client_golang/prometheus/promhttp/instrument_server_test.go

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// 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 promhttp
import (
"context"
"io"
"log"
"net/http"
"net/http/httptest"
"testing"
"github.com/prometheus/client_golang/prometheus"
)
func TestLabelCheck(t *testing.T) {
scenarios := map[string]struct {
metricName string // Defaults to "c".
varLabels []string
constLabels []string
curriedLabels []string
dynamicLabels []string
ok bool
}{
"empty": {
varLabels: []string{},
constLabels: []string{},
curriedLabels: []string{},
ok: true,
},
"code as single var label": {
varLabels: []string{"code"},
constLabels: []string{},
curriedLabels: []string{},
ok: true,
},
"method as single var label": {
varLabels: []string{"method"},
constLabels: []string{},
curriedLabels: []string{},
ok: true,
},
"code and method as var labels": {
varLabels: []string{"method", "code"},
constLabels: []string{},
curriedLabels: []string{},
ok: true,
},
"valid case with all labels used": {
varLabels: []string{"code", "method"},
constLabels: []string{"foo", "bar"},
curriedLabels: []string{"dings", "bums"},
dynamicLabels: []string{"dyn", "amics"},
ok: true,
},
"all labels used with an invalid const label name": {
varLabels: []string{"code", "method"},
constLabels: []string{"in-valid", "bar"},
curriedLabels: []string{"dings", "bums"},
dynamicLabels: []string{"dyn", "amics"},
ok: false,
},
"unsupported var label": {
varLabels: []string{"foo"},
constLabels: []string{},
curriedLabels: []string{},
ok: false,
},
"mixed var labels": {
varLabels: []string{"method", "foo", "code"},
constLabels: []string{},
curriedLabels: []string{},
ok: false,
},
"unsupported var label but curried": {
varLabels: []string{},
constLabels: []string{},
curriedLabels: []string{"foo"},
ok: true,
},
"mixed var labels but unsupported curried": {
varLabels: []string{"code", "method"},
constLabels: []string{},
curriedLabels: []string{"foo"},
ok: true,
},
"supported label as const and curry": {
varLabels: []string{},
constLabels: []string{"code"},
curriedLabels: []string{"method"},
ok: true,
},
"supported label as const and dynamic": {
varLabels: []string{},
constLabels: []string{"code"},
dynamicLabels: []string{"method"},
ok: true,
},
"supported label as curried and dynamic": {
varLabels: []string{},
curriedLabels: []string{"code"},
dynamicLabels: []string{"method"},
ok: true,
},
"supported label as const and curry with unsupported as var": {
varLabels: []string{"foo"},
constLabels: []string{"code"},
curriedLabels: []string{"method"},
ok: false,
},
"invalid name and otherwise empty": {
metricName: "in-valid",
varLabels: []string{},
constLabels: []string{},
curriedLabels: []string{},
ok: false,
},
"invalid name with all the otherwise valid labels": {
metricName: "in-valid",
varLabels: []string{"code", "method"},
constLabels: []string{"foo", "bar"},
curriedLabels: []string{"dings", "bums"},
dynamicLabels: []string{"dyn", "amics"},
ok: false,
},
}
for name, sc := range scenarios {
t.Run(name, func(t *testing.T) {
metricName := sc.metricName
if metricName == "" {
metricName = "c"
}
constLabels := prometheus.Labels{}
for _, l := range sc.constLabels {
constLabels[l] = "dummy"
}
labelNames := append(append(sc.varLabels, sc.curriedLabels...), sc.dynamicLabels...)
c := prometheus.V2.NewCounterVec(
prometheus.CounterVecOpts{
CounterOpts: prometheus.CounterOpts{
Name: metricName,
Help: "c help",
ConstLabels: constLabels,
},
VariableLabels: prometheus.UnconstrainedLabels(labelNames),
},
)
o := prometheus.ObserverVec(prometheus.V2.NewHistogramVec(
prometheus.HistogramVecOpts{
HistogramOpts: prometheus.HistogramOpts{
Name: metricName,
Help: "c help",
ConstLabels: constLabels,
},
VariableLabels: prometheus.UnconstrainedLabels(labelNames),
},
))
for _, l := range sc.curriedLabels {
c = c.MustCurryWith(prometheus.Labels{l: "dummy"})
o = o.MustCurryWith(prometheus.Labels{l: "dummy"})
}
opts := []Option{}
for _, l := range sc.dynamicLabels {
opts = append(opts, WithLabelFromCtx(l,
func(_ context.Context) string {
return "foo"
},
))
}
func() {
defer func() {
if err := recover(); err != nil {
if sc.ok {
t.Error("unexpected panic:", err)
}
} else if !sc.ok {
t.Error("expected panic")
}
}()
InstrumentHandlerCounter(c, nil, opts...)
