Publish submission counts metrics to CloudWatch

Gemfile

@@ -62,7 +62,9 @@ gem "lograge"
 
 # For distributed tracing and telemetry
 gem "opentelemetry-exporter-otlp", "~> 0.34.0"
+gem "opentelemetry-exporter-otlp-metrics", "~> 0.10.0"
 gem "opentelemetry-instrumentation-all", "~> 0.94.0"
+gem "opentelemetry-metrics-sdk", "~> 0.15.0"
 gem "opentelemetry-propagator-xray", "~> 0.27.0"
 gem "opentelemetry-sdk", "~> 1.12"
 

Gemfile.lock

@@ -373,6 +373,15 @@ GEM
       opentelemetry-common (~> 0.20)
       opentelemetry-sdk (~> 1.10)
       opentelemetry-semantic_conventions
+    opentelemetry-exporter-otlp-metrics (0.10.0)
+      google-protobuf (>= 3.18, < 5.0)
+      googleapis-common-protos-types (~> 1.3)
+      opentelemetry-api (~> 1.1)
+      opentelemetry-common (~> 0.20)
+      opentelemetry-metrics-api (~> 0.2)
+      opentelemetry-metrics-sdk (~> 0.5)
+      opentelemetry-sdk (~> 1.2)
+      opentelemetry-semantic_conventions
     opentelemetry-helpers-mysql (0.6.0)
       opentelemetry-api (~> 1.7)
       opentelemetry-common (~> 0.21)
@@ -527,6 +536,12 @@ GEM
       opentelemetry-helpers-sql-processor
       opentelemetry-instrumentation-base (~> 0.25)
       opentelemetry-semantic_conventions (>= 1.8.0)
+    opentelemetry-metrics-api (0.6.0)
+      opentelemetry-api (~> 1.0)
+    opentelemetry-metrics-sdk (0.15.0)
+      opentelemetry-api (~> 1.1)
+      opentelemetry-metrics-api (~> 0.2)
+      opentelemetry-sdk (~> 1.2)
     opentelemetry-propagator-xray (0.27.0)
       opentelemetry-api (~> 1.7)
     opentelemetry-registry (0.6.0)
@@ -800,7 +815,9 @@ DEPENDENCIES
   omniauth-rails_csrf_protection
   omniauth_govuk_one_login!
   opentelemetry-exporter-otlp (~> 0.34.0)
+  opentelemetry-exporter-otlp-metrics (~> 0.10.0)
   opentelemetry-instrumentation-all (~> 0.94.0)
+  opentelemetry-metrics-sdk (~> 0.15.0)
   opentelemetry-propagator-xray (~> 0.27.0)
   opentelemetry-sdk (~> 1.12)
   pg (~> 1.6)
@@ -947,6 +964,7 @@ CHECKSUMS
   opentelemetry-api (1.10.0) sha256=99ee7c829b18381c31a817ee9bf6a160d737542d99cb8da55d443336d266bfa9
   opentelemetry-common (0.25.0) sha256=73915362e58d337fc92acbe1abfdaee1f725442527125fdb2af1420417f1149d
   opentelemetry-exporter-otlp (0.34.0) sha256=3b3cdf4329ba30f4389d849c7f13b8f9f983ecb4a030031c03997dffae1e2a60
+  opentelemetry-exporter-otlp-metrics (0.10.0) sha256=d8cbff9b8a3391eb61486b8be9b6ad74e3b9306a3c60fb4c906b28bc857167c8
   opentelemetry-helpers-mysql (0.6.0) sha256=7eeb5e6950c434775a8cf28b5fde4defc12e8b865c86479ce3119fcf593d9337
   opentelemetry-helpers-sql (0.4.0) sha256=b10e8c3a2cca28a98af951bbb3e4efdc59e68b25ba0825e055574af543420afb
   opentelemetry-helpers-sql-processor (0.5.0) sha256=b199241bc9451fcbd9f00b2f454830af19d4ca27c2219ea379c9b0d53cd0e0f1
@@ -996,6 +1014,8 @@ CHECKSUMS
   opentelemetry-instrumentation-sidekiq (0.29.0) sha256=b1d2a0cb9041a5e14239fe7c94d99e3dd07f870e2759460ab63592d7cdd8aadc
   opentelemetry-instrumentation-sinatra (0.30.0) sha256=b67301153420f43264a0c68cdb3ca5bd77467cf5054e57b83a2bf891aaaa0361
   opentelemetry-instrumentation-trilogy (0.69.0) sha256=0676dd720eeab284abfa52f273967442156fcac7084a1e1411373cf14ec026ad
+  opentelemetry-metrics-api (0.6.0) sha256=b9300821680a1370684098cb030c18423dd55909ea0206faadfa7bc47362df87
+  opentelemetry-metrics-sdk (0.15.0) sha256=611a9cd9f473c461095c7401b8c25f9774160d286a1acbfcbf044da2972aeada
   opentelemetry-propagator-xray (0.27.0) sha256=753f756c7ad3146f182d428b06041084eecc77769edfd280f365e0bc09b9c4d1
   opentelemetry-registry (0.6.0) sha256=5d3ed32ab9eee0fbdb30d4f0d0bb61ad11a4040b267b475ae815b80a8498a728
   opentelemetry-sdk (1.12.0) sha256=a224abe0c59023d41cb7ac1c634d9d28843907efcd045ed1ae320796c48b864b

app/services/form_submission_service.rb

@@ -104,6 +104,8 @@ def create_submission_record
 
     submission.deliveries.create!(delivery_schedule: :immediate)
 
