Implement error tracking controller

The frontend part will be done in a different MR.

app/controllers/projects/error_tracking_controller.rb

+# frozen_string_literal: true
+
+class Projects::ErrorTrackingController < Projects::ApplicationController
+  before_action :check_feature_flag!
+  before_action :authorize_read_sentry_issue!
+  before_action :push_feature_flag_to_frontend
+
+  POLLING_INTERVAL = 10_000
+
+  def index
+    respond_to do |format|
+      format.html
+      format.json do
+        set_polling_interval
+        render_index_json
+      end
+    end
+  end
+
+  private
+
+  def render_index_json
+    service = ErrorTracking::ListIssuesService.new(project, current_user)
+    result = service.execute
+
+    unless result[:status] == :success
+      return render json: { message: result[:message] },
+                    status: result[:http_status] || :bad_request
+    end
+
+    render json: {
+      errors: serialize_errors(result[:issues]),
+      external_url: service.external_url
+    }
+  end
+
+  def set_polling_interval
+    Gitlab::PollingInterval.set_header(response, interval: POLLING_INTERVAL)
+  end
+
+  def serialize_errors(errors)
+    ErrorTracking::ErrorSerializer
+      .new(project: project, user: current_user)
+      .represent(errors)
+  end
+
+  def check_feature_flag!
+    render_404 unless Feature.enabled?(:error_tracking, project)
+  end
+
+  def push_feature_flag_to_frontend
+    push_frontend_feature_flag(:error_tracking, current_user)
+  end
+end

app/models/error_tracking/project_error_tracking_setting.rb

@@ -2,6 +2,10 @@
 
 module ErrorTracking
   class ProjectErrorTrackingSetting < ActiveRecord::Base
+    include ReactiveCaching
+
+    self.reactive_cache_key = ->(setting) { [setting.class.model_name.singular, setting.project_id] }
+
     belongs_to :project
 
     validates :api_url, length: { maximum: 255 }, public_url: true, url: { enforce_sanitization: true }
@@ -13,23 +17,38 @@ module ErrorTracking
       key: Settings.attr_encrypted_db_key_base_truncated,
       algorithm: 'aes-256-gcm'
 
+    after_save :clear_reactive_cache!
+
     def sentry_client
       Sentry::Client.new(api_url, token)
     end
 
     def sentry_external_url
-      extract_external_url
+      self.class.extract_sentry_external_url(api_url)
     end
 
-    private
+    def list_sentry_issues(opts = {})
+      with_reactive_cache('list_issues', opts.stringify_keys) do |result|
+        { issues: result }
+      end
+    end
+
+    def calculate_reactive_cache(request, opts)
+      case request
+      when 'list_issues'
+        sentry_client.list_issues(**opts.symbolize_keys)
+      end
+    end
 
     # http://HOST/api/0/projects/ORG/PROJECT
     # ->
     # http://HOST/ORG/PROJECT
-    def extract_external_url
-      api_url.sub('api/0/projects/', '')
+    def self.extract_sentry_external_url(url)
+      url.sub('api/0/projects/', '')
     end
 
+    private
+
     def validate_api_url_path
       unless URI(api_url).path.starts_with?('/api/0/projects')
         errors.add(:api_url, 'path needs to start with /api/0/projects')

app/serializers/error_tracking/error_entity.rb

+# frozen_string_literal: true
+
+module ErrorTracking
+  class ErrorEntity < Grape::Entity
+    expose :id, :title, :type, :user_count, :count,
+      :first_seen, :last_seen, :message, :culprit,
+      :external_url, :project_id, :project_name, :project_slug,
+      :short_id, :status, :frequency
+  end
+end

app/serializers/error_tracking/error_serializer.rb

+# frozen_string_literal: true
+
+module ErrorTracking
+  class ErrorSerializer < BaseSerializer
+    entity ErrorEntity
+  end
+end

app/services/error_tracking/list_issues_service.rb

@@ -2,15 +2,22 @@
 
 module ErrorTracking
   class ListIssuesService < ::BaseService
-    DEFAULT_ISSUE_STATUS = 'unresolved'.freeze
+    DEFAULT_ISSUE_STATUS = 'unresolved'
     DEFAULT_LIMIT = 20
 
     def execute
-      return error('not enabled') unless valid?
-      return error('access denied') unless can?(current_user, :read_sentry_issue, project)
+      return error('not enabled') unless enabled?
+      return error('access denied') unless can_read?
 
