Initial commit of 'promtool check-metrics', promlint package (prometh…

…eus#2605)
kyle-hy · Apr 13, 2017 · 283756c · 283756c
1 parent ee62807
commit 283756c
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diff --git a/cmd/promtool/main.go b/cmd/promtool/main.go
@@ -24,6 +24,7 @@ import (
 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/util/cli"
+	"github.com/prometheus/prometheus/util/promlint"
 )
 
 // CheckConfigCmd validates configuration files.
@@ -182,6 +183,42 @@ func checkRules(t cli.Term, filename string) (int, error) {
 	return len(rules), nil
 }
 
+var checkMetricsUsage = strings.TrimSpace(`
+usage: promtool check-metrics
+
+Pass Prometheus metrics over stdin to lint them for consistency and correctness.
+
+examples:
+
+$ cat metrics.prom | promtool check-metrics
+$ curl -s http://localhost:9090/metrics | promtool check-metrics
+`)
+
+// CheckMetricsCmd performs a linting pass on input metrics.
+func CheckMetricsCmd(t cli.Term, args ...string) int {
+	if len(args) != 0 {
+		t.Infof(checkMetricsUsage)
+		return 2
+	}
+
+	l := promlint.New(os.Stdin)
+	problems, err := l.Lint()
+	if err != nil {
+		t.Errorf("error while linting: %v", err)
+		return 1
+	}
+
+	for _, p := range problems {
+		t.Errorf("%s: %s", p.Metric, p.Text)
+	}
+
+	if len(problems) > 0 {
+		return 3
+	}
+
+	return 0
+}
+
 // VersionCmd prints the binaries version information.
 func VersionCmd(t cli.Term, _ ...string) int {
 	fmt.Fprintln(os.Stdout, version.Print("promtool"))
@@ -201,6 +238,11 @@ func main() {
 		Run:  CheckRulesCmd,
 	})
 
+	app.Register("check-metrics", &cli.Command{
+		Desc: "validate metrics for correctness",
+		Run:  CheckMetricsCmd,
+	})
+
 	app.Register("version", &cli.Command{
 		Desc: "print the version of this binary",
 		Run:  VersionCmd,

diff --git a/util/promlint/promlint.go b/util/promlint/promlint.go
@@ -0,0 +1,198 @@
+// Copyright 2017 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 provides a linter for Prometheus metrics.
+package promlint
+
+import (
+	"fmt"
+	"io"
+	"sort"
+	"strings"
+
+	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/common/expfmt"
+)
+
+// A Linter is a Prometheus metrics linter.  It identifies issues with metric
+// names, types, and metadata, and reports them to the caller.
+type Linter struct {
+	r io.Reader
+}
+
+// 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
+}
+
+// New creates a new Linter that reads an input stream of Prometheus metrics.
+// Only the text exposition format is supported.
+func New(r io.Reader) *Linter {
+	return &Linter{
+		r: r,
+	}
+}
+
+// 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.
+func (l *Linter) Lint() ([]Problem, error) {
+	// TODO(mdlayher): support for protobuf exposition format?
+	d := expfmt.NewDecoder(l.r, expfmt.FmtText)
+
+	var problems []Problem
+
+	var mf dto.MetricFamily
+	for {
+		if err := d.Decode(&mf); err != nil {
+			if err == io.EOF {
+				break
+			}
+
+			return nil, err
+		}
+
+		problems = append(problems, lint(mf)...)
+	}
+
+	// Ensure deterministic output.
+	sort.SliceStable(problems, func(i, j int) bool {
+		if problems[i].Metric < problems[j].Metric {
+			return true
+		}
+
+		return problems[i].Text < problems[j].Text
+	})
+
+	return problems, nil
+}
+
+// lint is the entry point for linting a single metric.
+func lint(mf dto.MetricFamily) []Problem {
+	fns := []func(mf dto.MetricFamily) []Problem{
+		lintHelp,
+		lintMetricUnits,
+	}
+
+	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 {
+	var problems []Problem
+
+	// Expect all metrics to have help text available.
+	if mf.Help == nil {
+		problems = append(problems, Problem{
+			Metric: *mf.Name,
+			Text:   "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, Problem{
+		Metric: *mf.Name,
+		Text:   fmt.Sprintf("use base unit %q instead of %q", base, unit),
+	})
+
+	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 string, base string, ok bool) {
+	ss := strings.Split(m, "_")
+
+	for _, u := range baseUnits {
+		// Also check for "no prefix".
+		for _, p := range append(unitPrefixes, "") {
+			for _, s := range ss {
+				// Attempt to explicitly match a known unit with a known prefix,
+				// as some words may look like "units" when matching suffix.
+				//
+				// As an example, "thermometers" should not match "meters", but
+				// "kilometers" should.
+				if s == p+u {
+					return p + u, u, true
+				}
+			}
+		}
+	}
+
+	return "", "", false
+}
+
+// Units and their possible prefixes recognized by this library.  More can be
+// added over time as needed.
+var (
+	baseUnits = []string{
+		"amperes",
+		"bytes",
+		"candela",
+		"grams",
+		"kelvin", // Both plural and non-plural form allowed.
+		"kelvins",
+		"meters", // Both American and international spelling permitted.
+		"metres",
+		"moles",
+		"seconds",
+	}
+
+	unitPrefixes = []string{
+		"pico",
+		"nano",
+		"micro",
+		"milli",
+		"centi",
+		"deci",
+		"deca",
+		"hecto",
+		"kilo",
+		"kibi",
+		"mega",
+		"mibi",
+		"giga",
+		"gibi",
+		"tera",
+		"tebi",
+		"peta",
+		"pebi",
+	}
+)