Add path to gitab managed apps logs for cluster

When presenting list of clusters we should include link to
log explorer for gitlab managed apps if user can access it

app/helpers/environments_helper.rb

@@ -36,7 +36,8 @@ module EnvironmentsHelper
       "environment-name": environment.name,
       "environments-path": project_environments_path(project, format: :json),
       "environment-id": environment.id,
-      "cluster-applications-documentation-path" => help_page_path('user/clusters/applications.md', anchor: 'elastic-stack')
+      "cluster-applications-documentation-path" => help_page_path('user/clusters/applications.md', anchor: 'elastic-stack'),
+      "clusters-path": project_clusters_path(project, format: :json)
     }
   end
 

app/presenters/clusters/cluster_presenter.rb

@@ -2,6 +2,7 @@
 
 module Clusters
   class ClusterPresenter < Gitlab::View::Presenter::Delegated
+    include ::Gitlab::Utils::StrongMemoize
     include ActionView::Helpers::SanitizeHelper
     include ActionView::Helpers::UrlHelper
     include IconsHelper
@@ -60,6 +61,12 @@ module Clusters
       end
     end
 
+    def gitlab_managed_apps_logs_path
+      return unless logs_project && can_read_cluster?
+
+      project_logs_path(logs_project, cluster_id: cluster.id)
+    end
+
     def read_only_kubernetes_platform_fields?
       !cluster.provided_by_user?
     end
@@ -85,6 +92,16 @@ module Clusters
       ActionController::Base.helpers.image_path(path)
     end
 
+    # currently log explorer is only available in the scope of the project
+    # for group and instance level cluster selected project does not affects
+    # fetching logs from gitlab managed apps namespace, therefore any project
+    # available to user will be sufficient.
+    def logs_project
+      strong_memoize(:logs_project) do
+        cluster.all_projects.first
+      end
+    end
+
     def clusterable
       if cluster.group_type?
         cluster.group

app/serializers/cluster_entity.rb

@@ -16,4 +16,8 @@ class ClusterEntity < Grape::Entity
   expose :path do |cluster|
     Clusters::ClusterPresenter.new(cluster).show_path # rubocop: disable CodeReuse/Presenter
   end
+
+  expose :gitlab_managed_apps_logs_path do |cluster|
+    Clusters::ClusterPresenter.new(cluster, current_user: request.current_user).gitlab_managed_apps_logs_path # rubocop: disable CodeReuse/Presenter
+  end
 end

app/serializers/cluster_serializer.rb

@@ -10,6 +10,7 @@ class ClusterSerializer < BaseSerializer
         :cluster_type,
         :enabled,
         :environment_scope,
+        :gitlab_managed_apps_logs_path,
         :name,
         :nodes,
         :path,

spec/helpers/environments_helper_spec.rb

@@ -114,4 +114,18 @@ RSpec.describe EnvironmentsHelper do
       expect(subject).to eq(true)
     end
   end
+
+  describe '#environment_logs_data' do
+    it 'returns logs data' do
+      expected_data = {
+        "environment-name": environment.name,
+        "environments-path": project_environments_path(project, format: :json),
+        "environment-id": environment.id,
+        "cluster-applications-documentation-path" => help_page_path('user/clusters/applications.md', anchor: 'elastic-stack'),
+        "clusters-path": project_clusters_path(project, format: :json)
+      }
+
+      expect(helper.environment_logs_data(project, environment)).to eq(expected_data)
+    end
+  end
 end

