From 0a1c2825fe688454871dbe5f73f8f27cdfc3e5a2 Mon Sep 17 00:00:00 2001 From: Balazs Gibizer Date: Thu, 2 May 2024 12:38:21 +0200 Subject: [PATCH] Document scaling out with new NodeSet This method of scaling out is needed to support heterogeneous node configuration. But it has some important quirks due to the global ssh-known-hosts service. --- docs/assemblies/scaling.adoc | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/docs/assemblies/scaling.adoc b/docs/assemblies/scaling.adoc index bf834c6d6..ae9e55dcc 100644 --- a/docs/assemblies/scaling.adoc +++ b/docs/assemblies/scaling.adoc @@ -94,6 +94,26 @@ $ oc rsh openstackclient openstack hypervisor list +--------------------------------------+-------------------------------------+-----------------+-----------------+-------+ ---- +== Scaling Out with different configuration + +If the deployment needs to be scaled out to nodes that require different +configuration (e.g. different kernel args, network config, or openstack config) +compared to the configuration in the current `OpenStackDataPlaneNodeSet` +then the new nodes cannot be added to the existing `OpenStackDataPlaneNodeSet` +but a new `OpenStackDataPlaneNodeSet` needs to be created that contains the +new nodes and the new configuration for those nodes. Then a new +`OpenStackDataPlaneDeployment` needs to be created that points to *both the +existing and the new `OpenStackDataPlaneNodeSets`* to trigger the scale out. + +WARNING: The existing `OpenStackDataPlaneNodeSet` has the `ssh-known-hosts` +service. That service is global for the whole deployment so it should not be +listed on the new `OpenStackDataPlaneNodeSet`. + +WARNING: If only the new `OpenStackDataPlaneNodeSet` is included into the new +`OpenStackDataPlaneDeployment` then the scale out seems to succeed but will +be incomplete causing that VM move operations will fail between nodes +in the different `OpenStackDataPlaneNodeSets`. + == Scaling In The procedure for removing edpm nodes from dataplane involves some manual cleanup steps @@ -200,3 +220,13 @@ compute-01 provisioned openstack-edpm true 2d21h compute-02 provisioned openstack-edpm true 2d21h compute-03 deprovisioning false 43h ---- + +== Scaling In by removing a NodeSet + +If the scale in would remove the last node from a `OpenStackDataPlaneNodeSet` +then the `OpenStackDataPlaneNodeSet` resource should deleted as well. If this +was the one that listed the `ssh-known-hosts` service then that service needs +to be added to exactly one of the remaining `OpenStackDataPlaneNodeSets`. To +remove the ssh host keys of the removed nodes from the remaining nodes a new +`OpenStackDataPlaneDeployment` needs to be created that points to all the +remaining `OpenStackDataPlaneNodeSets`.