Support generic postgres custom metrics

manifests/integrations/mysql.pp

@@ -3,10 +3,10 @@
 # This class will install the necessary configuration for the mysql integration
 #
 # Parameters:
-#   $host:
-#       The host mysql is running on
 #   $password
 #       The mysql password for the datadog user
+#   $host:
+#       The host mysql is running on
 #   $user
 #       The mysql user for the datadog user
 #   $sock
@@ -37,8 +37,8 @@
 #
 #
 class datadog_agent::integrations::mysql(
-  $host = 'localhost',
   $password,
+  $host = 'localhost',
   $user = 'datadog',
   $sock = undef,
   $tags = [],

manifests/integrations/pgbouncer.pp

@@ -3,14 +3,14 @@
 # This class will install the necessary configuration for the pgbouncer integration
 #
 # Parameters:
+#   $password
+#       The password for the datadog user
 #   $host:
 #       The host pgbouncer is listening on
 #   $port
 #       The pgbouncer port number
 #   $username
 #       The username for the datadog user
-#   $password
-#       The password for the datadog user
 #   $tags
 #       Optional array of tags
 #
@@ -25,10 +25,10 @@
 #
 #
 class datadog_agent::integrations::pgbouncer(
+  $password,
   $host   = 'localhost',
   $port   = '6432',
   $username = 'datadog',
-  $password,
   $tags = [],
 ) inherits datadog_agent::params {
 

manifests/integrations/postgres.pp

@@ -3,6 +3,8 @@
 # This class will install the necessary configuration for the postgres integration
 #
 # Parameters:
+#   $password
+#       The password for the datadog user
 #   $host:
 #       The host postgres is running on
 #   $dbname
@@ -11,14 +13,18 @@
 #       The postgres port number
 #   $username
 #       The username for the datadog user
-#   $password
-#       The password for the datadog user
 #   $tags
 #       Optional array of tags
 #   $tables
 #       Track per relation/table metrics. Array of strings.
 #       Warning: this can collect lots of metrics per relation
 #       (10 + 10 per index)
+#   $tags
+#       Optional array of tags
+#   $custom_metrics
+#       A hash of custom metrics with the following keys - query, metrics,
+#       relation, descriptors. Refer to this guide for details on those fields:
+#       https://help.datadoghq.com/hc/en-us/articles/208385813-Postgres-custom-metric-collection-explained
 #
 # Sample Usage:
 #
@@ -27,17 +33,30 @@
 #    dbname   => 'postgres'
 #    username => 'datadog',
 #    password => 'some_pass',
+#    custom_metrics => {
+#      a_custom_query => {
+#        query => "select tag_column, %s from table",
+#        relation => false,
+#        metrics => {
+#          value_column => ["value_column.datadog.tag", "GAUGE"]
+#        },
+#        descriptors => [
+#          ["tag_column", "tag_column.datadog.tag"]
+#        ]
+#      }
+#    }
 #  }
 #
 #
 class datadog_agent::integrations::postgres(
+  $password,
   $host   = 'localhost',
   $dbname = 'postgres',
   $port   = '5432',
   $username = 'datadog',
-  $password,
   $tags = [],
-  $tables = []
+  $tables = [],
+  $custom_metrics = {},
 ) inherits datadog_agent::params {
   include datadog_agent
 
@@ -53,4 +72,6 @@
     require => Package[$datadog_agent::params::package_name],
     notify  => Service[$datadog_agent::params::service_name],
   }
+
+  create_resources('datadog_agent::integrations::postgres_custom_metric', $custom_metrics)
 }

manifests/integrations/postgres_custom_metric.pp

@@ -0,0 +1,27 @@
+##
+# The postgres_custom_metric defines a custom sql metric.
+# https://help.datadoghq.com/hc/en-us/articles/208385813-Postgres-custom-metric-collection-explained
+#
+# $query:
+#   The custom metric SQL query. It must contain a '%s' for defining the metrics.
+#
+# $metrics:
+#   a hash of column name to metric definition. a metric definition is an array
+#   consisting of two columns -- the datadog metric name and the metric type.
+#
+# $relation:
+#   ?
+#
+# $descriptor:
+#   an array that maps an sql column's to a tag. Each descriptor consists of two
+#   fields -- column name, and datadog tag.
+define datadog_agent::integrations::postgres_custom_metric(
+  $query,
+  $metrics,
+  $relation = false,
+  $descriptors = [],
+) {
+  validate_re($query, '^.*%s.*$', 'custom_metrics require %s for metric substitution')
+  validate_hash($metrics)
+  validate_array($descriptors)
+}

