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Add support for custom validations in promlint (#1311)
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* Refactor promlint validation structure

Signed-off-by: João Vilaça <jvilaca@redhat.com>

* Add support for custom validations in promlint

Signed-off-by: João Vilaça <jvilaca@redhat.com>

* Keep backwards compatibility

Signed-off-by: João Vilaça <jvilaca@redhat.com>

---------

Signed-off-by: João Vilaça <jvilaca@redhat.com>
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@machadovilaca
machadovilaca committed Oct 10, 2023
1 parent 486d514 commit 60a8513
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Showing 9 changed files with 497 additions and 285 deletions.
33 changes: 33 additions & 0 deletions prometheus/testutil/promlint/problem.go
View file
@@ -0,0 +1,33 @@
// Copyright 2020 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 promlint

import dto "github.com/prometheus/client_model/go"

// A Problem is an issue detected by a linter.
type Problem struct {
// The name of the metric indicated by this Problem.
Metric string

// A description of the issue for this Problem.
Text string
}

// newProblem is helper function to create a Problem.
func newProblem(mf *dto.MetricFamily, text string) Problem {
return Problem{
Metric: mf.GetName(),
Text: text,
}
}
308 changes: 23 additions & 285 deletions prometheus/testutil/promlint/promlint.go
View file
Expand Up @@ -16,15 +16,11 @@ package promlint

import (
"errors"
"fmt"
"io"
"regexp"
"sort"
"strings"

"github.com/prometheus/common/expfmt"

dto "github.com/prometheus/client_model/go"
"github.com/prometheus/common/expfmt"
)

// A Linter is a Prometheus metrics linter. It identifies issues with metric
Expand All @@ -37,23 +33,8 @@ type Linter struct {
// of them.
r io.Reader
mfs []*dto.MetricFamily
}

// A Problem is an issue detected by a Linter.
type Problem struct {
// The name of the metric indicated by this Problem.
Metric string

// A description of the issue for this Problem.
Text string
}

// newProblem is helper function to create a Problem.
func newProblem(mf *dto.MetricFamily, text string) Problem {
return Problem{
Metric: mf.GetName(),
Text: text,
}
customValidations []Validation
}

// New creates a new Linter that reads an input stream of Prometheus metrics in
Expand All @@ -72,6 +53,14 @@ func NewWithMetricFamilies(mfs []*dto.MetricFamily) *Linter {
}
}

// AddCustomValidations adds custom validations to the linter.
func (l *Linter) AddCustomValidations(vs ...Validation) {
if l.customValidations == nil {
l.customValidations = make([]Validation, 0, len(vs))
}
l.customValidations = append(l.customValidations, vs...)
}

// Lint performs a linting pass, returning a slice of Problems indicating any
// issues found in the metrics stream. The slice is sorted by metric name
// and issue description.
Expand All @@ -91,11 +80,11 @@ func (l *Linter) Lint() ([]Problem, error) {
return nil, err
}

problems = append(problems, lint(mf)...)
problems = append(problems, l.lint(mf)...)
}
}
for _, mf := range l.mfs {
problems = append(problems, lint(mf)...)
problems = append(problems, l.lint(mf)...)
}

// Ensure deterministic output.
Expand All @@ -110,276 +99,25 @@ func (l *Linter) Lint() ([]Problem, error) {
}

// lint is the entry point for linting a single metric.
func lint(mf *dto.MetricFamily) []Problem {
fns := []func(mf *dto.MetricFamily) []Problem{
lintHelp,
lintMetricUnits,
lintCounter,
lintHistogramSummaryReserved,
lintMetricTypeInName,
lintReservedChars,
lintCamelCase,
lintUnitAbbreviations,
}

var problems []Problem
for _, fn := range fns {
problems = append(problems, fn(mf)...)
}

// TODO(mdlayher): lint rules for specific metrics types.
return problems
}

// lintHelp detects issues related to the help text for a metric.
func lintHelp(mf *dto.MetricFamily) []Problem {
func (l *Linter) lint(mf *dto.MetricFamily) []Problem {
var problems []Problem

// Expect all metrics to have help text available.
if mf.Help == nil {
problems = append(problems, newProblem(mf, "no help text"))
}

return problems
}

// lintMetricUnits detects issues with metric unit names.
func lintMetricUnits(mf *dto.MetricFamily) []Problem {
var problems []Problem

unit, base, ok := metricUnits(*mf.Name)
if !ok {
// No known units detected.
return nil
}

// Unit is already a base unit.
if unit == base {
return nil
}

problems = append(problems, newProblem(mf, fmt.Sprintf("use base unit %q instead of %q", base, unit)))

return problems
}

// lintCounter detects issues specific to counters, as well as patterns that should
// only be used with counters.
func lintCounter(mf *dto.MetricFamily) []Problem {
var problems []Problem

isCounter := mf.GetType() == dto.MetricType_COUNTER
isUntyped := mf.GetType() == dto.MetricType_UNTYPED
hasTotalSuffix := strings.HasSuffix(mf.GetName(), "_total")

switch {
case isCounter && !hasTotalSuffix:
problems = append(problems, newProblem(mf, `counter metrics should have "_total" suffix`))
case !isUntyped && !isCounter && hasTotalSuffix:
problems = append(problems, newProblem(mf, `non-counter metrics should not have "_total" suffix`))
}

return problems
}

// lintHistogramSummaryReserved detects when other types of metrics use names or labels
// reserved for use by histograms and/or summaries.
func lintHistogramSummaryReserved(mf *dto.MetricFamily) []Problem {
// These rules do not apply to untyped metrics.
t := mf.GetType()
if t == dto.MetricType_UNTYPED {
return nil
}

