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From John Rushford <>
Subject Host status metric change in ATS 8.1
Date Thu, 16 Apr 2020 21:07:54 GMT

With ATS 8.1 I would like find out if a change in the host status metric
from ATS 8.0 can be made.  Host status is new with 8.0 and I suspect not
many are using it yet so, we would like to make a change to the metric in

The host status metrics are used in ATS by parent selection and traffic_ctl
to report and determine if a parent is available for use.  A user may use
the 'traffic_ctl host' command to mark a parent as up or down for use by
parent selection and that hosts status is then kept in a metric.  For
example in ATS 8.0 a metric could be:

*host_status. 1.   *

the metric prefix "host_status" followed by a host name or IP and it's
current state:
 0 = unavailable
 1 = available.

In ATS 8.1 more features would be added to support health checking,
downtime, and more.  In order to serialize the state I've used this new
metric format:


This new format serializes the state of a host with reason codes and the
times that they were marked down and the state is loaded across restarts.
This format and the feature change is used in ATS 9.0 and was cherry-picked
into the new 8.1 branch.  Details regarding use of this feature are here:

I would like to see if the community is agreeable to this metric and
feature change from 8.0 to 8.1.

John Rushford

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