harep - Ganeti auto-repair tool
harep [ [-L | --luxi ] = socket ] [ --job-delay = seconds ]
harep --version
Harep is the Ganeti auto-repair tool. It is able to detect that an instance is broken and to generate a sequence of jobs that will fix it, in accordance to the policies set by the administrator.
Harep is able to recognize what state an instance is in (healthy, suspended, needs repair, repair disallowed, pending repair, repair disallowed, repair failed) and to lead it through a sequence of steps that will bring the instance back to the healthy state. Therefore, harep is mainly meant to be run regularly and frequently using a cron job, so that is can actually follow the instance along all the process. At every run, harep will update the tags it adds to instances that describe its repair status, and will submit jobs that actually perform the required repair operations.
By default, harep only reports on the health status of instances, but doesn't perform any action, as they might be potentially dangerous. Therefore, harep will only touch instances that it has been explicitly authorized to work on.
The tags enabling harep, can be associated to single instances, or to a nodegroup or to the whole cluster, therefore affecting all the instances they contain. The possible tags share the common structure:
ganeti:watcher:autorepair:<type>where <type> can have the following values:
fix-storage: allow disk replacement or fix the backend without affecting the instance itself (broken DRBD secondary)migrate: allow instance migrationfailover: allow instance reboot on the secondaryreinstall: allow disks to be recreated and the instance to be reinstalledEach element in the list of tags, includes all the authorizations of the previous one, with fix-storage being the least powerful and reinstall being the most powerful.
In case multiple autorepair tags act on the same instance, only one can actually be active. The conflict is solved according to the following rules:
if multiple tags are in the same object, the least destructive takes precedence.
if the tags are across objects, the nearest tag wins.
Example: A cluster has instances I1 and I2, where I1 has the failover tag, and the cluster has both fix-storage and reinstall. The I1 instance will be allowed to failover, the I2 instance only to fix-storage.
Harep doesn't do any hardware failure detection on its own, it relies on nodes being marked as offline by the administrator.
Also harep currently works only for instances with the drbd and plain disk templates.
Both these issues will be addressed by a new maintenance daemon in future Ganeti versions, which will supersede harep.
The options that can be passed to the program are as follows:
collect data via Luxi, optionally using the given socket path.
insert this much delay before the execution of repair jobs to allow the tool to continue processing instances.
Report bugs to project website or contact the developers using the Ganeti mailing list.
Ganeti overview and specifications: ganeti(7) (general overview), ganeti-os-interface(7) (guest OS definitions), ganeti-extstorage-interface(7) (external storage providers).
Ganeti commands: gnt-cluster(8) (cluster-wide commands), gnt-job(8) (job-related commands), gnt-node(8) (node-related commands), gnt-instance(8) (instance commands), gnt-os(8) (guest OS commands), gnt-storage(8) (storage commands), gnt-group(8) (node group commands), gnt-backup(8) (instance import/export commands), gnt-debug(8) (debug commands).
Ganeti daemons: ganeti-watcher(8) (automatic instance restarter), ganeti-cleaner(8) (job queue cleaner), ganeti-noded(8) (node daemon), ganeti-masterd(8) (master daemon), ganeti-rapi(8) (remote API daemon).
Ganeti htools: htools(1) (generic binary), hbal(1) (cluster balancer), hspace(1) (capacity calculation), hail(1) (IAllocator plugin), hscan(1) (data gatherer from remote clusters), hinfo(1) (cluster information printer), mon-collector(7) (data collectors interface).
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