-      issues = sentry_client.list_issues(issue_status: issue_status, limit: limit)
-      success(issues: issues)
+      result = project_error_tracking_setting
+        .list_sentry_issues(issue_status: issue_status, limit: limit)
+
+      # our results are not yet ready
+      unless result
+        return error('not ready', :no_content)
+      end
+
+      success(issues: result[:issues])
     end
 
     def external_url
@@ -31,12 +38,12 @@ module ErrorTracking
       params[:limit] || DEFAULT_LIMIT
     end
 
-    def valid?
+    def enabled?
       project_error_tracking_setting&.enabled?
     end
 
-    def sentry_client
-      project_error_tracking_setting&.sentry_client
+    def can_read?
+      can?(current_user, :read_sentry_issue, project)
     end
   end
 end

app/views/projects/error_tracking/index.html.haml

+- page_title _('Errors')

config/routes/project.rb

@@ -538,6 +538,8 @@ constraints(::Constraints::ProjectUrlConstrainer.new) do
         end
       end
 
+      resources :error_tracking, only: [:index], controller: :error_tracking
+
       # Since both wiki and repository routing contains wildcard characters
       # its preferable to keep it below all other project routes
       draw :wiki

lib/sentry/client.rb

@@ -61,7 +61,13 @@ module Sentry
     end
 
     def issue_url(id)
-      "#{issues_api_url}#{id}/"
+      issues_url = @url + "/issues/#{id}"
+      issues_url = ErrorTracking::ProjectErrorTrackingSetting.extract_sentry_external_url(issues_url)
+
+      uri = URI(issues_url)
+      uri.path.squeeze!('/')
+
+      uri.to_s
     end
 
     def map_to_error(issue)

