Detect new Amazon hypervisor used by the C5 instances

Signed-off-by: Tim Smith <tsmith@chef.io>

1 files changed, 37 insertions, 16 deletions

diff --git a/lib/ohai/plugins/ec2.rb b/lib/ohai/plugins/ec2.rb
index 1a3598d8..fdf0084a 100644
--- a/lib/ohai/plugins/ec2.rb
+++ b/lib/ohai/plugins/ec2.rb
@@ -21,7 +21,8 @@
 # How we detect EC2 from easiest to hardest & least reliable
 # 1. Ohai ec2 hint exists. This always works
 # 2. Xen hypervisor UUID starts with 'ec2'. This catches Linux HVM & paravirt instances
-# 3. DMI data mentions amazon. This catches HVM instances in a VPC
+# 3. DMI bios version data mentions amazon. This catches HVM instances in a VPC on the Xen based hypervisor
+# 3. DMI bios vendor data mentions amazon. This catches HVM instances in a VPC on the non-Xen based hypervisor
 # 4. Kernel data mentioned Amazon. This catches Windows HVM & paravirt instances
 
 Ohai.plugin(:EC2) do
@@ -33,32 +34,43 @@ Ohai.plugin(:EC2) do
   include Ohai::Mixin::HttpHelper
 
   provides "ec2"
-  depends "dmi"
 
-  # look for amazon string in dmi bios data
+  # look for amazon string in dmi vendor bios data within the sys tree.
+  # this works even if the system lacks dmidecode use by the Dmi plugin
+  # this gets us detection of new Xen-less HVM instances that are within a VPC
+  # @return [Boolean] do we have Amazon DMI data?
+  def has_ec2_amazon_dmi?
+    # detect a version of '4.2.amazon'
+    if file_val_if_exists("/sys/class/dmi/id/bios_vendor") =~ /Amazon/
+      Ohai::Log.debug("Plugin EC2: has_ec2_amazon_dmi? == true")
+      true
+    else
+      Ohai::Log.debug("Plugin EC2: has_ec2_amazon_dmi? == false")
+      false
+    end
+  end
+
+  # look for amazon string in dmi bios version data within the sys tree.
+  # this works even if the system lacks dmidecode use by the Dmi plugin
   # this gets us detection of HVM instances that are within a VPC
   # @return [Boolean] do we have Amazon DMI data?
-  def has_ec2_dmi?
+  def has_ec2_xen_dmi?
     # detect a version of '4.2.amazon'
-    if get_attribute(:dmi, :bios, :all_records, 0, :Version) =~ /amazon/
-      Ohai::Log.debug("Plugin EC2: has_ec2_dmi? == true")
+    if file_val_if_exists("/sys/class/dmi/id/bios_version") =~ /amazon/
+      Ohai::Log.debug("Plugin EC2: has_ec2_xen_dmi? == true")
       true
     else
-      Ohai::Log.debug("Plugin EC2: has_ec2_dmi? == false")
+      Ohai::Log.debug("Plugin EC2: has_ec2_xen_dmi? == false")
       false
     end
   end
 
-  # looks for a xen UUID that starts with ec2
-  # uses the sys tree on Linux and a WMI query on windows
-  # this gets us detection of HVM and Paravirt hosts
+  # looks for a xen UUID that starts with ec2 from within the Linux sys tree
   # @return [Boolean] do we have a Xen UUID or not?
   def has_ec2_xen_uuid?
-    if ::File.exist?("/sys/hypervisor/uuid")
-      if ::File.read("/sys/hypervisor/uuid") =~ /^ec2/
-        Ohai::Log.debug("Plugin EC2: has_ec2_xen_uuid? == true")
-        return true
-      end
+    if file_val_if_exists("/sys/hypervisor/uuid") =~ /^ec2/
+      Ohai::Log.debug("Plugin EC2: has_ec2_xen_uuid? == true")
+      return true
     end
     Ohai::Log.debug("Plugin EC2: has_ec2_xen_uuid? == false")
     false
@@ -82,13 +94,22 @@ Ohai.plugin(:EC2) do
     end
   end
 
+  # return the contents of a file if the file exists
+  # @param path[String] abs path to the file
+  # @return [String] contents of the file if it exists
+  def file_val_if_exists(path)
+    if ::File.exist?(path)
+      ::File.read(path)
+    end
+  end
+
   # a single check that combines all the various detection methods for EC2
   # @return [Boolean] Does the system appear to be on EC2
   def looks_like_ec2?
     return true if hint?("ec2")
 
     # Even if it looks like EC2 try to connect first
-    if has_ec2_xen_uuid? || has_ec2_dmi? || has_ec2_identifying_number?
+    if has_ec2_xen_uuid? || has_ec2_amazon_dmi? || has_ec2_xen_dmi? || has_ec2_identifying_number?
       return true if can_socket_connect?(Ohai::Mixin::Ec2Metadata::EC2_METADATA_ADDR, 80)
     end
   end