prometheus/rules/recording.go

100 lines
2.8 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 (
"fmt"
"html/template"
clientmodel "github.com/prometheus/client_golang/model"
"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 clientmodel.LabelSet
}
// NewRecordingRule returns a new recording rule.
func NewRecordingRule(name string, vector promql.Expr, labels clientmodel.LabelSet) *RecordingRule {
return &RecordingRule{
name: name,
vector: vector,
labels: labels,
}
}
// 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(timestamp clientmodel.Timestamp, engine *promql.Engine) (promql.Vector, error) {
query, err := engine.NewInstantQuery(rule.vector.String(), timestamp)
if err != nil {
return nil, err
}
result := query.Exec()
var vector promql.Vector
switch result.Value.(type) {
case promql.Vector:
vector, err = result.Vector()
if err != nil {
return nil, err
}
case *promql.Scalar:
scalar, err := result.Scalar()
if err != nil {
return nil, err
}
vector = promql.Vector{&promql.Sample{Value: scalar.Value, Timestamp: scalar.Timestamp}}
default:
return nil, fmt.Errorf("rule result is not a vector or scalar")
}
// Override the metric name and labels.
for _, sample := range vector {
sample.Metric.Set(clientmodel.MetricNameLabel, clientmodel.LabelValue(rule.name))
for label, value := range rule.labels {
if value == "" {
sample.Metric.Delete(label)
} else {
sample.Metric.Set(label, value)
}
}
}
return vector, nil
}
func (rule RecordingRule) String() string {
return fmt.Sprintf("%s%s = %s\n", rule.name, rule.labels, rule.vector)
}
// HTMLSnippet returns an HTML snippet representing this rule.
func (rule RecordingRule) HTMLSnippet(pathPrefix string) template.HTML {
ruleExpr := rule.vector.String()
return template.HTML(fmt.Sprintf(
`<a href="%s">%s</a>%s = <a href="%s">%s</a>`,
pathPrefix+strutil.GraphLinkForExpression(rule.name),
rule.name,
rule.labels,
pathPrefix+strutil.GraphLinkForExpression(ruleExpr),
ruleExpr))
}