forked from mirror/client_golang
373 lines
9.2 KiB
Go
373 lines
9.2 KiB
Go
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// Copyright 2017 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package promlint provides a linter for Prometheus metrics.
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package promlint
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import (
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"fmt"
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"io"
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"regexp"
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"sort"
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"strings"
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dto "github.com/prometheus/client_model/go"
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"github.com/prometheus/common/expfmt"
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)
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// A Linter is a Prometheus metrics linter. It identifies issues with metric
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// names, types, and metadata, and reports them to the caller.
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type Linter struct {
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r io.Reader
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}
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// A Problem is an issue detected by a Linter.
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type Problem struct {
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// The name of the metric indicated by this Problem.
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Metric string
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// A description of the issue for this Problem.
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Text string
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}
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// problems is a slice of Problems with a helper method to easily append
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// additional Problems to the slice.
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type problems []Problem
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// Add appends a new Problem to the slice for the specified metric, with
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// the specified issue text.
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func (p *problems) Add(mf dto.MetricFamily, text string) {
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*p = append(*p, Problem{
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Metric: mf.GetName(),
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Text: text,
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})
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}
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// New creates a new Linter that reads an input stream of Prometheus metrics.
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// Only the text exposition format is supported.
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func New(r io.Reader) *Linter {
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return &Linter{
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r: r,
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}
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}
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// Lint performs a linting pass, returning a slice of Problems indicating any
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// issues found in the metrics stream. The slice is sorted by metric name
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// and issue description.
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func (l *Linter) Lint() ([]Problem, error) {
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// TODO(mdlayher): support for protobuf exposition format?
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d := expfmt.NewDecoder(l.r, expfmt.FmtText)
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var problems []Problem
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var mf dto.MetricFamily
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for {
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if err := d.Decode(&mf); err != nil {
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if err == io.EOF {
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break
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}
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return nil, err
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}
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problems = append(problems, lint(mf)...)
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}
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// Ensure deterministic output.
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sort.SliceStable(problems, func(i, j int) bool {
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if problems[i].Metric == problems[j].Metric {
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return problems[i].Text < problems[j].Text
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}
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return problems[i].Metric < problems[j].Metric
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})
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return problems, nil
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}
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// lint is the entry point for linting a single metric.
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func lint(mf dto.MetricFamily) []Problem {
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fns := []func(mf dto.MetricFamily) []Problem{
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lintHelp,
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lintMetricUnits,
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lintCounter,
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lintHistogramSummaryReserved,
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lintMetricTypeInName,
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lintReservedChars,
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lintCamelCase,
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lintUnitAbbreviations,
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}
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var problems []Problem
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for _, fn := range fns {
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problems = append(problems, fn(mf)...)
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}
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// TODO(mdlayher): lint rules for specific metrics types.
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return problems
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}
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// lintHelp detects issues related to the help text for a metric.
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func lintHelp(mf dto.MetricFamily) []Problem {
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var problems problems
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// Expect all metrics to have help text available.
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if mf.Help == nil {
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problems.Add(mf, "no help text")
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}
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return problems
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}
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// lintMetricUnits detects issues with metric unit names.
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func lintMetricUnits(mf dto.MetricFamily) []Problem {
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var problems problems
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unit, base, ok := metricUnits(*mf.Name)
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if !ok {
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// No known units detected.
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return nil
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}
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// Unit is already a base unit.
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if unit == base {
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return nil
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}
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problems.Add(mf, fmt.Sprintf("use base unit %q instead of %q", base, unit))
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return problems
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}
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// lintCounter detects issues specific to counters, as well as patterns that should
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// only be used with counters.
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func lintCounter(mf dto.MetricFamily) []Problem {
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var problems problems
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isCounter := mf.GetType() == dto.MetricType_COUNTER
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isUntyped := mf.GetType() == dto.MetricType_UNTYPED
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hasTotalSuffix := strings.HasSuffix(mf.GetName(), "_total")
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switch {
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case isCounter && !hasTotalSuffix:
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problems.Add(mf, `counter metrics should have "_total" suffix`)
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case !isUntyped && !isCounter && hasTotalSuffix:
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problems.Add(mf, `non-counter metrics should not have "_total" suffix`)
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}
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return problems
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}
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// lintHistogramSummaryReserved detects when other types of metrics use names or labels
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// reserved for use by histograms and/or summaries.
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func lintHistogramSummaryReserved(mf dto.MetricFamily) []Problem {
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// These rules do not apply to untyped metrics.
