Drop health checks from WebExporter

These endpoints have been deprecated for a while
and are not in use anymore.

Health checks are served from HealthController now.

config/initializers/7_prometheus_metrics.rb

@@ -95,13 +95,6 @@ if Gitlab::Runtime.web_server?
     Gitlab::Metrics::Exporter::WebExporter.instance.start
   end
 
-  # DEPRECATED: TO BE REMOVED
-  # This is needed to implement blackout period of `web_exporter`
-  # https://gitlab.com/gitlab-org/gitlab/issues/35343#note_238479057
-  Gitlab::Cluster::LifecycleEvents.on_before_blackout_period do
-    Gitlab::Metrics::Exporter::WebExporter.instance.mark_as_not_running!
-  end
-
   Gitlab::Cluster::LifecycleEvents.on_before_graceful_shutdown do
     # We need to ensure that before we re-exec or shutdown server
     # we do stop the exporter

lib/gitlab/metrics/exporter/base_exporter.rb

@@ -9,8 +9,6 @@ module Gitlab
       class BaseExporter < Daemon
         attr_reader :server
 
-        attr_accessor :readiness_checks
-
         def initialize(settings, log_enabled:, log_file:, gc_requests: false, **options)
           super(**options)
 
@@ -85,7 +83,7 @@ module Gitlab
         end
 
         def readiness_probe
-          ::Gitlab::HealthChecks::Probes::Collection.new(*readiness_checks)
+          ::Gitlab::HealthChecks::Probes::Collection.new
         end
 
         def liveness_probe

lib/gitlab/metrics/exporter/web_exporter.rb

@@ -4,17 +4,6 @@ module Gitlab
   module Metrics
     module Exporter
       class WebExporter < BaseExporter
-        ExporterCheck = Struct.new(:exporter) do
-          def readiness
-            Gitlab::HealthChecks::Result.new(
-              'web_exporter', exporter.running)
-          end
-
-          def available?
-            true
-          end
-        end
-
         RailsMetricsInitializer = Struct.new(:app) do
           def call(env)
             Gitlab::Metrics::RailsSlis.initialize_request_slis_if_needed!
@@ -23,24 +12,9 @@ module Gitlab
           end
         end
 
-        attr_reader :running
-
         # This exporter is always run on master process
         def initialize(**options)
           super(Settings.monitoring.web_exporter, log_enabled: true, log_file: 'web_exporter.log', **options)
-
-          # DEPRECATED:
-          # these `readiness_checks` are deprecated
-          # as presenting no value in a way how we run
-          # application: https://gitlab.com/gitlab-org/gitlab/issues/35343
-          self.readiness_checks = [
-            WebExporter::ExporterCheck.new(self),
-            Gitlab::HealthChecks::PumaCheck
-          ]
-        end
-
-        def mark_as_not_running!
-          @running = false
         end
 
         private
@@ -53,16 +27,6 @@ module Gitlab
             run app
           end
         end
-
-        def start_working
-          @running = true
-          super
-        end
-
-        def stop_working
-          mark_as_not_running!
-          super
-        end
       end
     end
   end

spec/lib/gitlab/metrics/exporter/web_exporter_spec.rb

@@ -4,7 +4,6 @@ require 'spec_helper'
 
 RSpec.describe Gitlab::Metrics::Exporter::WebExporter do
   let(:exporter) { described_class.new }
-  let(:readiness_probe) { exporter.send(:readiness_probe).execute }
 
   before do
     stub_config(
@@ -25,12 +24,6 @@ RSpec.describe Gitlab::Metrics::Exporter::WebExporter do
   end
 
   context 'when running server', :prometheus do
-    it 'readiness probe returns succesful status' do
-      expect(readiness_probe.http_status).to eq(200)
-      expect(readiness_probe.json).to include(status: 'ok')
-      expect(readiness_probe.json).to include('web_exporter' => [{ 'status': 'ok' }])
-    end
-
     it 'initializes request metrics' do
       expect(Gitlab::Metrics::RailsSlis).to receive(:initialize_request_slis_if_needed!).and_call_original
 
@@ -40,14 +33,4 @@ RSpec.describe Gitlab::Metrics::Exporter::WebExporter do
       expect(response.body).to include('gitlab_sli:rails_request_apdex')
     end
   end
-
-  describe '#mark_as_not_running!' do
-    it 'readiness probe returns a failure status', :prometheus do
-      exporter.mark_as_not_running!
-
-      expect(readiness_probe.http_status).to eq(503)
-      expect(readiness_probe.json).to include(status: 'failed')
-      expect(readiness_probe.json).to include('web_exporter' => [{ 'status': 'failed' }])
-    end
-  end
 end