Alerting: Add limits to the Prometheus Rules API (#65169)

This commit adds a number of limits to the Grafana flavor of the
Prometheus Rules API:

1. `limit` limits the maximum number of Rule Groups returned
2. `limit_rules` limits the maximum number of rules per Rule Group
3. `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.
This commit is contained in:
George Robinson
2023-04-03 10:17:02 +01:00
committed by GitHub
parent 093498a03b
commit d96b0a71d3
8 changed files with 613 additions and 23 deletions
@@ -1,6 +1,9 @@
package definitions
import (
"fmt"
"sort"
"strings"
"time"
v1 "github.com/prometheus/client_golang/api/prometheus/v1"
@@ -65,7 +68,8 @@ type DiscoveryBase struct {
// swagger:model
type RuleDiscovery struct {
// required: true
RuleGroups []*RuleGroup `json:"groups"`
RuleGroups []RuleGroup `json:"groups"`
Totals map[string]int64 `json:"totals,omitempty"`
}
// AlertDiscovery has info for all active alerts.
@@ -85,13 +89,37 @@ type RuleGroup struct {
// specific properties, both alerting and recording rules are exposed in the
// same array.
// required: true
Rules []AlertingRule `json:"rules"`
Rules []AlertingRule `json:"rules"`
Totals map[string]int64 `json:"totals"`
// required: true
Interval float64 `json:"interval"`
LastEvaluation time.Time `json:"lastEvaluation"`
EvaluationTime float64 `json:"evaluationTime"`
}
// RuleGroupsBy is a function that defines the ordering of Rule Groups.
type RuleGroupsBy func(a1, a2 *RuleGroup) bool
func (by RuleGroupsBy) Sort(groups []RuleGroup) {
sort.Sort(RuleGroupsSorter{groups: groups, by: by})
}
func RuleGroupsByFileAndName(a1, a2 *RuleGroup) bool {
if a1.File == a2.File {
return a1.Name < a2.Name
}
return a1.File < a2.File
}
type RuleGroupsSorter struct {
groups []RuleGroup
by RuleGroupsBy
}
func (s RuleGroupsSorter) Len() int { return len(s.groups) }
func (s RuleGroupsSorter) Swap(i, j int) { s.groups[i], s.groups[j] = s.groups[j], s.groups[i] }
func (s RuleGroupsSorter) Less(i, j int) bool { return s.by(&s.groups[i], &s.groups[j]) }
// adapted from cortex
// swagger:model
type AlertingRule struct {
@@ -106,7 +134,9 @@ type AlertingRule struct {
// required: true
Annotations overrideLabels `json:"annotations,omitempty"`
// required: true
Alerts []*Alert `json:"alerts,omitempty"`
ActiveAt *time.Time `json:"activeAt,omitempty"`
Alerts []Alert `json:"alerts,omitempty"`
Totals map[string]int64 `json:"totals,omitempty"`
Rule
}
@@ -141,6 +171,107 @@ type Alert struct {
Value string `json:"value"`
}
type StateByImportance int
const (
StateAlerting = iota
StatePending
StateError
StateNoData
StateNormal
)
func stateByImportanceFromString(s string) (StateByImportance, error) {
switch s = strings.ToLower(s); s {
case "alerting":
return StateAlerting, nil
case "pending":
return StatePending, nil
case "error":
return StateError, nil
case "nodata":
return StateNoData, nil
case "normal":
return StateNormal, nil
default:
return -1, fmt.Errorf("unknown state: %s", s)
}
}
// AlertsBy is a function that defines the ordering of alerts.
type AlertsBy func(a1, a2 *Alert) bool
func (by AlertsBy) Sort(alerts []Alert) {
sort.Sort(AlertsSorter{alerts: alerts, by: by})
}
// AlertsByImportance orders alerts by importance. An alert is more important
// than another alert if its status has higher importance. For example, "alerting"
// is more important than "normal". If two alerts have the same importance
// then the ordering is based on their ActiveAt time and their labels.
func AlertsByImportance(a1, a2 *Alert) bool {
// labelsForComparison concatenates each key/value pair into a string and
// sorts them.
labelsForComparison := func(m map[string]string) []string {
s := make([]string, 0, len(m))
for k, v := range m {
s = append(s, k+v)
}
sort.Strings(s)
return s
}
// compareLabels returns true if labels1 are less than labels2. This happens
// when labels1 has fewer labels than labels2, or if the next label from
// labels1 is lexicographically less than the next label from labels2.
compareLabels := func(labels1, labels2 []string) bool {
if len(labels1) == len(labels2) {
for i := range labels1 {
if labels1[i] != labels2[i] {
return labels1[i] < labels2[i]
}
}
}
return len(labels1) < len(labels2)
}
// The importance of an alert is first based on the importance of their states.
