Merge branch '43532-error-on-admin-applications-prometheus-template' into 'master'

Resolve "Error 500 on route "/admin/application_settings/services/1882/edit" -> edit Prometheus Service Template"

Closes #43532

See merge request gitlab-org/gitlab-ce!17377

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

+%h4
+  = s_('PrometheusService|Auto configuration')
+
+- if service.manual_configuration?
+  .well
+    = s_('PrometheusService|To enable the installation of Prometheus on your clusters, deactivate the manual configuration below')
+- else
+  .container-fluid
+    .row
+      - if service.prometheus_installed?
+        .col-sm-2
+          .svg-container
+            = image_tag 'illustrations/monitoring/getting_started.svg'
+        .col-sm-10
+          %p.text-success.prepend-top-default
+            = s_('PrometheusService|Prometheus is being automatically managed on your clusters')
+          = link_to s_('PrometheusService|Manage clusters'), project_clusters_path(project), class: 'btn'
+      - else
+        .col-sm-2
+          = image_tag 'illustrations/monitoring/loading.svg'
+        .col-sm-10
+          %p.prepend-top-default
+            = s_('PrometheusService|Automatically deploy and configure Prometheus on your clusters to monitor your project’s environments')
+          = link_to s_('PrometheusService|Install Prometheus on clusters'), project_clusters_path(project), class: 'btn btn-success'
+
+%hr

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

-%h4
-  = s_('PrometheusService|Auto configuration')
-
-- if @service.manual_configuration?
-  .well
-    = s_('PrometheusService|To enable the installation of Prometheus on your clusters, deactivate the manual configuration below')
-- else
-  .container-fluid
-    .row
-      - if @service.prometheus_installed?
-        .col-sm-2
-          .svg-container
-            = image_tag 'illustrations/monitoring/getting_started.svg'
-        .col-sm-10
-          %p.text-success.prepend-top-default
-            = s_('PrometheusService|Prometheus is being automatically managed on your clusters')
-          = link_to s_('PrometheusService|Manage clusters'), project_clusters_path(@project), class: 'btn'
-      - else
-        .col-sm-2
-          = image_tag 'illustrations/monitoring/loading.svg'
-        .col-sm-10
-          %p.prepend-top-default
-            = s_('PrometheusService|Automatically deploy and configure Prometheus on your clusters to monitor your project’s environments')
-          = link_to s_('PrometheusService|Install Prometheus on clusters'), project_clusters_path(@project), class: 'btn btn-success'
-
-%hr
+- if @project
+  = render 'projects/services/prometheus/configuration_banner', project: @project, service: @service
 
 %h4.append-bottom-default
   = s_('PrometheusService|Manual configuration')

changelogs/unreleased/43532-error-on-admin-applications-prometheus-template.yml

+---
+title: Fixes Prometheus admin configuration page
+merge_request: 17377
+author:
+type: fixed

spec/features/admin/services/admin_activates_prometheus_spec.rb

+require 'spec_helper'
+
+describe 'Admin activates Prometheus' do
+  let(:admin) { create(:user, :admin) }
+
+  before do
+    sign_in(admin)
+
+    visit(admin_application_settings_services_path)
+
+    click_link('Prometheus')
+  end
+
+  it 'activates service' do
+    check('Active')
+    fill_in('API URL', with: 'http://prometheus.example.com')
+    click_button('Save')
+
+    expect(page).to have_content('Application settings saved successfully')
+  end
+end

spec/features/projects/services/user_activates_prometheus_spec.rb

+require 'spec_helper'
+
+describe 'User activates Prometheus' do
+  let(:project) { create(:project) }
+  let(:user) { create(:user) }
+
+  before do
+    project.add_master(user)
+    sign_in(user)
+
+    visit(project_settings_integrations_path(project))
+
+    click_link('Prometheus')
+  end
+
+  it 'activates service' do
+    check('Active')
+    fill_in('API URL', with: 'http://prometheus.example.com')
+    click_button('Save changes')
+
+    expect(page).to have_content('Prometheus activated.')
+  end
+end