Show health graphs on group-level

Tweak cluster helper and refactor its specs.

app/helpers/clusters_helper.rb

@@ -20,9 +20,4 @@ module ClustersHelper
     !cluster.provider.legacy_abac?
   end
-
-  # EE overrides this
-  def show_cluster_health_graphs?(cluster)
-    false
-  end
 end

app/models/clusters/cluster.rb

@@ -10,14 +10,14 @@ module Clusters
     PROJECT_ONLY_APPLICATIONS = {
       Applications::Jupyter.application_name => Applications::Jupyter,
-      Applications::Knative.application_name => Applications::Knative,
-      Applications::Prometheus.application_name => Applications::Prometheus
+      Applications::Knative.application_name => Applications::Knative
     }.freeze
     APPLICATIONS = {
       Applications::Helm.application_name => Applications::Helm,
       Applications::Ingress.application_name => Applications::Ingress,
       Applications::CertManager.application_name => Applications::CertManager,
-      Applications::Runner.application_name => Applications::Runner
+      Applications::Runner.application_name => Applications::Runner,
+      Applications::Prometheus.application_name => Applications::Prometheus
     }.merge(PROJECT_ONLY_APPLICATIONS).freeze
     DEFAULT_ENVIRONMENT = '*'.freeze
     KUBE_INGRESS_BASE_DOMAIN = 'KUBE_INGRESS_BASE_DOMAIN'.freeze

app/presenters/clusterable_presenter.rb

@@ -52,6 +52,10 @@ class ClusterablePresenter < Gitlab::View::Presenter::Delegated
     raise NotImplementedError
   end
+  def clusters_path(params = {})
+    raise NotImplementedError
+  end
+
   def empty_state_help_text
     nil
   end

app/presenters/group_clusterable_presenter.rb

@@ -24,6 +24,11 @@ class GroupClusterablePresenter < ClusterablePresenter
     group_cluster_path(clusterable, cluster, params)
   end
+  override :clusters_path
+  def clusters_path(params = {})
+    group_clusters_path(clusterable, params)
+  end
+
   override :empty_state_help_text
   def empty_state_help_text
     s_('ClusterIntegration|Adding an integration to your group will share the cluster across all your projects.')

app/presenters/project_clusterable_presenter.rb

@@ -24,6 +24,11 @@ class ProjectClusterablePresenter < ClusterablePresenter
     project_cluster_path(clusterable, cluster, params)
   end
+  override :clusters_path
+  def clusters_path(params = {})
+    project_clusters_path(clusterable, params)
+  end
+
   override :sidebar_text
   def sidebar_text
     s_('ClusterIntegration|With a Kubernetes cluster associated to this project, you can use review apps, deploy your applications, run your pipelines, and much more in an easy way.')

app/views/clusters/clusters/show.html.haml

@@ -34,7 +34,7 @@
     = render 'banner'
     = render 'form'
-  = render_if_exists 'projects/clusters/prometheus_graphs' if show_cluster_health_graphs?(@cluster)
+  = render_if_exists 'projects/clusters/prometheus_graphs'
   .cluster-applications-table#js-cluster-applications

doc/user/group/clusters/index.md

@@ -28,6 +28,7 @@ deployments.
 | [Helm Tiller](https://docs.helm.sh)                                        | 11.6+          | Helm is a package manager for Kubernetes and is required to install all the other applications. It is installed in its own pod inside the cluster which can run the `helm` CLI in a safe environment. | n/a |
 | [Ingress](https://kubernetes.io/docs/concepts/services-networking/ingress) | 11.6+          | Ingress can provide load balancing, SSL termination, and name-based virtual hosting. It acts as a web proxy for your applications and is useful if you want to use [Auto DevOps](../../../topics/autodevops/index.md) or deploy your own web apps. | [stable/nginx-ingress](https://github.com/helm/charts/tree/master/stable/nginx-ingress) |
 | [Cert-Manager](https://docs.cert-manager.io/en/latest/) | 11.6+ | Cert-Manager is a native Kubernetes certificate management controller that helps with issuing certificates. Installing Cert-Manager on your cluster will issue a certificate by [Let's Encrypt](https://letsencrypt.org/) and ensure that certificates are valid and up-to-date. | [stable/cert-manager](https://github.com/helm/charts/tree/master/stable/cert-manager) |
+| [Prometheus](https://prometheus.io/docs/introduction/overview/) | 11.11+ | Prometheus is an open-source monitoring and alerting system useful to supervise your deployed applications. | [stable/prometheus](https://github.com/helm/charts/tree/master/stable/prometheus) |
 | [GitLab Runner](https://docs.gitlab.com/runner/) | 11.10+ | GitLab Runner is the open source project that is used to run your jobs and send the results back to GitLab. It is used in conjunction with [GitLab CI/CD](../../../ci/README.md), the open-source continuous integration service included with GitLab that coordinates the jobs. When installing the GitLab Runner via the applications, it will run in **privileged mode** by default. Make sure you read the [security implications](../../project/clusters/index.md#security-implications) before doing so. | [runner/gitlab-runner](https://gitlab.com/charts/gitlab-runner) |
 NOTE: **Note:**
@@ -38,8 +39,6 @@ applications in a group-level cluster is planned for future releases. For update
 - Support installing [JupyterHub in group-level
   clusters](https://gitlab.com/gitlab-org/gitlab-ce/issues/51989)
-- Support installing [Prometheus in group-level
-  clusters](https://gitlab.com/gitlab-org/gitlab-ce/issues/51963)
 ## RBAC compatibility

spec/presenters/group_clusterable_presenter_spec.rb

@@ -82,4 +82,10 @@ describe GroupClusterablePresenter do
     it { is_expected.to eq(group_cluster_path(group, cluster)) }
   end
+
+  describe '#clusters_path' do
+    subject { presenter.clusters_path }
+
+    it { is_expected.to eq(group_clusters_path(group)) }
+  end
 end

spec/presenters/project_clusterable_presenter_spec.rb

@@ -82,4 +82,10 @@ describe ProjectClusterablePresenter do
     it { is_expected.to eq(project_cluster_path(project, cluster)) }
   end
+
+  describe '#clusters_path' do
+    subject { presenter.clusters_path }
+
+    it { is_expected.to eq(project_clusters_path(project)) }
+  end
 end

spec/services/clusters/applications/create_service_spec.rb

@@ -151,8 +151,8 @@ describe Clusters::Applications::CreateService do
         'helm'       | :application_helm       | true | false
         'ingress'    | :application_ingress    | true | true
         'runner'     | :application_runner     | true | true
+        'prometheus' | :application_prometheus | true | true
         'jupyter'    | :application_jupyter    | false | true
-        'prometheus' | :application_prometheus | false | true
       end
       with_them do