// This ordering is intended to show the most important alerts first when
// using pagination.
importance1, _ := stateByImportanceFromString(a1.State)
importance2, _ := stateByImportanceFromString(a2.State)
// If both alerts have the same importance then the ordering is based on
// their ActiveAt time, and if those are equal, their labels.
if importance1 == importance2 {
if a1.ActiveAt != nil && a2.ActiveAt == nil {
// The first alert is active but not the second
return true
} else if a1.ActiveAt == nil && a2.ActiveAt != nil {
// The second alert is active but not the first
return false
} else if a1.ActiveAt != nil && a2.ActiveAt != nil && a1.ActiveAt.Before(*a2.ActiveAt) {
// Both alerts are active but a1 happened before a2
return true
}
// Both alerts are active since the same time so compare their labels
labels1 := labelsForComparison(a1.Labels)
labels2 := labelsForComparison(a2.Labels)
return compareLabels(labels1, labels2)
}
return importance1 < importance2
}
type AlertsSorter struct {
alerts []Alert
by AlertsBy
}
func (s AlertsSorter) Len() int { return len(s.alerts) }
func (s AlertsSorter) Swap(i, j int) { s.alerts[i], s.alerts[j] = s.alerts[j], s.alerts[i] }
func (s AlertsSorter) Less(i, j int) bool { return s.by(&s.alerts[i], &s.alerts[j]) }
// override the labels type with a map for generation.
// The custom marshaling for labels.Labels ends up doing this anyways.
type overrideLabels map[string]string
@@ -0,0 +1,66 @@
package definitions
import (
"testing"
"time"
"github.com/stretchr/testify/assert"
)
func TestSortAlertsByImportance(t *testing.T) {
tm1, tm2 := time.Now(), time.Now().Add(time.Second)
tc := []struct {
name string
input []Alert
expected []Alert
}{{
name: "alerts are ordered in expected importance",
input: []Alert{{State: "normal"}, {State: "nodata"}, {State: "error"}, {State: "pending"}, {State: "alerting"}},
expected: []Alert{{State: "alerting"}, {State: "pending"}, {State: "error"}, {State: "nodata"}, {State: "normal"}},
}, {
name: "alerts with same importance are ordered active first",
input: []Alert{{State: "normal"}, {State: "normal", ActiveAt: &tm1}},
expected: []Alert{{State: "normal", ActiveAt: &tm1}, {State: "normal"}},
}, {
name: "active alerts with same importance are ordered newest first",
input: []Alert{{State: "alerting", ActiveAt: &tm2}, {State: "alerting", ActiveAt: &tm1}},
expected: []Alert{{State: "alerting", ActiveAt: &tm1}, {State: "alerting", ActiveAt: &tm2}},
}, {
name: "inactive alerts with same importance are ordered by labels",
input: []Alert{
{State: "normal", Labels: map[string]string{"c": "d"}},
{State: "normal", Labels: map[string]string{"a": "b"}},
},
expected: []Alert{
{State: "normal", Labels: map[string]string{"a": "b"}},
{State: "normal", Labels: map[string]string{"c": "d"}},
},
}, {
name: "active alerts with same importance and active time are ordered fewest labels first",
input: []Alert{
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"a": "b", "c": "d"}},
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"e": "f"}},
},
expected: []Alert{
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"e": "f"}},
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"a": "b", "c": "d"}},
},
}, {
name: "active alerts with same importance and active time are ordered by labels",
input: []Alert{
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"c": "d"}},
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"a": "b"}},
},
expected: []Alert{
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"a": "b"}},
{State: "alerting", ActiveAt: &tm1, Labels: map[string]string{"c": "d"}},
},
}}
for _, tt := range tc {
t.Run(tt.name, func(t *testing.T) {
AlertsBy(AlertsByImportance).Sort(tt.input)
assert.EqualValues(t, tt.expected, tt.input)
})
}
}