}()
func() {
defer func() {
if err := recover(); err != nil {
if sc.ok {
t.Error("unexpected panic:", err)
}
} else if !sc.ok {
t.Error("expected panic")
}
}()
InstrumentHandlerDuration(o, nil, opts...)
}()
if sc.ok {
// Test if wantCode and wantMethod were detected correctly.
var wantCode, wantMethod bool
for _, l := range sc.varLabels {
if l == "code" {
wantCode = true
}
if l == "method" {
wantMethod = true
}
}
// Curry the dynamic labels since this is done normally behind the scenes for the check
for _, l := range sc.dynamicLabels {
c = c.MustCurryWith(prometheus.Labels{l: "dummy"})
o = o.MustCurryWith(prometheus.Labels{l: "dummy"})
}
gotCode, gotMethod := checkLabels(c)
if gotCode != wantCode {
t.Errorf("wanted code=%t for counter, got code=%t", wantCode, gotCode)
}
if gotMethod != wantMethod {
t.Errorf("wanted method=%t for counter, got method=%t", wantMethod, gotMethod)
}
gotCode, gotMethod = checkLabels(o)
if gotCode != wantCode {
t.Errorf("wanted code=%t for observer, got code=%t", wantCode, gotCode)
}
if gotMethod != wantMethod {
t.Errorf("wanted method=%t for observer, got method=%t", wantMethod, gotMethod)
}
}
})
}
}
func TestLabels(t *testing.T) {
scenarios := map[string]struct {
varLabels []string
reqMethod string
respStatus int
extraMethods []string
wantLabels prometheus.Labels
ok bool
}{
"empty": {
varLabels: []string{},
wantLabels: emptyLabels,
reqMethod: "GET",
respStatus: 200,
ok: true,
},
"code as single var label": {
varLabels: []string{"code"},
reqMethod: "GET",
respStatus: 200,
wantLabels: prometheus.Labels{"code": "200"},
ok: true,
},
"code as single var label and out-of-range code": {
varLabels: []string{"code"},
reqMethod: "GET",
respStatus: 99,
wantLabels: prometheus.Labels{"code": "unknown"},
ok: true,
},
"code as single var label and in-range but unrecognized code": {
varLabels: []string{"code"},
reqMethod: "GET",
respStatus: 308,
wantLabels: prometheus.Labels{"code": "308"},
ok: true,
},
"method as single var label": {
varLabels: []string{"method"},
reqMethod: "GET",
respStatus: 200,
wantLabels: prometheus.Labels{"method": "get"},
ok: true,
},
"method as single var label and unknown method": {
varLabels: []string{"method"},
reqMethod: "CUSTOM_METHOD",
respStatus: 200,
wantLabels: prometheus.Labels{"method": "unknown"},
ok: true,
},
"code and method as var labels": {
varLabels: []string{"method", "code"},
reqMethod: "GET",
respStatus: 200,
wantLabels: prometheus.Labels{"method": "get", "code": "200"},
ok: true,
},
"method as single var label with extra methods specified": {
varLabels: []string{"method"},
reqMethod: "CUSTOM_METHOD",
respStatus: 200,
extraMethods: []string{"CUSTOM_METHOD", "CUSTOM_METHOD_1"},
wantLabels: prometheus.Labels{"method": "custom_method"},
ok: true,
},
"all labels used with an unknown method and out-of-range code": {
varLabels: []string{"code", "method"},
reqMethod: "CUSTOM_METHOD",
respStatus: 99,
wantLabels: prometheus.Labels{"method": "unknown", "code": "unknown"},
ok: false,
},
}
checkLabels := func(labels []string) (gotCode, gotMethod bool) {
for _, label := range labels {
switch label {
case "code":
gotCode = true
case "method":
gotMethod = true
default:
panic("metric partitioned with non-supported labels for this test")
}
}
return
}
equalLabels := func(gotLabels, wantLabels prometheus.Labels) bool {
if len(gotLabels) != len(wantLabels) {
return false
}
for ln, lv := range gotLabels {
olv, ok := wantLabels[ln]
if !ok {
return false
}
if olv != lv {
return false
}
}
return true
}
for name, sc := range scenarios {
t.Run(name, func(t *testing.T) {
if sc.ok {
gotCode, gotMethod := checkLabels(sc.varLabels)
gotLabels := labels(gotCode, gotMethod, sc.reqMethod, sc.respStatus, sc.extraMethods...)