spec/classes/datadog_agent_integrations_postgres_spec.rb

@@ -55,6 +55,53 @@
       it { should contain_file(conf_file).with_content(%r{username: monitoring}) }
       it { should contain_file(conf_file).with_content(%r{^[^#]*tags:\s+- foo\s+- bar\s+- baz}) }
       it { should contain_file(conf_file).with_content(%r{^[^#]*relations:\s+- furry\s+- fuzzy\s+- funky}) }
+
+      context 'with custom metric query missing %s' do
+        let(:params) {{
+          host: 'postgres1',
+          dbname: 'cats',
+          port: 4142,
+          username: 'monitoring',
+          password: 'abc123',
+          custom_metrics: {
+            'query_is_missing_%s' => {
+              'query' => 'select * from fuzz',
+              'metrics' => { },
+            }
+          }
+        }}
+        it do
+          expect {
+            is_expected.to compile
+          }.to raise_error(/custom_metrics require %s for metric substitution/)
+        end
+      end
+
+      context 'with custom metric query' do
+        let(:params) {{
+          host: 'postgres1',
+          dbname: 'cats',
+          port: 4142,
+          username: 'monitoring',
+          password: 'abc123',
+          custom_metrics: {
+            'foo_gooo_bar_query' => {
+              'query' => 'select foo, %s from bar',
+              'metrics' => {
+                "gooo" => ["custom_metric.tag.gooo", "GAUGE"]
+              },
+              'descriptors' => [["foo", "custom_metric.tag.foo"]]
+            }
+          }
+        }}
+        it { is_expected.to compile }
+        it { should contain_file(conf_file).with_content(%r{^[^#]*custom_metrics:}) }
+        it { should contain_file(conf_file).with_content(%r{\s+query:\s*['"]?select foo, %s from bar['"]?}) }
+        it { should contain_file(conf_file).with_content(%r{\s+metrics:}) }
+        it { should contain_file(conf_file).with_content(%r{\s+"gooo":\s+\[custom_metric.tag.gooo, GAUGE\]}) }
+        it { should contain_file(conf_file).with_content(%r{\s+query.*\n\s+relation:\s*false}) }
+        it { should contain_file(conf_file).with_content(%r{\s+descriptors.*\n\s+-\s+\[foo, custom_metric.tag.foo\]}) }
+      end
     end
   end
 

templates/agent-conf.d/postgres.yaml.erb

@@ -41,3 +41,34 @@ instances:
     <%- end -%>
   <%- end -%>
 <% end -%>
+# https://help.datadoghq.com/hc/en-us/articles/208385813-Postgres-custom-metric-collection-explained
+# custom_metrics:
+#   - # Capture simple data
+#   query: SELECT name, address, %s from company where name = 'Paul'; # this query will be run and "%s" replaced with the parameters defined in the metrics section just below
+#   metrics:
+#       age: [postgresql.employee_age, GAUGE] # the value contained in column "age" will be captured and submitted as a gauge metric named "postgresql.employee.age"
+#       salary: [postgresql.employee_salary, GAUGE]
+#   relation: false #  when relation is not an empty list, it gathers per-relation metrics on top of that.
+#   descriptors:
+#       - [name, name] # captures the content of the "name" column as a tag for the 2 metrics defined
+#       - [address, localisation] # captures the content of "address" column as a tag and renames this tag "localisation"
+#
+<% if @custom_metrics and ! @custom_metrics.empty? -%>
+    custom_metrics:
+  <%- Array(@custom_metrics).each do |n, custom_metric| -%>
+      - query: <%= custom_metric["query"] %>
+        relation: <%= custom_metric["relation"]? "true" : "false" %>
+        metrics:
+    <%- Array(custom_metric["metrics"]).each do |metric_name, metric_descriptor| -%>
+          "<%= metric_name %>": [<%= metric_descriptor[0] %>, <%= metric_descriptor[1] %>]
+    <%- end -%>
+    <%- if custom_metric["descriptors"] == nil || custom_metric["descriptors"].empty? -%>
+        descriptors: []
+    <%- else -%>
+        descriptors:
+      <%- Array(custom_metric["descriptors"]).each do |descriptor| -%>
+          - [<%=descriptor[0]%>, <%=descriptor[1] %>]
+      <%- end -%>
+    <%- end -%>
+  <%- end -%>
+<% end -%>