spec/presenters/clusters/cluster_presenter_spec.rb

@@ -289,4 +289,74 @@ RSpec.describe Clusters::ClusterPresenter do
       it_behaves_like 'cluster health data'
     end
   end
+
+  describe '#gitlab_managed_apps_logs_path' do
+    context 'user can read logs' do
+      let(:project) { cluster.project }
+
+      before do
+        project.add_maintainer(user)
+      end
+
+      it 'returns path to logs' do
+        expect(presenter.gitlab_managed_apps_logs_path).to eq project_logs_path(project, cluster_id: cluster.id)
+      end
+    end
+
+    context 'group cluster' do
+      let(:cluster) { create(:cluster, cluster_type: :group_type, groups: [group]) }
+      let(:group) { create(:group, name: 'Foo') }
+
+      context 'user can read logs' do
+        before do
+          group.add_maintainer(user)
+        end
+
+        context 'there are projects within group' do
+          let!(:project) { create(:project, namespace: group) }
+
+          it 'returns path to logs' do
+            expect(presenter.gitlab_managed_apps_logs_path).to eq project_logs_path(project, cluster_id: cluster.id)
+          end
+        end
+
+        context 'there are no projects within group' do
+          it 'returns nil' do
+            expect(presenter.gitlab_managed_apps_logs_path).to be_nil
+          end
+        end
+      end
+    end
+
+    context 'instance cluster' do
+      let(:cluster) { create(:cluster, cluster_type: :instance_type) }
+      let!(:project) { create(:project) }
+      let(:user) { create(:admin) }
+
+      before do
+        project.add_maintainer(user)
+        stub_feature_flags(user_mode_in_session: false)
+      end
+
+      context 'user can read logs' do
+        it 'returns path to logs' do
+          expect(presenter.gitlab_managed_apps_logs_path).to eq project_logs_path(project, cluster_id: cluster.id)
+        end
+      end
+    end
+
+    context 'user can NOT read logs' do
+      let(:cluster) { create(:cluster, cluster_type: :instance_type) }
+      let!(:project) { create(:project) }
+
+      before do
+        project.add_developer(user)
+        stub_feature_flags(user_mode_in_session: false)
+      end
+
+      it 'returns nil' do
+        expect(presenter.gitlab_managed_apps_logs_path).to be_nil
+      end
+    end
+  end
 end

spec/serializers/cluster_entity_spec.rb

@@ -3,8 +3,13 @@
 require 'spec_helper'
 
 RSpec.describe ClusterEntity do
+  include Gitlab::Routing.url_helpers
+
   describe '#as_json' do
-    subject { described_class.new(cluster).as_json }
+    let(:user) { nil }
+    let(:request) { EntityRequest.new({ current_user: user }) }
+
+    subject { described_class.new(cluster, request: request).as_json }
 
     context 'when provider type is gcp' do
       let(:cluster) { create(:cluster, :instance, provider_type: :gcp, provider_gcp: provider) }
@@ -40,7 +45,7 @@ RSpec.describe ClusterEntity do
     context 'when no application has been installed' do
       let(:cluster) { create(:cluster, :instance) }
 
-      subject { described_class.new(cluster).as_json[:applications]}
+      subject { described_class.new(cluster, request: request).as_json[:applications]}
 
       it 'contains helm as not_installable' do
         expect(subject).not_to be_empty
@@ -50,5 +55,28 @@ RSpec.describe ClusterEntity do
         expect(helm[:status]).to eq(:not_installable)
       end
     end
+
+    context 'gitlab_managed_apps_logs_path' do
+      let(:cluster) { create(:cluster, :project) }
+      let(:user) { create(:user) }
+
+      subject { described_class.new(cluster, request: request).as_json }
+
+      before do
+        allow_next_instance_of(Clusters::ClusterPresenter) do |presenter|
+          allow(presenter).to receive(:show_path).and_return(nil)
+        end
+      end
+
+      it 'return projects log explorer path' do
+        log_explorer_path = project_logs_path(cluster.project, cluster_id: cluster.id)
+
+        expect_next_instance_of(Clusters::ClusterPresenter, cluster, current_user: user) do |presenter|
+          expect(presenter).to receive(:gitlab_managed_apps_logs_path).and_return(log_explorer_path)
+        end
+
+        expect(subject[:gitlab_managed_apps_logs_path]).to eq(log_explorer_path)
+      end
+    end
   end
 end

spec/serializers/cluster_serializer_spec.rb

@@ -6,13 +6,14 @@ RSpec.describe ClusterSerializer do
   let(:cluster) { create(:cluster, :project, provider_type: :user) }
 
   describe '#represent_list' do
-    subject { described_class.new.represent_list(cluster).keys }
+    subject { described_class.new(current_user: nil).represent_list(cluster).keys }
 
     it 'serializes attrs correctly' do
       is_expected.to contain_exactly(
         :cluster_type,
         :enabled,
         :environment_scope,
+        :gitlab_managed_apps_logs_path,
         :name,
         :nodes,
         :path,
@@ -22,7 +23,7 @@ RSpec.describe ClusterSerializer do
   end
 
   describe '#represent_status' do
-    subject { described_class.new.represent_status(cluster).keys }
+    subject { described_class.new(current_user: nil).represent_status(cluster).keys }
 
     context 'when provider type is gcp and cluster is errored' do
       let(:cluster) do