if !equalLabels(gotLabels, sc.wantLabels) {
t.Errorf("wanted labels=%v for counter, got code=%v", sc.wantLabels, gotLabels)
}
}
})
}
}
func makeInstrumentedHandler(handler http.HandlerFunc, opts ...Option) (http.Handler, *prometheus.Registry) {
reg := prometheus.NewRegistry()
inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
Name: "in_flight_requests",
Help: "A gauge of requests currently being served by the wrapped handler.",
})
counter := prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "api_requests_total",
Help: "A counter for requests to the wrapped handler.",
},
[]string{"code", "method"},
)
histVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "response_duration_seconds",
Help: "A histogram of request latencies.",
Buckets: prometheus.DefBuckets,
ConstLabels: prometheus.Labels{"handler": "api"},
},
[]string{"method"},
)
writeHeaderVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "write_header_duration_seconds",
Help: "A histogram of time to first write latencies.",
Buckets: prometheus.DefBuckets,
ConstLabels: prometheus.Labels{"handler": "api"},
},
[]string{},
)
responseSize := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "push_request_size_bytes",
Help: "A histogram of request sizes for requests.",
Buckets: []float64{200, 500, 900, 1500},
},
[]string{},
)
reg.MustRegister(inFlightGauge, counter, histVec, responseSize, writeHeaderVec)
return InstrumentHandlerInFlight(inFlightGauge,
InstrumentHandlerCounter(counter,
InstrumentHandlerDuration(histVec,
InstrumentHandlerTimeToWriteHeader(writeHeaderVec,
InstrumentHandlerResponseSize(responseSize, handler, opts...),
opts...),
opts...),
opts...),
), reg
}
func TestMiddlewareAPI(t *testing.T) {
chain, reg := makeInstrumentedHandler(func(w http.ResponseWriter, r *http.Request) {
_, _ = w.Write([]byte("OK"))
})
r, _ := http.NewRequest("GET", "www.example.com", nil)
w := httptest.NewRecorder()
chain.ServeHTTP(w, r)
assetMetricAndExemplars(t, reg, 5, nil)
}
func TestMiddlewareAPI_WithExemplars(t *testing.T) {
exemplar := prometheus.Labels{"traceID": "example situation observed by this metric"}
chain, reg := makeInstrumentedHandler(func(w http.ResponseWriter, r *http.Request) {
_, _ = w.Write([]byte("OK"))
}, WithExemplarFromContext(func(_ context.Context) prometheus.Labels { return exemplar }))
r, _ := http.NewRequest("GET", "www.example.com", nil)
w := httptest.NewRecorder()
chain.ServeHTTP(w, r)
assetMetricAndExemplars(t, reg, 5, labelsToLabelPair(exemplar))
}
func TestInstrumentTimeToFirstWrite(t *testing.T) {
var i int
dobs := &responseWriterDelegator{
ResponseWriter: httptest.NewRecorder(),
observeWriteHeader: func(status int) {
i = status
},
}
d := newDelegator(dobs, nil)
d.WriteHeader(http.StatusOK)
if i != http.StatusOK {
t.Fatalf("failed to execute observeWriteHeader")
}
}
// testResponseWriter is an http.ResponseWriter that also implements
// http.CloseNotifier, http.Flusher, and io.ReaderFrom.
