Add exception to no-upcall note of cells doc
The cells v2 layout documentation clearly states that there are no upcalls from cells back to the central API services. This mislead me for sometime as I could not fathom how a compute node in a cell was supposed to report its resource info. It turns out nova looks up the placement service in the keystone catalogue and contacts it directly which to my mind is an upcall. I wonder if the author of the not felt that the placement service is not really part of nova? Change-Id: If14be8b182f0af4e4e6641046fec638c07e26546 Closes-Bug: #1742421
This commit is contained in:
parent
90a92d33ed
commit
30786b892e
|
@ -231,15 +231,16 @@ to distinguish its place and purpose from the per-cell conductor nodes.
|
|||
conductor -> mq2
|
||||
}
|
||||
|
||||
It is important to note that services in the lower cell boxes do not
|
||||
have the ability to call back to the API-layer services via RPC, nor
|
||||
do they have access to the API database for global visibility of
|
||||
resources across the cloud. This is intentional and provides security
|
||||
and failure domain isolation benefits, but also has impacts on some
|
||||
things that would otherwise require this any-to-any communication
|
||||
style. Check the release notes for the version of Nova you are using
|
||||
for the most up-to-date information about any caveats that may be
|
||||
present due to this limitation.
|
||||
It is important to note that services in the lower cell boxes only
|
||||
have the ability to call back to the placement API but cannot access
|
||||
any other API-layer services via RPC, nor do they have access to the
|
||||
API database for global visibility of resources across the cloud.
|
||||
This is intentional and provides security and failure domain
|
||||
isolation benefits, but also has impacts on some things that would
|
||||
otherwise require this any-to-any communication style. Check the
|
||||
release notes for the version of Nova you are using for the most
|
||||
up-to-date information about any caveats that may be present due to
|
||||
this limitation.
|
||||
|
||||
Caveats of a Multi-Cell deployment
|
||||
----------------------------------
|
||||
|
|
Loading…
Reference in New Issue