prometheus/rules/recording.go
2016-12-29 17:31:14 +01:00

113 lines
2.9 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"
"time"
"golang.org/x/net/context"
"github.com/prometheus/prometheus/pkg/labels"
"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
}
// 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, _ string) (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 {
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,
template.HTMLEscapeString(rule.labels.String()),
pathPrefix+strutil.GraphLinkForExpression(ruleExpr),
template.HTMLEscapeString(ruleExpr)))
}