This commit adds support for limits and filters to the Prometheus Rules
API.
Limits:
It adds a number of limits to the Grafana flavour of the Prometheus Rules
API:
- `limit` limits the maximum number of Rule Groups returned
- `limit_rules` limits the maximum number of rules per Rule Group
- `limit_alerts` limits the maximum number of alerts per rule
It sorts Rule Groups and rules within Rule Groups such that data in the
response is stable across requests. It also returns summaries (totals)
for all Rule Groups, individual Rule Groups and rules.
Filters:
Alerts can be filtered by state with the `state` query string. An example
of an HTTP request asking for just firing alerts might be
`/api/prometheus/grafana/api/v1/rules?state=alerting`.
A request can filter by two or more states by adding additional `state`
query strings to the URL. For example `?state=alerting&state=normal`.
Like the alert list panel, the `firing`, `pending` and `normal` state are
first compared against the state of each alert rule. All other states are
ignored. If the alert rule matches then its alert instances are filtered
against states once more.
Alerts can also be filtered by labels using the `matcher` query string.
Like `state`, multiple matchers can be provided by adding additional
`matcher` query strings to the URL.
The match expression should be parsed using existing regular expression
and sent to the API as URL-encoded JSON in the format:
{
"name": "test",
"value": "value1",
"isRegex": false,
"isEqual": true
}
The `isRegex` and `isEqual` options work as follows:
| IsEqual | IsRegex | Operator |
| ------- | -------- | -------- |
| true | false | = |
| true | true | =~ |
| false | true | !~ |
| false | false | != |
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