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Just a few wording and consistency improvements.
Signed-off-by: Niklas Hambuechen <niklash@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

The example filter did not actually do what was written in its description.

For `reason` predicates, the spec says

    "This predicate is true, if one of the entries of one of the opcodes
    in this job satisfies the expression."

The existing

    ["reason", ["!", ["=~", "reason", "maintenance pink bunny"]]]

would therefore match on pretty much all jobs submitted, as even
jobs with `--reason="maintenance pink bunny"` have other reason trail
entries that are not "maintenance pink bunny", and one such entry
suffices to satisfy the expression. Consequenlty, the given example
would in practice pause all new jobs.

The correct way to do this is a filter chain:

    prio 0  ["reason", ["=~", "reason", "maintenance pink bunny"]]  PASS
    prio 1  ["jobid", [">", "id", "watermark"]]                     PAUSE
Signed-off-by: Niklas Hambuechen <niklash@google.com>
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

This makes copy-pasting them into `gnt-filter`/curl easier since
JSON requires double quotes.

Admittedly, these were originally thought of as Python dicts so
the single quotes were fine, but in practice these examples are used
more often where JSON is required.
Signed-off-by: Niklas Hambuechen <niklash@google.com>
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

This makes the distinction between predicates *matching* and filter
rules *applying*.
Signed-off-by: Niklas Hambuechen <niklash@google.com>
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

Signed-off-by: Niklas Hambuechen <niklash@google.com>
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

In some cases, using the whole filter infra structure is quite
heavy for a simple rate limiting. Therefore, we will also add
a lightweight rate limiting via the reason trail.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

A feature often requested for the job queue is to limit certain
types of jobs. As the job filtering framework is the natural place
to host such a feature, explicitly describe rate limiting as one
of the supported actions.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

This is a design document detailing the semantics of the
fine-grained control of jobs in Ganeti.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>