18562: Add upgrade note about new config key.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curii.com>

diff --git a/doc/admin/upgrading.html.textile.liquid b/doc/admin/upgrading.html.textile.liquid
index 411e2ea0ff3cf3d4d4b0e8bd1c7852b336f6ae58..2bd41829bea9ebb20fbd359a6cce5836a93177f8 100644 (file)
--- a/doc/admin/upgrading.html.textile.liquid
+++ b/doc/admin/upgrading.html.textile.liquid
@@ -39,6 +39,10 @@ h2(#main). development main (as of 2021-11-10)
 
 "previous: Upgrading from 2.3.0":#v2_3_0
 
+h3. Preemptible instance types are used automatically, if any are configured
+
+The default behavior for selecting "preemptible instances":{{site.baseurl}}/admin/spot-instances.html has changed. If your configuration lists any instance types with @Preemptible: true@, all child (non-top-level) containers will automatically be scheduled on preemptible instances. To avoid using preemptible instances except when explicitly requested by clients, add @AlwaysUsePreemptibleInstances: false@ in the @Containers@ config section. (Previously, preemptible instance types were never used unless the configuration specified @UsePreemptibleInstances: true@. That flag has been removed.)
+
 h3. Role groups are visible to all users by default
 
 The permission model has changed such that all role groups are visible to all active users. This enables users to share objects with groups they don't belong to. To preserve the previous behavior, where role groups are only visible to members and admins, add @RoleGroupsVisibleToAll: false@ to the @Users@ section of your configuration file.