Merge branch '21378-error-500-after-8-11-update-on-system-infos-page' into 'master'

Handle unavailable system info

## What does this MR do?

Handle the case where we can't get system info without blowing up. As this is the first tab in the monitoring section, it's difficult to get to the other tabs if this page throws a 500. Also be more specific about the info we want, so we don't fail on something we don't care about (like `/proc/net/dev`).

## Why was this MR needed?

grsecurity can prevent users from reading `/proc`, which is what Vmstat uses to find CPU and memory info.

## What are the relevant issue numbers?

Closes #21378.

See merge request !5989

6 files changed, 60 insertions, 16 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 4522b268592..e54f293e5ff 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -15,6 +15,9 @@ v 8.12.0 (unreleased)
   - Use the default branch for displaying the project icon instead of master !5792 (Hannes Rosenögger)
   - Adds response mime type to transaction metric action when it's not HTML
 
+v 8.11.3 (unreleased)
+  - Allow system info page to handle case where info is unavailable
+
 v 8.11.2 (unreleased)
   - Show "Create Merge Request" widget for push events to fork projects on the source project
 
diff --git a/Gemfile b/Gemfile
index 68547b6fac8..194379dd687 100644
--- a/Gemfile
+++ b/Gemfile
@@ -349,5 +349,5 @@ gem 'paranoia', '~> 2.0'
 gem 'health_check', '~> 2.1.0'
 
 # System information
-gem 'vmstat', '~> 2.1.1'
+gem 'vmstat', '~> 2.2'
 gem 'sys-filesystem', '~> 1.1.6'
diff --git a/Gemfile.lock b/Gemfile.lock
index 5511d718938..0c28975060c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -772,7 +772,7 @@ GEM
       coercible (~> 1.0)
       descendants_tracker (~> 0.0, >= 0.0.3)
       equalizer (~> 0.0, >= 0.0.9)
-    vmstat (2.1.1)
+    vmstat (2.2.0)
     warden (1.2.6)
       rack (>= 1.0)
     web-console (2.3.0)
@@ -980,7 +980,7 @@ DEPENDENCIES
   unicorn-worker-killer (~> 0.4.2)
   version_sorter (~> 2.1.0)
   virtus (~> 1.0.1)
-  vmstat (~> 2.1.1)
+  vmstat (~> 2.2)
   web-console (~> 2.0)
   webmock (~> 1.21.0)
   wikicloth (= 0.8.1)
diff --git a/app/controllers/admin/system_info_controller.rb b/app/controllers/admin/system_info_controller.rb
index e4c73008826..ca04a17caa1 100644
--- a/app/controllers/admin/system_info_controller.rb
+++ b/app/controllers/admin/system_info_controller.rb
@@ -29,7 +29,8 @@ class Admin::SystemInfoController < Admin::ApplicationController
   ]
 
   def show
-    system_info = Vmstat.snapshot
+    @cpus = Vmstat.cpu rescue nil
+    @memory = Vmstat.memory rescue nil
     mounts = Sys::Filesystem.mounts
 
     @disks = []
@@ -50,10 +51,5 @@ class Admin::SystemInfoController < Admin::ApplicationController
       rescue Sys::Filesystem::Error
       end
     end
-
-    @cpus = system_info.cpus.length
-
-    @mem_used = system_info.memory.active_bytes
-    @mem_total = system_info.memory.total_bytes
   end
 end
diff --git a/app/views/admin/system_info/show.html.haml b/app/views/admin/system_info/show.html.haml
index 6956e5ab795..bfc6142067a 100644
--- a/app/views/admin/system_info/show.html.haml
+++ b/app/views/admin/system_info/show.html.haml
@@ -9,12 +9,20 @@
       .light-well
         %h4 CPU
         .data
-          %h1= "#{@cpus} cores"
+          - if @cpus
+            %h1= "#{@cpus.length} cores"
+          - else
+            = icon('warning', class: 'text-warning')
+            Unable to collect CPU info
     .col-sm-4
       .light-well
         %h4 Memory
         .data
-          %h1= "#{number_to_human_size(@mem_used)} / #{number_to_human_size(@mem_total)}"
+          - if @memory
+            %h1= "#{number_to_human_size(@memory.active_bytes)} / #{number_to_human_size(@memory.total_bytes)}"
+          - else
+            = icon('warning', class: 'text-warning')
+            Unable to collect memory info
     .col-sm-4
       .light-well
         %h4 Disks
diff --git a/spec/features/admin/admin_system_info_spec.rb b/spec/features/admin/admin_system_info_spec.rb
index f4e5c26b519..1df972843e2 100644
--- a/spec/features/admin/admin_system_info_spec.rb
+++ b/spec/features/admin/admin_system_info_spec.rb
@@ -6,12 +6,49 @@ describe 'Admin System Info' do
   end
 
   describe 'GET /admin/system_info' do
-    it 'shows system info page' do
-      visit admin_system_info_path
+    let(:cpu) { double(:cpu, length: 2) }
+    let(:memory) { double(:memory, active_bytes: 4294967296, total_bytes: 17179869184) }
 
-      expect(page).to have_content 'CPU'
-      expect(page).to have_content 'Memory'
-      expect(page).to have_content 'Disks'
+    context 'when all info is available' do
+      before do
+        allow(Vmstat).to receive(:cpu).and_return(cpu)
+        allow(Vmstat).to receive(:memory).and_return(memory)
+        visit admin_system_info_path
+      end
+
+      it 'shows system info page' do
+        expect(page).to have_content 'CPU 2 cores'
+        expect(page).to have_content 'Memory 4 GB / 16 GB'
+        expect(page).to have_content 'Disks'
+      end
+    end
+
+    context 'when CPU info is not available' do
+      before do
+        allow(Vmstat).to receive(:cpu).and_raise(Errno::ENOENT)
+        allow(Vmstat).to receive(:memory).and_return(memory)
+        visit admin_system_info_path
+      end
+
+      it 'shows system info page with no CPU info' do
+        expect(page).to have_content 'CPU Unable to collect CPU info'
+        expect(page).to have_content 'Memory 4 GB / 16 GB'
+        expect(page).to have_content 'Disks'
+      end
+    end
+
+    context 'when memory info is not available' do
+      before do
+        allow(Vmstat).to receive(:cpu).and_return(cpu)
+        allow(Vmstat).to receive(:memory).and_raise(Errno::ENOENT)
+        visit admin_system_info_path
+      end
+
+      it 'shows system info page with no CPU info' do
+        expect(page).to have_content 'CPU 2 cores'
+        expect(page).to have_content 'Memory Unable to collect memory info'
+        expect(page).to have_content 'Disks'
+      end
     end
   end
 end