+    Metrics::SubmissionCounter.record(form_id: form.id, form_name: form.name, mode:)
+
     submission
   end
 

app/services/metrics/submission_counter.rb

@@ -0,0 +1,44 @@
+module Metrics
+  class SubmissionCounter
+    METRIC_NAME = "SubmissionCount".freeze
+    METER_NAME = "forms-runner".freeze
+    METER_VERSION = "1.0".freeze
+
+    class << self
+      def record(form_id:, form_name:, mode:, meter_provider: OpenTelemetry.meter_provider)
+        return if mode.preview?
+
+        counter(meter_provider).add(
+          1,
+          attributes: metric_attributes(form_id:, form_name:),
+        )
+      end
+
+    private
+
+      def counter(meter_provider)
+        counters[meter_provider] ||= meter(meter_provider).create_counter(
+          METRIC_NAME,
+          unit: "1",
+          description: "Number of form submissions",
+        )
+      end
+
+      def counters
+        @counters ||= {}
+      end
+
+      def meter(meter_provider)
+        meter_provider.meter(METER_NAME, version: METER_VERSION)
+      end
+
+      def metric_attributes(form_id:, form_name:)
+        {
+          "Environment" => Settings.forms_env.downcase,
+          "FormId" => form_id.to_s,
+          "FormName" => form_name.to_s,
+        }
+      end
+    end
+  end
+end

config/initializers/opentelemetry.rb

@@ -1,5 +1,7 @@
 require "opentelemetry/sdk"
 require "opentelemetry/instrumentation/all"
+require "opentelemetry-metrics-sdk"
+require "opentelemetry-exporter-otlp-metrics"
 
 return unless ENV["ENABLE_OTEL"] == "true"
 
@@ -12,6 +14,14 @@
     c.id_generator = OpenTelemetry::Propagator::XRay::IDGenerator
   end
 
+  unless ENV.fetch("OTEL_METRICS_EXPORTER", "otlp") == "none"
+    c.add_metric_reader(
+      OpenTelemetry::SDK::Metrics::Export::PeriodicMetricReader.new(
+        exporter: OpenTelemetry::Exporter::OTLP::Metrics::MetricsExporter.new,
+      ),
+    )
+  end
+
   # Disable logging for Rake tasks to avoid cluttering output
   c.logger = Logger.new(File::NULL) if Rails.const_defined?(:Rake) && Rake.application.top_level_tasks.any?
 end

spec/services/form_submission_service_spec.rb

@@ -102,6 +102,16 @@
       expect(log_line["submission_reference"]).to eq(reference)
     end
 
+    it "records a submission count metric" do
+      expect(Metrics::SubmissionCounter).to receive(:record).with(
+        form_id: form.id,
+        form_name: form.name,
+        mode:,
+      )
+
+      service.submit
+    end
+
     shared_examples "logging" do
       it "logs submission" do
         allow(LogEventService).to receive(:log_submit).once

spec/services/metrics/submission_counter_spec.rb

@@ -0,0 +1,88 @@
+require "rails_helper"
+require "opentelemetry-metrics-sdk"
+
+describe Metrics::SubmissionCounter do
+  let(:meter_provider) { OpenTelemetry::SDK::Metrics::MeterProvider.new }
+  let(:metric_exporter) { OpenTelemetry::SDK::Metrics::Export::InMemoryMetricPullExporter.new }
+  let(:forms_env) { "test" }
+  let(:form_id) { 42 }
+  let(:form_name) { "Test Form" }
+  let(:mode) { Mode.new("form") }
+
+  before do
+    allow(Settings).to receive(:forms_env).and_return(forms_env)
+    meter_provider.add_metric_reader(metric_exporter)
+    described_class.send(:counters).clear
+  end
+
+  describe ".record" do
+    it "records a submission count metric" do
+      described_class.record(form_id:, form_name:, mode:, meter_provider:)
+
+      expect(exported_data_points).to contain_exactly(
+        have_attributes(
+          value: 1,
+          attributes: {
+            "Environment" => forms_env,
+            "FormId" => form_id.to_s,
+            "FormName" => form_name,
+          },
+        ),
+      )
+    end
+
+    context "when mode is preview" do
+      let(:mode) { Mode.new("preview-live") }
+
+      it "does not record a metric" do
+        described_class.record(form_id:, form_name:, mode:, meter_provider:)
+
+        expect(exported_data_points).to be_empty
+      end
+    end
+
+    it "accumulates counts for the same form" do
+      2.times { described_class.record(form_id:, form_name:, mode:, meter_provider:) }
+
+      expect(exported_data_points).to contain_exactly(
+        have_attributes(
+          value: 2,
+          attributes: {
+            "Environment" => forms_env,
+            "FormId" => form_id.to_s,
+            "FormName" => form_name,
+          },
+        ),
+      )
+    end
+
+    it "records separate counts per form" do
+      described_class.record(form_id:, form_name:, mode:, meter_provider:)
+      described_class.record(form_id: 99, form_name: "Other Form", mode:, meter_provider:)
+
+      expect(exported_data_points).to contain_exactly(
+        have_attributes(
+          value: 1,
+          attributes: {
+            "Environment" => forms_env,
+            "FormId" => form_id.to_s,
+            "FormName" => form_name,
+          },
+        ),
+        have_attributes(
+          value: 1,
+          attributes: {
+            "Environment" => forms_env,
+            "FormId" => "99",
+            "FormName" => "Other Form",
+          },
+        ),
+      )
+    end
+  end
+
+  def exported_data_points
+    metric_exporter.pull
+    metric_exporter.metric_snapshots.flat_map(&:data_points)
+  end
+end