statsd_exporter/mapper.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 main
import (
"fmt"
"io/ioutil"
"regexp"
"strings"
"sync"
"github.com/prometheus/client_golang/prometheus"
)
var (
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identifierRE = `[a-zA-Z_][a-zA-Z0-9_]+`
statsdMetricRE = `[a-zA-Z_](-?[a-zA-Z0-9_])+`
metricLineRE = regexp.MustCompile(`^(\*\.|` + statsdMetricRE + `\.)+(\*|` + statsdMetricRE + `)$`)
labelLineRE = regexp.MustCompile(`^(` + identifierRE + `)\s*=\s*"(.*)"$`)
metricNameRE = regexp.MustCompile(`^` + identifierRE + `$`)
)
type metricMapping struct {
regex *regexp.Regexp
labels prometheus.Labels
}
type metricMapper struct {
mappings []metricMapping
mutex sync.Mutex
}
type configLoadStates int
const (
SEARCHING configLoadStates = iota
METRIC_DEFINITION
)
func (m *metricMapper) initFromString(fileContents string) error {
lines := strings.Split(fileContents, "\n")
numLines := len(lines)
state := SEARCHING
parsedMappings := []metricMapping{}
currentMapping := metricMapping{labels: prometheus.Labels{}}
for i, line := range lines {
line := strings.TrimSpace(line)
switch state {
case SEARCHING:
if line == "" {
continue
}
if !metricLineRE.MatchString(line) {
return fmt.Errorf("Line %d: expected metric match line, got: %s", i, line)
}
// Translate the glob-style metric match line into a proper regex that we
// can use to match metrics later on.
metricRe := strings.Replace(line, ".", "\\.", -1)
metricRe = strings.Replace(metricRe, "*", "([^.]+)", -1)
currentMapping.regex = regexp.MustCompile("^" + metricRe + "$")
state = METRIC_DEFINITION
case METRIC_DEFINITION:
if (i == numLines-1) && (line != "") {
return fmt.Errorf("Line %d: missing terminating newline", i)
}
if line == "" {
if len(currentMapping.labels) == 0 {
return fmt.Errorf("Line %d: metric mapping didn't set any labels", i)
}
if _, ok := currentMapping.labels["name"]; !ok {
return fmt.Errorf("Line %d: metric mapping didn't set a metric name", i)
}
parsedMappings = append(parsedMappings, currentMapping)
state = SEARCHING
currentMapping = metricMapping{labels: prometheus.Labels{}}
continue
}
if err := m.updateMapping(line, i, &currentMapping); err != nil {
return err
}
default:
panic("illegal state")
}
}
m.mutex.Lock()
defer m.mutex.Unlock()
m.mappings = parsedMappings
mappingsCount.Set(float64(len(parsedMappings)))
return nil
}
func (m *metricMapper) initFromFile(fileName string) error {
mappingStr, err := ioutil.ReadFile(fileName)
if err != nil {
return err
}
return m.initFromString(string(mappingStr))
}
func (m *metricMapper) getMapping(statsdMetric string) (labels prometheus.Labels, present bool) {
m.mutex.Lock()
defer m.mutex.Unlock()
for _, mapping := range m.mappings {
matches := mapping.regex.FindStringSubmatchIndex(statsdMetric)
if len(matches) == 0 {
continue
}
labels := prometheus.Labels{}
for label, valueExpr := range mapping.labels {
value := mapping.regex.ExpandString([]byte{}, valueExpr, statsdMetric, matches)
labels[label] = string(value)
}
return labels, true
}
return nil, false
}
func (m *metricMapper) updateMapping(line string, i int, mapping *metricMapping) error {
matches := labelLineRE.FindStringSubmatch(line)
if len(matches) != 3 {
return fmt.Errorf("Line %d: expected label mapping line, got: %s", i, line)
}
label, value := matches[1], matches[2]
if label == "name" && !metricNameRE.MatchString(value) {
return fmt.Errorf("Line %d: metric name '%s' doesn't match regex '%s'", i, value, metricNameRE)
}
(*mapping).labels[label] = value
return nil
}