gnt-filter

Name

gnt-filter - Ganeti job filter rule administration

Synopsis

gnt-filter {command} [options...] [arguments...]

DESCRIPTION

The gnt-filter command is used for managing job filter rules in the Ganeti system. Filter rules are used by the Ganeti job scheduler to determine which jobs should be accepted, rejected, paused or rate-limited.

Filter rules consist of the following:

  • A UUID, used to refer to existing filters.

  • A watermark. This is the highest job id ever used, as valid in the moment when the filter was added or replaced.

  • A priority. This is a non-negative integer. Filters are processed in order of increasing priority. While there is a well-defined order in which rules of the same priority are evaluated (increasing watermark, then the UUID, are taken as tie breakers), it is not recommended to have rules of the same priority that overlap and have different actions associated.

  • A list of predicates to be matched against the job.

    A predicate is a list, with the first element being the name of the predicate and the rest being parameters suitable for that predicate. Most predicates take a single parameter, which is a boolean expression formulated in the of the Ganeti query language. The currently supported predicate names are:

    • jobid. Only parameter is a boolean expression. For this expression, there is only one field available, id, which represents the id the job to be filtered. In all value positions, the string watermark is replaced by the value of the watermark of the filter rule.
    • opcode. Only parameter is a boolean expression. For this expression, OP_ID and all other fields present in the opcode are available. This predicate will hold true, if the expression is true for at least one opcode in the job.
    • reason. Only parameter is a boolean expression. For this expression, the three fields source, reason, timestamp of reason trail entries are available. This predicate is true, if one of the entries of one of the opcodes in this job satisfies the expression.

  • An action. One of:

    • ACCEPT. The job will be accepted; no further filter rules are applied.
    • PAUSE. The job will be accepted to the queue and remain there; however, it is not executed. Has no effect if the job is already running.
    • REJECT. The job is rejected. If it is already in the queue, it will be cancelled.
    • CONTINUE. The filtering continues processing with the next rule. Such a rule will never have any direct or indirect effect, but it can serve as documentation for a “normally present, but currently disabled” rule.
    • RATE_LIMIT n, where n is a positive integer. The job will be held in the queue while n or more jobs where this rule applies are running. Jobs already running when this rule is added are not changed. Logically, this rule is applied job by job sequentially, so that the number of jobs where this rule applies is limited to n once the jobs running at rule addition have finished.

  • A reason trail, in the same format as reason trails for job opcodes (see the --reason option in ganeti(7)). This allows to find out which maintenance (or other reason) caused the addition of this filter rule.

COMMANDS

ADD

add
[–priority=*priority*]
[–predicates=*predicates*]
[–action=*action*]

Creates a new filter rule. A UUID is automatically assigned.

The --priority option sets the priority of the filter. It is a non-negative integer. Default: 0 (the highest possible priority).

The --predicates option sets the predicates of the filter. It is a list of predicates in the format described in the DESCRIPTION above. Default: [] (no predicate, filter always matches).

The --action option sets the action of the filter. It is one of the strings ACCEPT, PAUSE, REJECT, CONTINUE, or RATE_LIMIT n (see the DESCRIPTION above). Default: CONTINUE.

See ganeti(7) for a description of --reason and other common options.

REPLACE

replace
[–priority=*priority*]
[–predicates=*predicates*]
[–action=*action*]
[–reason=*reason*]
{filter-uuid}

Replaces a filter rule, or creates one if it doesn’t already exist.

Accepts all options described above in ADD.

When being replaced, the filter will be assigned an updated watermark.

See ganeti(7) for a description of --reason and other common options.

DELETE

delete {filter-uuid}

Deletes the indicated filter rule.

LIST

list [–no-headers] [–separator=*separator*] [-v]
[-o [+]field,...] [filter-uuid...]

Lists all existing filters in the cluster. If no filter UUIDs are given, then all filters are included. Otherwise, only the given filters will be listed.

The --no-headers option will skip the initial header line. The --separator option takes an argument which denotes what will be used between the output fields. Both these options are to help scripting.

The -v option activates verbose mode, which changes the display of special field states (see ganeti(7)).

The -o option takes a comma-separated list of output fields. If the value of the option starts with the character +, the new fields will be added to the default list. This allows to quickly see the default list plus a few other fields, instead of retyping the entire list of fields.

The available fields and their meaning are:

action
Action
predicates
Predicates
priority
Priority
reason_trail
Reason trail
uuid
Network UUID
watermark
Watermark

LIST-FIELDS

list-fields [field...]

List available fields for filters.

INFO

info [filter-uuid...]

Displays information about a given filter.

EXAMPLES

Draining the queue.

gnt-filter add '--predicates=[["jobid", [">", "id", "watermark"]]]' --action=REJECT

Soft draining could be achieved by replacing REJECT by PAUSE in the above example.

Pausing all new jobs not belonging to a specific maintenance.

gnt-filter add --priority=0 '--predicates=[["reason", ["=~", "reason", "maintenance pink bunny"]]]' --action=ACCEPT
gnt-filter add --priority=1 '--predicates=[["jobid", [">", "id", "watermark"]]]' --action=PAUSE

Cancelling all queued instance creations and disallowing new such jobs.

gnt-filter add '--predicates=[["opcode", ["=", "OP_ID", "OP_INSTANCE_CREATE"]]]' --action=REJECT

Limiting the number of simultaneous instance disk replacements to 10 in order to throttle replication traffic.

gnt-filter add '--predicates=[["opcode", ["=", "OP_ID", "OP_INSTANCE_REPLACE_DISKS"]]]' '--action=RATE_LIMIT 10'