Do not override #editable? in PrometheusService

- Also add specs to ensure that #fields method always returns the
fields, even when there is a cluster present with Prometheus installed.

- This is being done so that the Prometheus manual configuration is
editable even when there is a Prometheus managed app installed on a
cluster.

app/models/project_services/prometheus_service.rb

@@ -36,10 +36,6 @@ class PrometheusService < MonitoringService
     false
   end
 
-  def editable?
-    manual_configuration? || !prometheus_available?
-  end
-
   def title
     'Prometheus'
   end
@@ -53,8 +49,6 @@ class PrometheusService < MonitoringService
   end
 
   def fields
-    return [] unless editable?
-
     [
       {
         type: 'checkbox',

app/views/projects/services/_form.html.haml

@@ -12,11 +12,10 @@
   .col-lg-9
     = form_for(@service, as: :service, url: scoped_integration_path(@service), method: :put, html: { class: 'gl-show-field-errors integration-settings-form js-integration-settings-form', data: { 'can-test' => @service.can_test?, 'test-url' => test_project_service_path(@project, @service) } }) do |form|
       = render 'shared/service_settings', form: form, service: @service
-      - if @service.editable?
-        .footer-block.row-content-block
-          = service_save_button(@service)
-           
-          = link_to _('Cancel'), project_settings_integrations_path(@project), class: 'btn btn-cancel'
+      .footer-block.row-content-block
+        = service_save_button(@service)
+         
+        = link_to _('Cancel'), project_settings_integrations_path(@project), class: 'btn btn-cancel'
 
 - if lookup_context.template_exists?('show', "projects/services/#{@service.to_param}", true)
   %hr

app/views/projects/services/prometheus/_help.html.haml

@@ -3,7 +3,5 @@
 
 %h4.append-bottom-default
   = s_('PrometheusService|Manual configuration')
-
-- unless @service.editable?
-  .info-well
-    = s_('PrometheusService|To enable manual configuration, uninstall Prometheus from your clusters')
+%p
+  = s_('PrometheusService|Select the Active checkbox to override the Auto Configuration with custom settings. If unchecked, Auto Configuration settings are used.')

app/views/projects/settings/operations/_prometheus.html.haml

@@ -13,7 +13,5 @@
 
     %b.append-bottom-default
       = s_('PrometheusService|Manual configuration')
-
-    - unless service.editable?
-      .info-well
-        = s_('PrometheusService|To enable manual configuration, uninstall Prometheus from your clusters')
+    %p
+      = s_('PrometheusService|Select the Active checkbox to override the Auto Configuration with custom settings. If unchecked, Auto Configuration settings are used.')

changelogs/unreleased/207233-k8s-cluster-blocks-project-manual-prometheus-configuration.yml

+---
+title: Make manual prometheus configuration section always editable
+merge_request: 29209
+author:
+type: changed

locale/gitlab.pot

@@ -16342,13 +16342,13 @@ msgstr ""
 msgid "PrometheusService|Prometheus is being automatically managed on your clusters"
 msgstr ""
 
-msgid "PrometheusService|These metrics will only be monitored after your first deployment to an environment"
+msgid "PrometheusService|Select the Active checkbox to override the Auto Configuration with custom settings. If unchecked, Auto Configuration settings are used."
 msgstr ""
 
-msgid "PrometheusService|Time-series monitoring service"
+msgid "PrometheusService|These metrics will only be monitored after your first deployment to an environment"
 msgstr ""
 
-msgid "PrometheusService|To enable manual configuration, uninstall Prometheus from your clusters"
+msgid "PrometheusService|Time-series monitoring service"
 msgstr ""
 
 msgid "PrometheusService|To enable the installation of Prometheus on your clusters, deactivate the manual configuration below"

spec/lib/gitlab/prometheus/adapter_spec.rb

@@ -19,6 +19,14 @@ describe Gitlab::Prometheus::Adapter do
       it 'return prometheus service as prometheus adapter' do
         expect(subject.prometheus_adapter).to eq(prometheus_service)
       end
+
+      context 'with cluster with prometheus available' do
+        let!(:prometheus) { create(:clusters_applications_prometheus, :installed, cluster: cluster) }
+
+        it 'returns prometheus service' do
+          expect(subject.prometheus_adapter).to eq(prometheus_service)
+        end
+      end
     end
 
     context "prometheus service can't execute queries" do

spec/models/project_services/prometheus_service_spec.rb

@@ -418,4 +418,48 @@ describe PrometheusService, :use_clean_rails_memory_store_caching do
       end
     end
   end
+
+  describe '#editable?' do
+    it 'is editable' do
+      expect(service.editable?).to be(true)
+    end
+
+    context 'when cluster exists with prometheus installed' do
+      let(:cluster) { create(:cluster, projects: [project]) }
+
+      before do
+        service.update!(manual_configuration: false)
+
+        create(:clusters_applications_prometheus, :installed, cluster: cluster)
+      end
+
+      it 'remains editable' do
+        expect(service.editable?).to be(true)
+      end
+    end
+  end
+
+  describe '#fields' do
+    let(:expected_fields) do
+      [
+        {
+          type: 'checkbox',
+          name: 'manual_configuration',
+          title: s_('PrometheusService|Active'),
+          required: true
+        },
+        {
+          type: 'text',
+          name: 'api_url',
+          title: 'API URL',
+          placeholder: s_('PrometheusService|Prometheus API Base URL, like http://prometheus.example.com/'),
+          required: true
+        }
+      ]
+    end
+
+    it 'returns fields' do
+      expect(service.fields).to eq(expected_fields)
+    end
+  end
 end