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t := mf.GetType()
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if t == dto.MetricType_UNTYPED {
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return nil
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}
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var problems problems
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isHistogram := t == dto.MetricType_HISTOGRAM
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isSummary := t == dto.MetricType_SUMMARY
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n := mf.GetName()
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if !isHistogram && strings.HasSuffix(n, "_bucket") {
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problems.Add(mf, `non-histogram metrics should not have "_bucket" suffix`)
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}
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if !isHistogram && !isSummary && strings.HasSuffix(n, "_count") {
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problems.Add(mf, `non-histogram and non-summary metrics should not have "_count" suffix`)
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}
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if !isHistogram && !isSummary && strings.HasSuffix(n, "_sum") {
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problems.Add(mf, `non-histogram and non-summary metrics should not have "_sum" suffix`)
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}
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for _, m := range mf.GetMetric() {
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for _, l := range m.GetLabel() {
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ln := l.GetName()
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if !isHistogram && ln == "le" {
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problems.Add(mf, `non-histogram metrics should not have "le" label`)
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}
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if !isSummary && ln == "quantile" {
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problems.Add(mf, `non-summary metrics should not have "quantile" label`)
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}
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}
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}
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return problems
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}
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// lintMetricTypeInName detects when metric types are included in the metric name.
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func lintMetricTypeInName(mf dto.MetricFamily) []Problem {
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var problems problems
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n := strings.ToLower(mf.GetName())
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for i, t := range dto.MetricType_name {
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if i == int32(dto.MetricType_UNTYPED) {
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continue
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}
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typename := strings.ToLower(t)
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if strings.Contains(n, "_"+typename+"_") || strings.HasSuffix(n, "_"+typename) {
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problems.Add(mf, fmt.Sprintf(`metric name should not include type '%s'`, typename))
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}
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}
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return problems
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}
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// lintReservedChars detects colons in metric names.
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func lintReservedChars(mf dto.MetricFamily) []Problem {
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var problems problems
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if strings.Contains(mf.GetName(), ":") {
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problems.Add(mf, "metric names should not contain ':'")
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}
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return problems
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}
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var camelCase = regexp.MustCompile(`[a-z][A-Z]`)
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// lintCamelCase detects metric names and label names written in camelCase.
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func lintCamelCase(mf dto.MetricFamily) []Problem {
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var problems problems
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if camelCase.FindString(mf.GetName()) != "" {
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problems.Add(mf, "metric names should be written in 'snake_case' not 'camelCase'")
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}
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for _, m := range mf.GetMetric() {
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for _, l := range m.GetLabel() {
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if camelCase.FindString(l.GetName()) != "" {
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problems.Add(mf, "label names should be written in 'snake_case' not 'camelCase'")
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}
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}
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}
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return problems
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}
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// lintUnitAbbreviations detects abbreviated units in the metric name.
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func lintUnitAbbreviations(mf dto.MetricFamily) []Problem {
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var problems problems
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n := strings.ToLower(mf.GetName())
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for _, s := range unitAbbreviations {
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if strings.Contains(n, "_"+s+"_") || strings.HasSuffix(n, "_"+s) {
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problems.Add(mf, "metric names should not contain abbreviated units")
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}
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}
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return problems
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}
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// metricUnits attempts to detect known unit types used as part of a metric name,
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// e.g. "foo_bytes_total" or "bar_baz_milligrams".
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func metricUnits(m string) (unit string, base string, ok bool) {
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ss := strings.Split(m, "_")
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for unit, base := range units {
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// Also check for "no prefix".
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for _, p := range append(unitPrefixes, "") {
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for _, s := range ss {
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// Attempt to explicitly match a known unit with a known prefix,
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// as some words may look like "units" when matching suffix.
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//
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// As an example, "thermometers" should not match "meters", but
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// "kilometers" should.
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if s == p+unit {
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return p + unit, base, true
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}
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}
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}
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}
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return "", "", false
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}
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// Units and their possible prefixes recognized by this library. More can be
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// added over time as needed.
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var (
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// map a unit to the appropriate base unit.
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units = map[string]string{
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// Base units.
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"amperes": "amperes",
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"bytes": "bytes",
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"celsius": "celsius", // Celsius is more common in practice than Kelvin.
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"grams": "grams",
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"joules": "joules",
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"meters": "meters", // Both American and international spelling permitted.
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"metres": "metres",
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"seconds": "seconds",
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"volts": "volts",
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// Non base units.
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// Time.
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"minutes": "seconds",
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"hours": "seconds",
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"days": "seconds",
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"weeks": "seconds",
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// Temperature.
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"kelvin": "celsius",
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"kelvins": "celsius",
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"fahrenheit": "celsius",
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"rankine": "celsius",
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// Length.
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"inches": "meters",
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"yards": "meters",
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"miles": "meters",
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// Bytes.
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"bits": "bytes",
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// Energy.
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"calories": "joules",
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// Mass.
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"pounds": "grams",
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"ounces": "grams",
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}
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unitPrefixes = []string{
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"pico",
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"nano",
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"micro",
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"milli",
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"centi",
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"deci",
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"deca",
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"hecto",
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"kilo",
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"kibi",
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"mega",
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"mibi",
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"giga",
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"gibi",
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"tera",
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"tebi",
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"peta",
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"pebi",
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}
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// Common abbreviations that we'd like to discourage.
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unitAbbreviations = []string{
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"s",
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"ms",
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"us",
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"ns",
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"sec",
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"b",
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"kb",
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"mb",
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"gb",
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"tb",
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"pb",
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"m",
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"h",
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"d",
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}
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)
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