Show basic system info on admin panel. Closes #18886

Gemfile

@@ -346,3 +346,7 @@ gem "paranoia", "~> 2.0"
 
 # Health check
 gem 'health_check', '~> 1.5.1'
+
+# System information
+gem 'vmstat', '~> 2.1.0'
+gem 'filesize', '~> 0.1.1'

Gemfile.lock

@@ -207,6 +207,7 @@ GEM
       multi_json
     ffaker (2.0.0)
     ffi (1.9.10)
+    filesize (0.1.1)
     flay (2.6.1)
       ruby_parser (~> 3.0)
       sexp_processor (~> 4.0)
@@ -780,6 +781,7 @@ GEM
       coercible (~> 1.0)
       descendants_tracker (~> 0.0, >= 0.0.3)
       equalizer (~> 0.0, >= 0.0.9)
+    vmstat (2.1.0)
     warden (1.2.6)
       rack (>= 1.0)
     web-console (2.3.0)
@@ -849,6 +851,7 @@ DEPENDENCIES
   email_spec (~> 1.6.0)
   factory_girl_rails (~> 4.6.0)
   ffaker (~> 2.0.0)
+  filesize (~> 0.1.1)
   flay
   flog
   fog-aws (~> 0.9)
@@ -984,6 +987,7 @@ DEPENDENCIES
   unicorn-worker-killer (~> 0.4.2)
   version_sorter (~> 2.0.0)
   virtus (~> 1.0.1)
+  vmstat (~> 2.1.0)
   web-console (~> 2.0)
   webmock (~> 1.21.0)
   wikicloth (= 0.8.1)

app/controllers/admin/system_info_controller.rb

+class Admin::SystemInfoController < Admin::ApplicationController
+  def show
+    system_info = Vmstat.snapshot
+    @load = system_info.load_average.collect { |v| v.round(2) }.join(', ')
+
+    @mem_used = Filesize.from("#{system_info.memory.active_bytes} B").to_s('GB')
+    @mem_total = Filesize.from("#{system_info.memory.total_bytes} B").to_s('GB')
+
+    @disk_used = Filesize.from("#{system_info.disks[0].used_bytes} B").to_s('GB')
+    @disk_total = Filesize.from("#{system_info.disks[0].total_bytes} B").to_s('GB')
+  end
+end

app/views/admin/background_jobs/_head.html.haml

 .nav-links.sub-nav
   %ul{ class: (container_class) }
+  = nav_link(controller: :system_info) do
+    = link_to admin_system_info_path, title: 'System Info' do
+      %span
+        System Info
     = nav_link(controller: :background_jobs) do
       = link_to admin_background_jobs_path, title: 'Background Jobs' do
         %span

app/views/admin/system_info/show.html.haml

+- @no_container = true
+- page_title "System Info"
+= render 'admin/background_jobs/head'
+
+%div{ class: (container_class) }
+  %p
+  .row
+    .col-sm-4
+      .light-well
+        %h4 CPU Load
+        .data
+          %h1= @load
+    .col-sm-4
+      .light-well
+        %h4 Memory
+        .data
+          %h1= "#{@mem_used} / #{@mem_total}"
+    .col-sm-4
+      .light-well
+        %h4 Disk
+        .data
+          %h1= "#{@disk_used} / #{@disk_total}"

config/routes.rb

@@ -280,6 +280,7 @@ Rails.application.routes.draw do
     resource :logs, only: [:show]
     resource :health_check, controller: 'health_check', only: [:show]
     resource :background_jobs, controller: 'background_jobs', only: [:show]
+    resource :system_info, controller: 'system_info', only: [:show]
 
     resources :namespaces, path: '/projects', constraints: { id: /[a-zA-Z.0-9_\-]+/ }, only: [] do
       root to: 'projects#index', as: :projects