Additional resource required by "REPLACE" update policy

asked 2018-01-18 02:58:30 -0500

Leo999 gravatar image

User-data update in HOT template will trigger "REPLACE" when use "heat stack-update" to take change into use. "REPLACE" policy creates a new VM before delete the old one, so it requires double CPU cores to execute "REPLACE" update policy, if the VM uses other resource, eg cinder volume, vNIC, do these resource need double for the period new VM is created but before old VM is deleted?

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answered 2018-01-23 11:20:45 -0500

zaneb gravatar image

For the most part, no. Replacing one resource does not cause resources it depends on (e.g. Volumes or Ports) to also be replaced. (In fact, with the way Heat currently works, this would require time travel ;)

However, if you implicitly create ports as part of the server creation (e.g. by specifying networks to attach to without specifying explicit ports) then the new server will create its own ports. (This is probably what you want to happen anyway.)

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@zaneb, thanks for the explanation! I explicit attach the volume and ports to the VM, so it means no additional this part resource required, it matched my test result. :-)

Leo999 gravatar imageLeo999 ( 2018-01-23 23:14:06 -0500 )edit

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Asked: 2018-01-18 02:58:30 -0500

Seen: 192 times

Last updated: Jan 23 '18