Filters branch and path labels for metrics

changelogs/unreleased/48090-filter-sensitive-metric-labels.yml

+---
+title: Remove `path` and `branch` labels from metrics
+merge_request: 26744
+author:
+type: fixed

lib/gitlab/metrics/transaction.rb

@@ -8,6 +8,8 @@ module Gitlab
 
       # base labels shared among all transactions
       BASE_LABELS = { controller: nil, action: nil }.freeze
+      # labels that potentially contain sensitive information and will be filtered
+      FILTERED_LABELS = [:branch, :path].freeze
 
       THREAD_KEY = :_gitlab_metrics_transaction
 
@@ -64,7 +66,7 @@ module Gitlab
       end
 
       def add_metric(series, values, tags = {})
-        @metrics << Metric.new("#{::Gitlab::Metrics.series_prefix}#{series}", values, tags)
+        @metrics << Metric.new("#{::Gitlab::Metrics.series_prefix}#{series}", values, filter_tags(tags))
       end
 
       # Tracks a business level event
@@ -75,8 +77,9 @@ module Gitlab
       # event_name - The name of the event (e.g. "git_push").
       # tags - A set of tags to attach to the event.
       def add_event(event_name, tags = {})
-        self.class.transaction_metric(event_name, :counter, prefix: 'event_', use_feature_flag: true, tags: tags).increment(tags.merge(labels))
-        @metrics << Metric.new(EVENT_SERIES, { count: 1 }, tags.merge(event: event_name), :event)
+        filtered_tags = filter_tags(tags)
+        self.class.transaction_metric(event_name, :counter, prefix: 'event_', use_feature_flag: true, tags: filtered_tags).increment(filtered_tags.merge(labels))
+        @metrics << Metric.new(EVENT_SERIES, { count: 1 }, filtered_tags.merge(event: event_name), :event)
       end
 
       # Returns a MethodCall object for the given name.
@@ -164,6 +167,12 @@ module Gitlab
           end
         end
       end
+
+      private
+
+      def filter_tags(tags)
+        tags.without(*FILTERED_LABELS)
+      end
     end
   end
 end

