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promhttp: Check validity of method and code label values (#962) 

* Check validity of method and code label values

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Use more flexibly functional option pattern for configuration

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Update documentation

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Simplify

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Fix inconsistent method naming

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>
This commit is contained in:
Kemal Akkoyun 2022-01-18 10:19:28 +01:00 committed by GitHub
parent 22da9497b8
commit 9075cdf616
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 319 additions and 32 deletions
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28
prometheus/promhttp/instrument_client.go
View File

@ -49,7 +49,10 @@ func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripp
// http.RoundTripper to observe the request result with the provided CounterVec.
// The CounterVec must have zero, one, or two non-const non-curried labels. For
// those, the only allowed label names are "code" and "method". The function
// panics otherwise. Partitioning of the CounterVec happens by HTTP status code
// panics otherwise. For the "method" label a predefined default label value set
// is used to filter given values. Values besides predefined values will count
// as `unknown` method.`WithExtraMethods` can be used to add more
// methods to the set. Partitioning of the CounterVec happens by HTTP status code
// and/or HTTP method if the respective instance label names are present in the
// CounterVec. For unpartitioned counting, use a CounterVec with zero labels.
//
@ -57,13 +60,18 @@ func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripp
// is not incremented.
//
// See the example for ExampleInstrumentRoundTripperDuration for example usage.
func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.RoundTripper) RoundTripperFunc {
func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.RoundTripper, opts ...Option) RoundTripperFunc {
rtOpts := &option{}
for _, o := range opts {
o(rtOpts)
}
code, method := checkLabels(counter)
return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
resp, err := next.RoundTrip(r)
if err == nil {
counter.With(labels(code, method, r.Method, resp.StatusCode)).Inc()
counter.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)).Inc()
}
return resp, err
})
@ -73,7 +81,10 @@ func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.Rou
// http.RoundTripper to observe the request duration with the provided
// ObserverVec. The ObserverVec must have zero, one, or two non-const
// non-curried labels. For those, the only allowed label names are "code" and
// "method". The function panics otherwise. The Observe method of the Observer
// "method". The function panics otherwise. For the "method" label a predefined
// default label value set is used to filter given values. Values besides
// predefined values will count as `unknown` method. `WithExtraMethods`
// can be used to add more methods to the set. The Observe method of the Observer
// in the ObserverVec is called with the request duration in
// seconds. Partitioning happens by HTTP status code and/or HTTP method if the
// respective instance label names are present in the ObserverVec. For
@ -85,14 +96,19 @@ func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.Rou
//
// Note that this method is only guaranteed to never observe negative durations
// if used with Go1.9+.
func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundTripper) RoundTripperFunc {
func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundTripper, opts ...Option) RoundTripperFunc {
rtOpts := &option{}
for _, o := range opts {
o(rtOpts)
}
code, method := checkLabels(obs)
return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
start := time.Now()
resp, err := next.RoundTrip(r)
if err == nil {
obs.With(labels(code, method, r.Method, resp.StatusCode)).Observe(time.Since(start).Seconds())
obs.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)).Observe(time.Since(start).Seconds())
}
return resp, err
})