spec/controllers/projects/error_tracking_controller_spec.rb

+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Projects::ErrorTrackingController do
+  set(:project) { create(:project) }
+  set(:user) { create(:user) }
+
+  before do
+    sign_in(user)
+    project.add_maintainer(user)
+  end
+
+  describe 'GET #index' do
+    describe 'html' do
+      it 'renders index with 200 status code' do
+        get :index, params: project_params
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response).to render_template(:index)
+      end
+
+      context 'with feature flag disabled' do
+        before do
+          stub_feature_flags(error_tracking: false)
+        end
+
+        it 'returns 404' do
+          get :index, params: project_params
+
+          expect(response).to have_gitlab_http_status(:not_found)
+        end
+      end
+
+      context 'with insufficient permissions' do
+        before do
+          project.add_guest(user)
+        end
+
+        it 'returns 404' do
+          get :index, params: project_params
+
+          expect(response).to have_gitlab_http_status(:not_found)
+        end
+      end
+
+      context 'with an anonymous user' do
+        before do
+          sign_out(user)
+        end
+
+        it 'redirects to sign-in page' do
+          get :index, params: project_params
+
+          expect(response).to redirect_to(new_user_session_path)
+        end
+      end
+    end
+
+    describe 'format json' do
+      shared_examples 'no data' do
+        it 'returns no data' do
+          get :index, params: project_params(format: :json)
+
+          expect(response).to have_gitlab_http_status(:ok)
+          expect(response).to match_response_schema('error_tracking/index')
+          expect(json_response['external_url']).to be_nil
+          expect(json_response['errors']).to eq([])
+        end
+      end
+
+      let(:list_issues_service) { spy(:list_issues_service) }
+      let(:external_url) { 'http://example.com' }
+
+      before do
+        expect(ErrorTracking::ListIssuesService)
+          .to receive(:new).with(project, user)
+          .and_return(list_issues_service)
+      end
+
+      context 'service result is successful' do
+        before do
+          expect(list_issues_service).to receive(:execute)
+            .and_return(status: :success, issues: [error])
+          expect(list_issues_service).to receive(:external_url)
+            .and_return(external_url)
+        end
+
+        let(:error) { build(:error_tracking_error) }
+
+        it 'returns a list of errors' do
+          get :index, params: project_params(format: :json)
+
+          expect(response).to have_gitlab_http_status(:ok)
+          expect(response).to match_response_schema('error_tracking/index')
+          expect(json_response['external_url']).to eq(external_url)
+          expect(json_response['errors']).to eq([error].as_json)
+        end
+      end
+
+      context 'service result is erroneous' do
+        let(:error_message) { 'error message' }
+
+        context 'without http_status' do
+          before do
+            expect(list_issues_service).to receive(:execute)
+              .and_return(status: :error, message: error_message)
+          end
+
+          it 'returns 400 with message' do
+            get :index, params: project_params(format: :json)
+
+            expect(response).to have_gitlab_http_status(:bad_request)
+            expect(json_response['message']).to eq(error_message)
+          end
+        end
+
+        context 'with explicit http_status' do
+          let(:http_status) { :no_content }
+
+          before do
+            expect(list_issues_service).to receive(:execute)
+              .and_return(status: :error, message: error_message, http_status: http_status)
+          end
+
+          it 'returns http_status with message' do
+            get :index, params: project_params(format: :json)
+
+            expect(response).to have_gitlab_http_status(http_status)
+            expect(json_response['message']).to eq(error_message)
+          end
+        end
+      end
+    end
+  end
+
+  private
+
+  def project_params(opts = {})
+    opts.reverse_merge(namespace_id: project.namespace, project_id: project)
+  end
+end

spec/factories/error_tracking/error.rb

+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :error_tracking_error, class: Gitlab::ErrorTracking::Error do
+    id 'id'
+    title 'title'
+    type 'error'
+    user_count 1
+    count 2
+    first_seen { Time.now }
+    last_seen { Time.now }
+    message 'message'
+    culprit 'culprit'
+    external_url 'http://example.com/id'
+    project_id 'project1'
+    project_name 'project name'
+    project_slug 'project_name'
+    short_id 'ID'
+    status 'unresolved'
+    frequency []
+
+    skip_create
+  end
+end

spec/fixtures/api/schemas/error_tracking/error.json

+{
+  "type": "object",
+  "required" : [
+    "external_url",
+    "last_seen",
+    "message",
+    "type"
+  ],
+  "properties" : {
+    "id": { "type": "string"},
+    "first_seen": { "type": "string", "format": "date-time" },
+    "last_seen": { "type": "string", "format": "date-time" },
+    "type": { "type": "string" },
+    "message": { "type": "string" },
+    "culprit": { "type": "string" },
+    "count": { "type": "integer"},
+    "external_url": { "type": "string" },
+    "user_count": { "type": "integer"}
+  },
+  "additionalProperties": true
+}

spec/fixtures/api/schemas/error_tracking/index.json

+{
+  "type": "object",
+  "required": [
+    "external_url",
+    "errors"
+  ],
+  "properties": {
+    "external_url": { "type": ["string", "null"] },
+    "errors": {
+      "type": "array",
+      "items": { "$ref": "error.json" }
+    }
+  },
+  "additionalProperties": false
+}

spec/lib/sentry/client_spec.rb

@@ -55,7 +55,7 @@ describe Sentry::Client do
 
       context 'external_url' do
         it 'is constructed correctly' do
-          expect(subject[0].external_url).to eq('https://sentrytest.gitlab.com/api/0/projects/sentry-org/sentry-project/issues/11/')
+          expect(subject[0].external_url).to eq('https://sentrytest.gitlab.com/sentry-org/sentry-project/issues/11')
         end
       end
     end

