: :class do
+  on_supported_os(baseline_os_hash).each do |os, facts|
+    context "on #{os} " do
+      let :facts do
+        facts
+      end
+      let :pre_condition do
+        'include collectd'
+      end
+
+      options = os_specific_options(facts)
+
+      context ':ensure => present and dataset for Current Phase A' do
+        let :params do
+          {
+            data: {
+              'current_phase_a' => {
+                'type'          => 'gauge',
+                'instance'      => 'Current Phase A',
+                'register_base' => 1234,
+                'register_type' => 'Float',
+              }
+            },
+            hosts: {
+              'power123' => {
+                'address'  => '127.0.0.1',
+                'port'     => '502',
+                'interval' => 10,
+                'slaves'   => {
+                  255 => {
+                    'instance' => 'power meter 255',
+                    'collect'  => ['current_phase_a'],
+                  }
+                }
+              }
+            }
+          }
+        end
+
+        it "Will create #{options[:plugin_conf_dir]}/10-modbus.conf" do
+          is_expected.to contain_file('modbus.load').with(
+            ensure: 'present',
+            path: "#{options[:plugin_conf_dir]}/10-modbus.conf",
+            content: %r{Data "current_phase_a".+Instance "Current Phase A".+Host "power123".+Slave 255}m
+          )
+        end
+      end
+
+      context ':ensure => absent' do
+        let :params do
+          {
+            ensure: 'absent',
+            data: {
+              'current_phase_a' => {
+                'type'          => 'gauge',
+                'instance'      => 'Current Phase A',
+                'register_base' => 1234,
+                'register_type' => 'Float',
+              }
+            },
+            hosts: {
+              'power123' => {
+                'address'  => '127.0.0.1',
+                'port'     => '502',
+                'interval' => 10,
+                'slaves'   => {
+                  255 => {
+                    'instance' => 'power meter 255',
+                    'collect'  => ['current_phase_a'],
+                  }
+                }
+              }
+            }
+          }
+        end
+
+        it "Will not create #{options[:plugin_conf_dir]}/10-modbus.conf" do
+          is_expected.to contain_file('modbus.load').with(
+            ensure: 'absent',
+            path: "#{options[:plugin_conf_dir]}/10-modbus.conf"
+          )
+        end
+      end
+    end
+  end
+end

templates/plugin/modbus.conf.erb

@@ -0,0 +1,40 @@
+<% if @data or @hosts -%>
+<Plugin modbus>
+<% @data.sort_by {|k,v| k}.each do |key,val| -%>
+  <Data "<%= key %>">
+    Type "<%= val['type'] %>"
+<% if val['instance'] -%>
+    Instance "<%= val['instance'] %>"
+<% end -%>
+<% if val['register_base'] -%>
+    RegisterBase <%= val['register_base'] %>
+<% end -%>
+<% if val['register_type'] -%>
+    RegisterType <%= val['register_type'] %>
+<% end -%>
+  </Data>
+<% end -%>
+
+<% @hosts.sort_by {|k,v| k}.each do |key,val| -%>
+  <Host "<%= key %>">
+    Address "<%= val['address'] %>"
+<%   if val['port'] -%>
+    Port <%= val['port'] %>
+<%   end -%>
+<%   if val['interval'] -%>
+    Interval <%= val['interval'] %>
+<%   end -%>
+<% if val['slaves'] -%>
+<%   Array(val['slaves']).sort_by {|k,v| k}.each do |slave_key,slave_val| -%>
+    <Slave <%= slave_key %>>
+<%     if slave_val['instance'] -%>
+      Instance "<%= slave_val['instance'] %>"
+<%     end -%>
+      Collect <%= Array(slave_val['collect']).sort.map { |x| %("#{x}") }.join(' ') %>
+    </Slave>
+<%   end -%>
+<% end -%>
+  </Host>
+<% end -%>
+</Plugin>
+<% end -%>

types/modbus/data.pp

@@ -0,0 +1,2 @@
+#
+type Collectd::Modbus::Data = Struct[{Optional['instance'] => String, NotUndef['type'] => String[1], NotUndef['register_base'] => Numeric, NotUndef['register_type'] => String[1]}]

types/modbus/host.pp

@@ -0,0 +1,2 @@
+#
+type Collectd::Modbus::Host = Struct[{NotUndef['address'] => String[1], NotUndef['port'] => String[1], NotUndef['slaves'] => Hash[Integer, Collectd::Modbus::Slave], Optional['interval'] => Integer[0]}]

types/modbus/slave.pp

@@ -0,0 +1,2 @@
+#
+type Collectd::Modbus::Slave = Struct[{NotUndef['instance'] => String[1], NotUndef['collect'] => Variant[String[1], Array[String[1], 1]]}]