111
prometheus/promhttp/instrument_server.go
View File

@ -45,7 +45,10 @@ func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handl
// http.Handler to observe the request duration with the provided ObserverVec.
// The ObserverVec must have valid metric and label names and must have zero,
// one, or two non-const non-curried labels. For those, the only allowed label
// names are "code" and "method". The function panics otherwise. The Observe
// names are "code" and "method". The function panics otherwise. For the "method"
// label a predefined default label value set is used to filter given values.
// Values besides predefined values will count as `unknown` method.
//`WithExtraMethods` can be used to add more methods to the set. The Observe
// method of the Observer in the ObserverVec is called with the request duration
// in seconds. Partitioning happens by HTTP status code and/or HTTP method if
// the respective instance label names are present in the ObserverVec. For
@ -58,7 +61,12 @@ func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handl
//
// Note that this method is only guaranteed to never observe negative durations
// if used with Go1.9+.
func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
mwOpts := &option{}
for _, o := range opts {
o(mwOpts)
}
code, method := checkLabels(obs)
if code {
@ -67,14 +75,14 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) ht
d := newDelegator(w, nil)
next.ServeHTTP(d, r)
obs.With(labels(code, method, r.Method, d.Status())).Observe(time.Since(now).Seconds())
obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
})
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
now := time.Now()
next.ServeHTTP(w, r)
obs.With(labels(code, method, r.Method, 0)).Observe(time.Since(now).Seconds())
obs.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
})
}
@ -82,7 +90,10 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) ht
// to observe the request result with the provided CounterVec. The CounterVec
// must have valid metric and label names and must have zero, one, or two
// non-const non-curried labels. For those, the only allowed label names are
// "code" and "method". The function panics otherwise. Partitioning of the
// "code" and "method". The function panics otherwise. For the "method"
// label a predefined default label value set is used to filter given values.
// Values besides predefined values will count as `unknown` method.
// `WithExtraMethods` can be used to add more methods to the set. Partitioning of the
// CounterVec happens by HTTP status code and/or HTTP method if the respective
// instance label names are present in the CounterVec. For unpartitioned
// counting, use a CounterVec with zero labels.
@ -92,20 +103,25 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) ht
// If the wrapped Handler panics, the Counter is not incremented.
//
// See the example for InstrumentHandlerDuration for example usage.
func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler) http.HandlerFunc {
func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler, opts ...Option) http.HandlerFunc {
mwOpts := &option{}
for _, o := range opts {
o(mwOpts)
}
code, method := checkLabels(counter)
if code {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
d := newDelegator(w, nil)
next.ServeHTTP(d, r)
counter.With(labels(code, method, r.Method, d.Status())).Inc()
counter.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Inc()
})
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
next.ServeHTTP(w, r)
counter.With(labels(code, method, r.Method, 0)).Inc()
counter.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Inc()
})
}
@ -114,7 +130,10 @@ func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler)
// until the response headers are written. The ObserverVec must have valid
// metric and label names and must have zero, one, or two non-const non-curried
// labels. For those, the only allowed label names are "code" and "method". The
// function panics otherwise. The Observe method of the Observer in the
// function panics otherwise. For the "method" label a predefined default label
// value set is used to filter given values. Values besides predefined values
// will count as `unknown` method.`WithExtraMethods` can be used to add more
// methods to the set. The Observe method of the Observer in the
// ObserverVec is called with the request duration in seconds. Partitioning
// happens by HTTP status code and/or HTTP method if the respective instance
// label names are present in the ObserverVec. For unpartitioned observations,
@ -128,13 +147,18 @@ func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler)
// if used with Go1.9+.
//
// See the example for InstrumentHandlerDuration for example usage.
func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
mwOpts := &option{}
for _, o := range opts {
o(mwOpts)
}
code, method := checkLabels(obs)
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
now := time.Now()
d := newDelegator(w, func(status int) {
obs.With(labels(code, method, r.Method, status)).Observe(time.Since(now).Seconds())
obs.With(labels(code, method, r.Method, status, mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
})
next.ServeHTTP(d, r)
})
@ -144,8 +168,11 @@ func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Ha
// http.Handler to observe the request size with the provided ObserverVec. The
// ObserverVec must have valid metric and label names and must have zero, one,
// or two non-const non-curried labels. For those, the only allowed label names
// are "code" and "method". The function panics otherwise. The Observe method of
