krb5 commit [krb5-1.17]: Document necessary delay in master key rolllover

[Greg Hudson]

https://github.com/krb5/krb5/commit/91f331c507f6d36906b8432485b9b639c31ebff2
commit 91f331c507f6d36906b8432485b9b639c31ebff2
Author: Greg Hudson <ghudson at mit.edu>
Date:   Mon Nov 26 13:37:46 2018 -0500

    Document necessary delay in master key rolllover
    
    During master key rollover, if the old master key is purged
    immediately after updating principal encryption, running processes may
    not successfully update their in-memory copies of the master key.
    Document that the administrator should delay purging the master key
    until after propagation and some daemon activity.
    
    (cherry picked from commit 24425b730161c3d27d86a7ae0caa2305f70167f6)
    
    ticket: 8744
    version_fixed: 1.17

 doc/admin/database.rst |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/doc/admin/database.rst b/doc/admin/database.rst
index 14c145b..2b02af3 100644
--- a/doc/admin/database.rst
+++ b/doc/admin/database.rst
@@ -535,6 +535,10 @@ availability.  To roll over the master key, follow these steps:
    use unlocked iteration; this variant will take longer, but will
    keep the database available to the KDC and kadmind while it runs.
 
+#. Wait until the above changes have propagated to all replica KDCs
+   and until all running KDC and kadmind processes have serviced
+   requests using updated principal entries.
+
 #. On the master KDC, run ``kdb5_util purge_mkeys`` to clean up the
    old master key.