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[Sam Clippinger <2120732@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

Every metadata request from a VM requires a three-step process to
succeed: Neutron metadata agent queries the Nova metadata service which
queries the database.  In our environment, some tools (especially a
specific AV product) query nearly every metadata endpoint every few
seconds.  Our AV vendor refuses to fix (or even acknowledge) their bug
and the load created by thousands of VMs causes our Nova infrastructure
to buckle under the strain.

Adding caching to the Neutron metadata agent fixes the problem.  We only
cache immutable data, such as the instance UUID, the userdata, the SSH
key, etc.  Values that may change over time are not cached, such as the
IP address.

The old bug #1235351 feels similar to this enhancement, except that
request was to cache all data for a short time rather than selectively
caching some endpoints.

** Affects: neutron
     Importance: Undecided
         Status: In Progress


** Tags: rfe

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https://bugs.launchpad.net/bugs/2120732

Title:
  [RFE] Add metadata caching for immutable values

Status in neutron:
  In Progress

Bug description:
  Every metadata request from a VM requires a three-step process to
  succeed: Neutron metadata agent queries the Nova metadata service
  which queries the database.  In our environment, some tools
  (especially a specific AV product) query nearly every metadata
  endpoint every few seconds.  Our AV vendor refuses to fix (or even
  acknowledge) their bug and the load created by thousands of VMs causes
  our Nova infrastructure to buckle under the strain.

  Adding caching to the Neutron metadata agent fixes the problem.  We
  only cache immutable data, such as the instance UUID, the userdata,
  the SSH key, etc.  Values that may change over time are not cached,
  such as the IP address.

  The old bug #1235351 feels similar to this enhancement, except that
  request was to cache all data for a short time rather than selectively
  caching some endpoints.

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