type testResponseWriter struct {
closeNotifyCalled, flushCalled, readFromCalled bool
}
func (t *testResponseWriter) Header() http.Header { return nil }
func (t *testResponseWriter) Write([]byte) (int, error) { return 0, nil }
func (t *testResponseWriter) WriteHeader(int) {}
func (t *testResponseWriter) CloseNotify() <-chan bool {
t.closeNotifyCalled = true
return nil
}
func (t *testResponseWriter) Flush() { t.flushCalled = true }
func (t *testResponseWriter) ReadFrom(io.Reader) (int64, error) {
t.readFromCalled = true
return 0, nil
}
// testFlusher is an http.ResponseWriter that also implements http.Flusher.
type testFlusher struct {
flushCalled bool
}
func (t *testFlusher) Header() http.Header { return nil }
func (t *testFlusher) Write([]byte) (int, error) { return 0, nil }
func (t *testFlusher) WriteHeader(int) {}
func (t *testFlusher) Flush() { t.flushCalled = true }
func TestInterfaceUpgrade(t *testing.T) {
w := &testResponseWriter{}
d := newDelegator(w, nil)
//nolint:staticcheck // Ignore SA1019. http.CloseNotifier is deprecated but we keep it here to not break existing users.
d.(http.CloseNotifier).CloseNotify()
if !w.closeNotifyCalled {
t.Error("CloseNotify not called")
}
d.(http.Flusher).Flush()
if !w.flushCalled {
t.Error("Flush not called")
}
d.(io.ReaderFrom).ReadFrom(nil)
if !w.readFromCalled {
t.Error("ReadFrom not called")
}
if _, ok := d.(http.Hijacker); ok {
t.Error("delegator unexpectedly implements http.Hijacker")
}
f := &testFlusher{}
d = newDelegator(f, nil)
//nolint:staticcheck // Ignore SA1019. http.CloseNotifier is deprecated but we keep it here to not break existing users.
if _, ok := d.(http.CloseNotifier); ok {
t.Error("delegator unexpectedly implements http.CloseNotifier")
}
d.(http.Flusher).Flush()
if !w.flushCalled {
t.Error("Flush not called")
}
if _, ok := d.(io.ReaderFrom); ok {
t.Error("delegator unexpectedly implements io.ReaderFrom")
}
if _, ok := d.(http.Hijacker); ok {
t.Error("delegator unexpectedly implements http.Hijacker")
}
}
func ExampleInstrumentHandlerDuration() {
inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
Name: "in_flight_requests",
Help: "A gauge of requests currently being served by the wrapped handler.",
})
counter := prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "api_requests_total",
Help: "A counter for requests to the wrapped handler.",
},
[]string{"code", "method"},
)
// duration is partitioned by the HTTP method and handler. It uses custom
// buckets based on the expected request duration.
duration := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "request_duration_seconds",
Help: "A histogram of latencies for requests.",
Buckets: []float64{.25, .5, 1, 2.5, 5, 10},
},
[]string{"handler", "method"},
)
// responseSize has no labels, making it a zero-dimensional
// ObserverVec.
responseSize := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "response_size_bytes",
Help: "A histogram of response sizes for requests.",
Buckets: []float64{200, 500, 900, 1500},
},
[]string{},
)
// Create the handlers that will be wrapped by the middleware.
pushHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("Push"))
})
pullHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("Pull"))
})
// Register all of the metrics in the standard registry.
prometheus.MustRegister(inFlightGauge, counter, duration, responseSize)
// Instrument the handlers with all the metrics, injecting the "handler"
// label by currying.
pushChain := InstrumentHandlerInFlight(inFlightGauge,
InstrumentHandlerDuration(duration.MustCurryWith(prometheus.Labels{"handler": "push"}),
InstrumentHandlerCounter(counter,
InstrumentHandlerResponseSize(responseSize, pushHandler),
),
),
)
pullChain := InstrumentHandlerInFlight(inFlightGauge,
InstrumentHandlerDuration(duration.MustCurryWith(prometheus.Labels{"handler": "pull"}),
InstrumentHandlerCounter(counter,
InstrumentHandlerResponseSize(responseSize, pullHandler),
),
),
)
http.Handle("/metrics", Handler())
http.Handle("/push", pushChain)
http.Handle("/pull", pullChain)
if err := http.ListenAndServe(":3000", nil); err != nil {
log.Fatal(err)
}
}