spec/lib/gitlab/metrics/transaction_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Metrics::Transaction do
+  let(:transaction) { described_class.new }
+  let(:metric) { transaction.metrics[0] }
+
+  let(:sensitive_tags) do
+    {
+      path: 'private',
+      branch: 'sensitive'
+    }
+  end
+
+  shared_examples 'tag filter' do |sane_tags|
+    it 'filters potentially sensitive tags' do
+      expect(metric.tags).to eq(sane_tags)
+    end
+  end
+
+  describe '#duration' do
+    it 'returns the duration of a transaction in seconds' do
+      transaction.run { }
+
+      expect(transaction.duration).to be > 0
+    end
+  end
+
+  describe '#allocated_memory' do
+    it 'returns the allocated memory in bytes' do
+      transaction.run { 'a' * 32 }
+
+      expect(transaction.allocated_memory).to be_a_kind_of(Numeric)
+    end
+  end
+
+  describe '#run' do
+    it 'yields the supplied block' do
+      expect { |b| transaction.run(&b) }.to yield_control
+    end
+
+    it 'stores the transaction in the current thread' do
+      transaction.run do
+        expect(described_class.current).to eq(transaction)
+      end
+    end
+
+    it 'removes the transaction from the current thread upon completion' do
+      transaction.run { }
+
+      expect(described_class.current).to be_nil
+    end
+  end
+
+  describe '#add_metric' do
+    it 'adds a metric to the transaction' do
+      transaction.add_metric('foo', value: 1)
+
+      expect(metric.series).to eq('rails_foo')
+      expect(metric.tags).to eq({})
+      expect(metric.values).to eq(value: 1)
+    end
+
+    context 'with sensitive tags' do
+      before do
+        transaction
+          .add_metric('foo', { value: 1 }, **sensitive_tags.merge(sane: 'yes'))
+      end
+
+      it_behaves_like 'tag filter', sane: 'yes'
+    end
+  end
+
+  describe '#method_call_for' do
+    it 'returns a MethodCall' do
+      method = transaction.method_call_for('Foo#bar', :Foo, '#bar')
+
+      expect(method).to be_an_instance_of(Gitlab::Metrics::MethodCall)
+    end
+  end
+
+  describe '#increment' do
+    it 'increments a counter' do
+      transaction.increment(:time, 1)
+      transaction.increment(:time, 2)
+
+      values = metric_values(time: 3)
+
+      expect(transaction).to receive(:add_metric)
+        .with('transactions', values, {})
+
+      transaction.track_self
+    end
+  end
+
+  describe '#set' do
+    it 'sets a value' do
+      transaction.set(:number, 10)
+
+      values = metric_values(number: 10)
+
+      expect(transaction).to receive(:add_metric)
+        .with('transactions', values, {})
+
+      transaction.track_self
+    end
+  end
+
+  describe '#finish' do
+    it 'tracks the transaction details and submits them to Sidekiq' do
+      expect(transaction).to receive(:track_self)
+      expect(transaction).to receive(:submit)
+
+      transaction.finish
+    end
+  end
+
+  describe '#track_self' do
+    it 'adds a metric for the transaction itself' do
+      values = metric_values
+
+      expect(transaction).to receive(:add_metric)
+        .with('transactions', values, {})
+
+      transaction.track_self
+    end
+  end
+
+  describe '#submit' do
+    it 'submits the metrics to Sidekiq' do
+      transaction.track_self
+
+      expect(Gitlab::Metrics).to receive(:submit_metrics)
+        .with([an_instance_of(Hash)])
+
+      transaction.submit
+    end
+
+    it 'adds the action as a tag for every metric' do
+      allow(transaction)
+        .to receive(:labels)
+        .and_return(controller: 'Foo', action: 'bar')
+
+      transaction.track_self
+
+      hash = {
+        series: 'rails_transactions',
+        tags: { action: 'Foo#bar' },
+        values: metric_values,
+        timestamp: a_kind_of(Integer)
+      }
+
+      expect(Gitlab::Metrics).to receive(:submit_metrics)
+        .with([hash])
+
+      transaction.submit
+    end
+
+    it 'does not add an action tag for events' do
+      allow(transaction)
+        .to receive(:labels)
+        .and_return(controller: 'Foo', action: 'bar')
+
+      transaction.add_event(:meow)
+
+      hash = {
+        series: 'events',
+        tags: { event: :meow },
+        values: { count: 1 },
+        timestamp: a_kind_of(Integer)
+      }
+
+      expect(Gitlab::Metrics).to receive(:submit_metrics)
+        .with([hash])
+
+      transaction.submit
+    end
+  end
+
+  describe '#add_event' do
+    it 'adds a metric' do
+      transaction.add_event(:meow)
+
+      expect(metric).to be_an_instance_of(Gitlab::Metrics::Metric)
+    end
+
+    it "does not prefix the metric's series name" do
+      transaction.add_event(:meow)
+
+      expect(metric.series).to eq(described_class::EVENT_SERIES)
+    end
+
+    it 'tracks a counter for every event' do
+      transaction.add_event(:meow)
+
+      expect(metric.values).to eq(count: 1)
+    end
+
+    it 'tracks the event name' do
+      transaction.add_event(:meow)
+
+      expect(metric.tags).to eq(event: :meow)
+    end
+
+    it 'allows tracking of custom tags' do
+      transaction.add_event(:meow, animal: 'cat')
+
+      expect(metric.tags).to eq(event: :meow, animal: 'cat')
+    end
+
+    context 'with sensitive tags' do
+      before do
+        transaction.add_event(:meow, **sensitive_tags.merge(sane: 'yes'))
+      end
+
+      it_behaves_like 'tag filter', event: :meow, sane: 'yes'
+    end
+  end
+
+  private
+
+  def metric_values(opts = {})
+    {
+      duration: 0.0,
+      allocated_memory: a_kind_of(Numeric)
+    }.merge(opts)
+  end
+end