spec/models/error_tracking/project_error_tracking_setting_spec.rb

@@ -3,6 +3,8 @@
 require 'spec_helper'
 
 describe ErrorTracking::ProjectErrorTrackingSetting do
+  include ReactiveCachingHelpers
+
   set(:project) { create(:project) }
 
   subject { create(:project_error_tracking_setting, project: project) }
@@ -48,10 +50,16 @@ describe ErrorTracking::ProjectErrorTrackingSetting do
   describe '#sentry_external_url' do
     let(:sentry_url) { 'https://sentrytest.gitlab.com/api/0/projects/sentry-org/sentry-project' }
 
-    it 'returns the correct url' do
+    before do
       subject.api_url = sentry_url
+    end
+
+    it 'returns the correct url' do
+      expect(subject.class).to receive(:extract_sentry_external_url).with(sentry_url).and_call_original
+
+      result = subject.sentry_external_url
 
-      expect(subject.sentry_external_url).to eq('https://sentrytest.gitlab.com/sentry-org/sentry-project')
+      expect(result).to eq('https://sentrytest.gitlab.com/sentry-org/sentry-project')
     end
   end
 
@@ -60,4 +68,42 @@ describe ErrorTracking::ProjectErrorTrackingSetting do
       expect(subject.sentry_client).to be_a(Sentry::Client)
     end
   end
+
+  describe '#list_sentry_issues' do
+    let(:issues) { [:list, :of, :issues] }
+
+    let(:opts) do
+      { issue_status: 'unresolved', limit: 10 }
+    end
+
+    let(:result) do
+      subject.list_sentry_issues(**opts)
+    end
+
+    context 'when cached' do
+      let(:sentry_client) { spy(:sentry_client) }
+
+      before do
+        stub_reactive_cache(subject, issues, opts)
+        synchronous_reactive_cache(subject)
+
+        expect(subject).to receive(:sentry_client).and_return(sentry_client)
+      end
+
+      it 'returns cached issues' do
+        expect(sentry_client).to receive(:list_issues).with(opts)
+          .and_return(issues)
+
+        expect(result).to eq(issues: issues)
+      end
+    end
+
+    context 'when not cached' do
+      it 'returns nil' do
+        expect(subject).not_to receive(:sentry_client)
+
+        expect(result).to be_nil
+      end
+    end
+  end
 end

spec/services/error_tracking/list_issues_service_spec.rb

@@ -8,7 +8,7 @@ describe ErrorTracking::ListIssuesService do
 
   let(:sentry_url) { 'https://sentrytest.gitlab.com/api/0/projects/sentry-org/sentry-project' }
   let(:token) { 'test-token' }
-  let(:client) { Sentry::Client.new(sentry_url, token) }
+  let(:result) { subject.execute }
 
   let(:error_tracking_setting) do
     create(:project_error_tracking_setting, api_url: sentry_url, token: token, project: project)
@@ -24,16 +24,29 @@ describe ErrorTracking::ListIssuesService do
 
   describe '#execute' do
     context 'with authorized user' do
+      context 'when list_sentry_issues returns issues' do
+        let(:issues) { [:list, :of, :issues] }
+
         before do
-        expect(error_tracking_setting).to receive(:sentry_client).and_return(client)
+          expect(error_tracking_setting)
+            .to receive(:list_sentry_issues).and_return(issues: issues)
         end
 
-      it 'calls sentry client' do
-        expect(client).to receive(:list_issues).and_return([])
+        it 'returns the issues' do
+          expect(result).to eq(status: :success, issues: issues)
+        end
+      end
 
-        result = subject.execute
+      context 'when list_sentry_issues returns nil' do
+        before do
+          expect(error_tracking_setting)
+            .to receive(:list_sentry_issues).and_return(nil)
+        end
 
-        expect(result).to include(status: :success)
+        it 'result is not ready' do
+          expect(result).to eq(
+            status: :error, http_status: :no_content, message: 'not ready')
+        end
       end
     end