Dashboard memory warning

app/models/admin_dashboard_data.rb

@@ -1,3 +1,5 @@
+require_dependency 'mem_info'
+
 class AdminDashboardData
 
   REPORTS = ['visits', 'signups', 'topics', 'posts', 'flags', 'users_by_trust_level', 'likes', 'emails']
@@ -9,7 +11,7 @@ class AdminDashboardData
   def as_json
     @json ||= {
       reports: REPORTS.map { |type| Report.find(type) },
-      problems: [rails_env_check, host_names_check, gc_checks, sidekiq_check || clockwork_check].compact
+      problems: [rails_env_check, host_names_check, gc_checks, sidekiq_check || clockwork_check, ram_check].compact
     }.merge(
       SiteSetting.version_checks? ? {version_check: DiscourseUpdates.check_version} : {}
     )
@@ -35,4 +37,8 @@ class AdminDashboardData
   def clockwork_check
     I18n.t('dashboard.clockwork_warning') unless Jobs::ClockworkHeartbeat.is_clockwork_running?
   end
+
+  def ram_check
+    I18n.t('dashboard.memory_warning') if MemInfo.new.mem_total and MemInfo.new.mem_total < 1_000_000
+  end
 end

config/locales/server.en.yml

@@ -286,6 +286,7 @@ en:
     gc_warning: 'Your server is using default ruby garbage collection parameters, which will not give you the best performance. Read this topic on performance tuning: <a href="http://meta.discourse.org/t/tuning-ruby-and-rails-for-discourse/4126">Tuning Ruby and Rails for Discourse</a>.'
     clockwork_warning: 'Clockwork is not running. Ensure that a clockwork process is always running so that important jobs can be scheduled. <a href="https://github.com/tomykaira/clockwork">Learn about clockwork here</a>.'
     sidekiq_warning: 'Sidekiq is not running. Many tasks, like sending emails, are executed asynchronously by sidekiq. Please ensure at least one sidekiq process is running. <a href="https://github.com/mperham/sidekiq">Learn about Sidekiq here</a>.'
+    memory_warning: 'Your server is running with less than 1 GB of total memory. At least 1 GB of memory is recommended.'
 
   site_settings:
     default_locale: "The default language of this Discourse instance (ISO 639-1 Code)"

lib/mem_info.rb

@@ -0,0 +1,15 @@
+class MemInfo
+
+  # Total memory in kb. Only works on systems with /proc/meminfo.
+  # Returns nil if it cannot be determined.
+  def mem_total
+    @mem_total ||= begin
+      if s = `grep MemTotal /proc/meminfo`
+        /(\d+)/.match(s)[0].try(:to_i)
+      else
+        nil
+      end
+    end
+  end
+
+end

spec/models/admin_dashboard_data_spec.rb

@@ -102,4 +102,23 @@ describe AdminDashboardData do
     end
   end
 
+  describe 'ram_check' do
+    subject { AdminDashboardData.new.ram_check }
+
+    it 'returns nil when total ram is 1 GB' do
+      MemInfo.any_instance.stubs(:mem_total).returns(1025272)
+      subject.should be_nil
+    end
+
+    it 'returns nil when total ram cannot be determined' do
+      MemInfo.any_instance.stubs(:mem_total).returns(nil)
+      subject.should be_nil
+    end
+
+    it 'returns a string when total ram is less than 1 GB' do
+      MemInfo.any_instance.stubs(:mem_total).returns(512636)
+      subject.should_not be_nil
+    end
+  end
+
 end