var problems []Problem

isHistogram := t == dto.MetricType_HISTOGRAM
isSummary := t == dto.MetricType_SUMMARY

n := mf.GetName()

if !isHistogram && strings.HasSuffix(n, "_bucket") {
problems = append(problems, newProblem(mf, `non-histogram metrics should not have "_bucket" suffix`))
}
if !isHistogram && !isSummary && strings.HasSuffix(n, "_count") {
problems = append(problems, newProblem(mf, `non-histogram and non-summary metrics should not have "_count" suffix`))
}
if !isHistogram && !isSummary && strings.HasSuffix(n, "_sum") {
problems = append(problems, newProblem(mf, `non-histogram and non-summary metrics should not have "_sum" suffix`))
}

for _, m := range mf.GetMetric() {
for _, l := range m.GetLabel() {
ln := l.GetName()

if !isHistogram && ln == "le" {
problems = append(problems, newProblem(mf, `non-histogram metrics should not have "le" label`))
}
if !isSummary && ln == "quantile" {
problems = append(problems, newProblem(mf, `non-summary metrics should not have "quantile" label`))
}
}
}

return problems
}

// lintMetricTypeInName detects when metric types are included in the metric name.
func lintMetricTypeInName(mf *dto.MetricFamily) []Problem {
var problems []Problem
n := strings.ToLower(mf.GetName())

for i, t := range dto.MetricType_name {
if i == int32(dto.MetricType_UNTYPED) {
continue
for _, fn := range defaultValidations {
errs := fn(mf)
for _, err := range errs {
problems = append(problems, newProblem(mf, err.Error()))
}

typename := strings.ToLower(t)
if strings.Contains(n, "_"+typename+"_") || strings.HasSuffix(n, "_"+typename) {
problems = append(problems, newProblem(mf, fmt.Sprintf(`metric name should not include type '%s'`, typename)))
}
}
return problems
}

// lintReservedChars detects colons in metric names.
func lintReservedChars(mf *dto.MetricFamily) []Problem {
var problems []Problem
if strings.Contains(mf.GetName(), ":") {
problems = append(problems, newProblem(mf, "metric names should not contain ':'"))
}
return problems
}

var camelCase = regexp.MustCompile(`[a-z][A-Z]`)

// lintCamelCase detects metric names and label names written in camelCase.
func lintCamelCase(mf *dto.MetricFamily) []Problem {
var problems []Problem
if camelCase.FindString(mf.GetName()) != "" {
problems = append(problems, newProblem(mf, "metric names should be written in 'snake_case' not 'camelCase'"))
}

for _, m := range mf.GetMetric() {
for _, l := range m.GetLabel() {
if camelCase.FindString(l.GetName()) != "" {
problems = append(problems, newProblem(mf, "label names should be written in 'snake_case' not 'camelCase'"))
if l.customValidations != nil {
for _, fn := range l.customValidations {
errs := fn(mf)
for _, err := range errs {
problems = append(problems, newProblem(mf, err.Error()))
}
}
}
return problems
}

// lintUnitAbbreviations detects abbreviated units in the metric name.
func lintUnitAbbreviations(mf *dto.MetricFamily) []Problem {
var problems []Problem
n := strings.ToLower(mf.GetName())
for _, s := range unitAbbreviations {
if strings.Contains(n, "_"+s+"_") || strings.HasSuffix(n, "_"+s) {
problems = append(problems, newProblem(mf, "metric names should not contain abbreviated units"))
}
}
// TODO(mdlayher): lint rules for specific metrics types.
return problems
}

// metricUnits attempts to detect known unit types used as part of a metric name,
// e.g. "foo_bytes_total" or "bar_baz_milligrams".
func metricUnits(m string) (unit, base string, ok bool) {
ss := strings.Split(m, "_")

for _, s := range ss {
if base, found := units[s]; found {
return s, base, true
}

for _, p := range unitPrefixes {
if strings.HasPrefix(s, p) {
if base, found := units[s[len(p):]]; found {
return s, base, true
}
}
}
}

return "", "", false
}

// Units and their possible prefixes recognized by this library. More can be
// added over time as needed.
var (
// map a unit to the appropriate base unit.
units = map[string]string{
// Base units.
"amperes": "amperes",
"bytes": "bytes",
"celsius": "celsius", // Also allow Celsius because it is common in typical Prometheus use cases.
"grams": "grams",
"joules": "joules",
"kelvin": "kelvin", // SI base unit, used in special cases (e.g. color temperature, scientific measurements).
"meters": "meters", // Both American and international spelling permitted.
"metres": "metres",
"seconds": "seconds",
"volts": "volts",

// Non base units.
// Time.
"minutes": "seconds",
"hours": "seconds",
"days": "seconds",
"weeks": "seconds",
// Temperature.
"kelvins": "kelvin",
"fahrenheit": "celsius",
"rankine": "celsius",
// Length.
"inches": "meters",
"yards": "meters",
"miles": "meters",
// Bytes.
"bits": "bytes",
// Energy.
"calories": "joules",
// Mass.
"pounds": "grams",
"ounces": "grams",
}

unitPrefixes = []string{
"pico",
"nano",
"micro",
"milli",
"centi",
"deci",
"deca",
"hecto",
"kilo",
"kibi",
"mega",
"mibi",
"giga",
"gibi",
"tera",
"tebi",
"peta",
"pebi",
}

// Common abbreviations that we'd like to discourage.
unitAbbreviations = []string{
"s",
"ms",
"us",
"ns",
"sec",
"b",
"kb",
"mb",
"gb",
"tb",
"pb",
"m",
"h",
"d",
}
)

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