openstack
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congress
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Add reactive enforcement example in doc 

In RST document congress/doc/source/enforcement.rst.

Add reactive enforcement example that can be executed
in console directly in 'Manual Reactive Enforcement'
section, and fix minor format issue.

Change-Id: I5a0d1cd39445b5dcbfa1448fd35558b913a71a6b
This commit is contained in:
Rui Chen 2015-10-28 10:24:03 +08:00
parent 2a0453ceb8
commit 84cfbdcb55
1 changed files with 6 additions and 4 deletions
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10
doc/source/enforcement.rst
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@ -331,7 +331,9 @@ that no server should have an ACTIVE status. The policy we write tells Congress
how to react when this policy is violated: it says to ask Nova to execute ``pause()``
every time it sees a server with ACTIVE status::
execute[nova:servers.pause(x)] :- nova:servers(id=x, status="ACTIVE")
$ openstack congress policy create reactive
$ openstack congress policy rule create reactive
'execute[nova:servers.pause(x)] :- nova:servers(id=x, status="ACTIVE")'
The way this works is that everytime Congress gets new data about the state of the cloud,
it figures out whether that new data causes any new rows to be added to the
@ -350,14 +352,14 @@ for the sake of pedagogy)::
Congress will then ask Nova to execute the following commands::
servers.pause("66dafde0-a49c-11e3-be40-425861b86ab6")
servers.pause("73e31d4c-a49c-11e3-be40-425861b86ab6")
nova:servers.pause("66dafde0-a49c-11e3-be40-425861b86ab6")
nova:servers.pause("73e31d4c-a49c-11e3-be40-425861b86ab6")
Congress will not wait for a response from Nova. Nor will it change the status of the two servers that it
asked Nova to pause in its ``nova:servers`` table. Congress will simply execute the pause() actions and
wait for new data to arrive, just like always.
Eventually Nova executes the pause() requests, the status of
those servers change, and Congress receives another data update.
those servers change, and Congress receives another data update::
nova:servers(id="66dafde0-a49c-11e3-be40-425861b86ab6", status="PAUSED")
nova:servers(id="73e31d4c-a49c-11e3-be40-425861b86ab6", status="PAUSED")