Set kubelet eviction-hard based on total memory

lib/puppet/functions/five_percent_of_total_ram.rb

@@ -0,0 +1,16 @@
+Puppet::Functions.create_function(:five_percent_of_total_ram) do
+  dispatch :five_percent_of_total_ram do
+    param 'Integer', :total_bytes
+  end
+
+  def five_percent_of_total_ram(total_bytes)
+    five_percent = (total_bytes * 0.05 / 1024**2).round
+    default = 100
+
+    if five_percent < default
+      '100Mi'
+    else
+      five_percent.to_s + 'Mi'
+    end
+  end
+end

manifests/kubelet.pp

@@ -10,6 +10,8 @@
   String $role = 'worker',
   String $container_runtime = 'docker',
   String $kubelet_dir = '/var/lib/kubelet',
+  String $hard_eviction_memory_threshold =
+    five_percent_of_total_ram(dig44($facts, ['memory', 'system', 'total_bytes'], 1)),
   Optional[String] $network_plugin = undef,
   Integer $network_plugin_mtu = 1460,
   Boolean $allow_privileged = true,

spec/classes/kubelet_spec.rb

@@ -20,6 +20,7 @@
       should_not contain_file(service_file).with_content(/--network-plugin/)
       should contain_file(service_file).with_content(/--container-runtime=docker/)
       should contain_file(service_file).with_content(%r{--kubeconfig=/etc/kubernetes/kubeconfig-kubelet})
+      should contain_file(service_file).with_content(%r{--eviction-hard="memory.available<191Mi"})
     end
   end
 

spec/spec_helper.rb

@@ -5,5 +5,10 @@
     :path => '/bin:/sbin:/usr/bin:/usr/sbin:/opt/bin',
     :osfamily => 'RedHat',
     :kernelversion => '3.11.1',
+    :memory => {
+      :system => {
+        :total_bytes => 4_000_000_000,
+      }
+    }
   }
 end

templates/kubelet.service.erb

@@ -103,6 +103,7 @@ ExecStart=<%= scope['kubernetes::_dest_dir'] %>/kubelet \
   "--tls-cert-file=<%= @cert_file %>" \
   "--tls-private-key-file=<%= @key_file %>" \
 <% end -%>
+  --eviction-hard="memory.available<<%= @hard_eviction_memory_threshold %>" \
   --logtostderr=true
 
 Restart=on-failure