Add pipeline creation duration histogram metric

doc/administration/monitoring/prometheus/gitlab_metrics.md

@@ -36,6 +36,7 @@ The following metrics are available:
 | `gitlab_cache_misses_total`                                    | Counter   |                   10.2 | Cache read miss                                                                                     | controller, action                                  |
 | `gitlab_cache_operation_duration_seconds`                      | Histogram |                   10.2 | Cache access time                                                                                   |                                                     |
 | `gitlab_cache_operations_total`                                | Counter   |                   12.2 | Cache operations by controller/action                                                               | controller, action, operation                       |
+| `gitlab_ci_pipeline_creation_duration_seconds`                 | Histogram |                   13.0 | Time in seconds it takes to create a CI/CD pipeline                                                 |                                                     |
 | `job_waiter_started_total`                                     | Counter   |                   12.9 | Number of batches of jobs started where a web request is waiting for the jobs to complete           | worker                                              |
 | `job_waiter_timeouts_total`                                    | Counter   |                   12.9 | Number of batches of jobs that timed out where a web request is waiting for the jobs to complete    | worker                                              |
 | `gitlab_database_transaction_seconds`                          | Histogram |                   12.1 | Time spent in database transactions, in seconds                                                     |                                                     |

lib/gitlab/ci/pipeline/chain/command.rb

@@ -76,6 +76,21 @@ module Gitlab
           def parent_pipeline
             bridge&.parent_pipeline
           end
+
+          def duration_histogram
+            strong_memoize(:duration_histogram) do
+              name = :gitlab_ci_pipeline_creation_duration_seconds
+              comment = 'Pipeline creation duration'
+              labels = {}
+              buckets = [0.01, 0.05, 0.1, 0.5, 1.0, 2.0, 5.0, 20.0, 50.0, 240.0]
+
+              Gitlab::Metrics.histogram(name, comment, labels, buckets)
+            end
+          end
+
+          def observe_creation_duration(duration)
+            duration_histogram.observe({}, duration.seconds)
+          end
         end
       end
     end

lib/gitlab/ci/pipeline/chain/sequence.rb

@@ -10,6 +10,7 @@ module Gitlab
             @command = command
             @sequence = sequence
             @completed = []
+            @start = Time.now
           end
 
           def build!
@@ -24,6 +25,8 @@ module Gitlab
 
             @pipeline.tap do
               yield @pipeline, self if block_given?
+
+              @command.observe_creation_duration(Time.now - @start)
             end
           end
 

spec/lib/gitlab/ci/pipeline/chain/sequence_spec.rb

@@ -5,11 +5,13 @@ require 'spec_helper'
 describe Gitlab::Ci::Pipeline::Chain::Sequence do
   let_it_be(:project) { create(:project) }
   let_it_be(:user) { create(:user) }
+
   let(:pipeline) { build_stubbed(:ci_pipeline) }
   let(:command) { Gitlab::Ci::Pipeline::Chain::Command.new }
   let(:first_step) { spy('first step') }
   let(:second_step) { spy('second step') }
   let(:sequence) { [first_step, second_step] }
+  let(:histogram) { spy('prometheus metric') }
 
   subject do
     described_class.new(pipeline, command, sequence)
@@ -52,5 +54,13 @@ describe Gitlab::Ci::Pipeline::Chain::Sequence do
     it 'returns a pipeline object' do
       expect(subject.build!).to eq pipeline
     end
+
+    it 'adds sequence duration to duration histogram' do
+      allow(command).to receive(:duration_histogram).and_return(histogram)
+
+      subject.build!
+
+      expect(histogram).to have_received(:observe)
+    end
   end
 end