prometheus/rules/recording.go

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// Copyright 2013 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package rules
import (
"context"
"fmt"
"net/url"
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"time"
"go.uber.org/atomic"
"gopkg.in/yaml.v2"
"github.com/prometheus/prometheus/model/labels"
"github.com/prometheus/prometheus/model/rulefmt"
"github.com/prometheus/prometheus/promql"
"github.com/prometheus/prometheus/promql/parser"
)
// A RecordingRule records its vector expression into new timeseries.
type RecordingRule struct {
name string
vector parser.Expr
labels labels.Labels
// The health of the recording rule.
health *atomic.String
// Timestamp of last evaluation of the recording rule.
evaluationTimestamp *atomic.Time
// The last error seen by the recording rule.
lastError *atomic.Error
// Duration of how long it took to evaluate the recording rule.
evaluationDuration *atomic.Duration
}
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// NewRecordingRule returns a new recording rule.
func NewRecordingRule(name string, vector parser.Expr, lset labels.Labels) *RecordingRule {
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return &RecordingRule{
name: name,
vector: vector,
labels: lset,
health: atomic.NewString(string(HealthUnknown)),
evaluationTimestamp: atomic.NewTime(time.Time{}),
evaluationDuration: atomic.NewDuration(0),
lastError: atomic.NewError(nil),
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}
}
// Name returns the rule name.
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func (rule *RecordingRule) Name() string {
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return rule.name
}
// Query returns the rule query expression.
func (rule *RecordingRule) Query() parser.Expr {
return rule.vector
}
// Labels returns the rule labels.
func (rule *RecordingRule) Labels() labels.Labels {
return rule.labels
}
// Eval evaluates the rule and then overrides the metric names and labels accordingly.
func (rule *RecordingRule) Eval(ctx context.Context, ts time.Time, query QueryFunc, _ *url.URL, limit int) (promql.Vector, error) {
ctx = NewOriginContext(ctx, NewRuleDetail(rule))
vector, err := query(ctx, rule.vector.String(), ts)
if err != nil {
return nil, err
}
// Override the metric name and labels.
lb := labels.NewBuilder(labels.EmptyLabels())
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for i := range vector {
sample := &vector[i]
lb.Reset(sample.Metric)
lb.Set(labels.MetricName, rule.name)
rule.labels.Range(func(l labels.Label) {
lb.Set(l.Name, l.Value)
})
sample.Metric = lb.Labels(sample.Metric)
}
// Check that the rule does not produce identical metrics after applying
// labels.
if vector.ContainsSameLabelset() {
return nil, fmt.Errorf("vector contains metrics with the same labelset after applying rule labels")
}
numSeries := len(vector)
if limit > 0 && numSeries > limit {
return nil, fmt.Errorf("exceeded limit of %d with %d series", limit, numSeries)
}
rule.SetHealth(HealthGood)
rule.SetLastError(err)
return vector, nil
}
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func (rule *RecordingRule) String() string {
r := rulefmt.Rule{
Record: rule.name,
Expr: rule.vector.String(),
Labels: rule.labels.Map(),
}
byt, err := yaml.Marshal(r)
if err != nil {
return fmt.Sprintf("error marshaling recording rule: %q", err.Error())
}
return string(byt)
}
// SetEvaluationDuration updates evaluationDuration to the time in seconds it took to evaluate the rule on its last evaluation.
func (rule *RecordingRule) SetEvaluationDuration(dur time.Duration) {
rule.evaluationDuration.Store(dur)
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}
// SetLastError sets the current error seen by the recording rule.
func (rule *RecordingRule) SetLastError(err error) {
rule.lastError.Store(err)
}
// LastError returns the last error seen by the recording rule.
func (rule *RecordingRule) LastError() error {
return rule.lastError.Load()
}
// SetHealth sets the current health of the recording rule.
func (rule *RecordingRule) SetHealth(health RuleHealth) {
rule.health.Store(string(health))
}
// Health returns the current health of the recording rule.
func (rule *RecordingRule) Health() RuleHealth {
return RuleHealth(rule.health.Load())
}
// GetEvaluationDuration returns the time in seconds it took to evaluate the recording rule.
func (rule *RecordingRule) GetEvaluationDuration() time.Duration {
return rule.evaluationDuration.Load()
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}
// SetEvaluationTimestamp updates evaluationTimestamp to the timestamp of when the rule was last evaluated.
func (rule *RecordingRule) SetEvaluationTimestamp(ts time.Time) {
rule.evaluationTimestamp.Store(ts)
}
// GetEvaluationTimestamp returns the time the evaluation took place.
func (rule *RecordingRule) GetEvaluationTimestamp() time.Time {
return rule.evaluationTimestamp.Load()
}