hroller - Cluster rolling maintenance scheduler for Ganeti
hroller {backend options...} [algorithm options...] [reporting options...]
hroller –version
Backend options:
{ -m cluster | -L[ path ] | -t data-file | -I path }
Algorithm options:
[ -G *name* ]
[ -O *name...* ]
Reporting options:
[ -v... | -q ] [ -S *file* ]
hroller is a cluster maintenance reboot scheduler. It can calculate which set of nodes can be rebooted at the same time while avoiding having both primary and secondary nodes being rebooted at the same time.
For backends that support identifying the master node (currenlty RAPI and LUXI), the master node is scheduled as the last node in the last reboot group.
hroller will view the nodes as vertices of an undirected graph, connecting by instances which have both a primary and a secondary node. It will then color the graph using a few different heuristics, and return the minimum-size color set found. Node with the same color don’t share an edge, and as such don’t have an instance with both primary and secondary node on them, so they are safe to be rebooted concurrently.
Currently only standard htools options are supported. For a description of them check htools(1) and hbal(1).
Offline nodes should be ignored.
If instances are online the tool should refuse to do offline rolling maintenances, unless explicitly requested.
End-to-end shelltests should be provided.
Online rolling maintenances (where instance need not be shut down, but are migrated from node to node) are not supported yet. Hroller by design should support them both with and without secondary node replacement.
With the default options, the program shows one reboot group per line as a comma-separated list.
$ hroller -L
'Node Reboot Groups'
node1.example.com,node3.example.com,node5.example.com
node8.example.com,node6.example.com,node2.example.com
node7.example.com,node4.example.com