prometheus/rules/recording.go
2017-11-22 15:22:02 +00:00

154 lines
4 KiB
Go

// 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"
"html/template"
"net/url"
"sync"
"time"
yaml "gopkg.in/yaml.v2"
"github.com/prometheus/prometheus/pkg/labels"
"github.com/prometheus/prometheus/pkg/rulefmt"
"github.com/prometheus/prometheus/promql"
"github.com/prometheus/prometheus/util/strutil"
)
// A RecordingRule records its vector expression into new timeseries.
type RecordingRule struct {
name string
vector promql.Expr
labels labels.Labels
mtx sync.Mutex
evaluationTimeSeconds float64
}
// NewRecordingRule returns a new recording rule.
func NewRecordingRule(name string, vector promql.Expr, lset labels.Labels) *RecordingRule {
return &RecordingRule{
name: name,
vector: vector,
labels: lset,
}
}
// Name returns the rule name.
func (rule *RecordingRule) Name() string {
return rule.name
}
// Eval evaluates the rule and then overrides the metric names and labels accordingly.
func (rule *RecordingRule) Eval(ctx context.Context, ts time.Time, engine *promql.Engine, _ *url.URL) (promql.Vector, error) {
query, err := engine.NewInstantQuery(rule.vector.String(), ts)
if err != nil {
return nil, err
}
var (
result = query.Exec(ctx)
vector promql.Vector
)
if result.Err != nil {
return nil, err
}
switch v := result.Value.(type) {
case promql.Vector:
vector = v
case promql.Scalar:
vector = promql.Vector{promql.Sample{
Point: promql.Point(v),
Metric: labels.Labels{},
}}
default:
return nil, fmt.Errorf("rule result is not a vector or scalar")
}
// Override the metric name and labels.
for i := range vector {
sample := &vector[i]
lb := labels.NewBuilder(sample.Metric)
lb.Set(labels.MetricName, rule.name)
for _, l := range rule.labels {
if l.Value == "" {
lb.Del(l.Name)
} else {
lb.Set(l.Name, l.Value)
}
}
sample.Metric = lb.Labels()
}
return vector, nil
}
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 marshalling recording rule: %q", err.Error())
}
return string(byt)
}
// setEvaluationTimeSeconds updates evaluationTimeSeconds to the time in seconds it took to evaluate the rule on its last evaluation.
func (rule *RecordingRule) setEvaluationTimeSeconds(seconds float64) {
rule.mtx.Lock()
defer rule.mtx.Unlock()
rule.evaluationTimeSeconds = seconds
}
// GetEvaluationTimeSeconds returns the time in seconds it took to evaluate the recording rule.
func (rule *RecordingRule) GetEvaluationTimeSeconds() float64 {
rule.mtx.Lock()
defer rule.mtx.Unlock()
return rule.evaluationTimeSeconds
}
// HTMLSnippet returns an HTML snippet representing this rule.
func (rule *RecordingRule) HTMLSnippet(pathPrefix string) template.HTML {
ruleExpr := rule.vector.String()
labels := make(map[string]string, len(rule.labels))
for _, l := range rule.labels {
labels[l.Name] = template.HTMLEscapeString(l.Value)
}
r := rulefmt.Rule{
Record: fmt.Sprintf(`<a href="%s">%s</a>`, pathPrefix+strutil.TableLinkForExpression(rule.name), rule.name),
Expr: fmt.Sprintf(`<a href="%s">%s</a>`, pathPrefix+strutil.TableLinkForExpression(ruleExpr), template.HTMLEscapeString(ruleExpr)),
Labels: labels,
}
byt, err := yaml.Marshal(r)
if err != nil {
return template.HTML(fmt.Sprintf("error marshalling recording rule: %q", err.Error()))
}
return template.HTML(byt)
}