// the Observer in the ObserverVec is called with the request size in
// are "code" and "method". The function panics otherwise. For the "method"
// label a predefined default label value set is used to filter given values.
// Values besides predefined values will count as `unknown` method.
// `WithExtraMethods` can be used to add more methods to the set. The Observe
// method of the Observer in the ObserverVec is called with the request size in
// bytes. Partitioning happens by HTTP status code and/or HTTP method if the
// respective instance label names are present in the ObserverVec. For
// unpartitioned observations, use an ObserverVec with zero labels. Note that
@ -156,7 +183,12 @@ func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Ha
// If the wrapped Handler panics, no values are reported.
//
// See the example for InstrumentHandlerDuration for example usage.
func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
mwOpts := &option{}
for _, o := range opts {
o(mwOpts)
}
code, method := checkLabels(obs)
if code {
@ -164,14 +196,14 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler)
d := newDelegator(w, nil)
next.ServeHTTP(d, r)
size := computeApproximateRequestSize(r)
obs.With(labels(code, method, r.Method, d.Status())).Observe(float64(size))
obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(float64(size))
})
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
next.ServeHTTP(w, r)
size := computeApproximateRequestSize(r)
obs.With(labels(code, method, r.Method, 0)).Observe(float64(size))
obs.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Observe(float64(size))
})
}
@ -179,8 +211,11 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler)
// http.Handler to observe the response size with the provided ObserverVec. The
// ObserverVec must have valid metric and label names and must have zero, one,
// or two non-const non-curried labels. For those, the only allowed label names
// are "code" and "method". The function panics otherwise. The Observe method of
// the Observer in the ObserverVec is called with the response size in
// are "code" and "method". The function panics otherwise. For the "method"
// label a predefined default label value set is used to filter given values.
// Values besides predefined values will count as `unknown` method.
// `WithExtraMethods` can be used to add more methods to the set. The Observe
// method of the Observer in the ObserverVec is called with the response size in
// bytes. Partitioning happens by HTTP status code and/or HTTP method if the
// respective instance label names are present in the ObserverVec. For
// unpartitioned observations, use an ObserverVec with zero labels. Note that
@ -191,12 +226,18 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler)
// If the wrapped Handler panics, no values are reported.
//
// See the example for InstrumentHandlerDuration for example usage.
func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler) http.Handler {
func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.Handler {
mwOpts := &option{}
for _, o := range opts {
o(mwOpts)
}
code, method := checkLabels(obs)
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
d := newDelegator(w, nil)
next.ServeHTTP(d, r)
obs.With(labels(code, method, r.Method, d.Status())).Observe(float64(d.Written()))
obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(float64(d.Written()))
})
}
@ -290,7 +331,7 @@ func isLabelCurried(c prometheus.Collector, label string) bool {
// unnecessary allocations on each request.
var emptyLabels = prometheus.Labels{}
func labels(code, method bool, reqMethod string, status int) prometheus.Labels {
func labels(code, method bool, reqMethod string, status int, extraMethods ...string) prometheus.Labels {
if !(code || method) {
return emptyLabels
}
@ -300,7 +341,7 @@ func labels(code, method bool, reqMethod string, status int) prometheus.Labels {
labels["code"] = sanitizeCode(status)
}
if method {
labels["method"] = sanitizeMethod(reqMethod)
labels["method"] = sanitizeMethod(reqMethod, extraMethods...)
}
return labels
@ -330,7 +371,12 @@ func computeApproximateRequestSize(r *http.Request) int {
return s
}
func sanitizeMethod(m string) string {
// If the wrapped http.Handler has a known method, it will be sanitized and returned.
// Otherwise, "unknown" will be returned. The known method list can be extended
// as needed by using extraMethods parameter.
func sanitizeMethod(m string, extraMethods ...string) string {
// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods for
// the methods chosen as default.
switch m {
case "GET", "get":
return "get"
@ -348,15 +394,25 @@ func sanitizeMethod(m string) string {
return "options"
case "NOTIFY", "notify":
return "notify"
case "TRACE", "trace":
return "trace"
case "PATCH", "patch":
return "patch"
default:
return strings.ToLower(m)
for _, method := range extraMethods {
if strings.EqualFold(m, method) {
return strings.ToLower(m)
}
}
return "unknown"
}
}
// If the wrapped http.Handler has not set a status code, i.e. the value is
// currently 0, santizeCode will return 200, for consistency with behavior in
// currently 0, sanitizeCode will return 200, for consistency with behavior in
// the stdlib.
func sanitizeCode(s int) string {
// See for accepted codes https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
switch s {
case 100:
return "100"
@ -453,6 +509,9 @@ func sanitizeCode(s int) string {
return "511"
default:
return strconv.Itoa(s)
if s >= 100 && s <= 599 {
return strconv.Itoa(s)
}
return "unknown"
}
}

116
prometheus/promhttp/instrument_server_test.go
View File

@ -204,6 +204,122 @@ func TestLabelCheck(t *testing.T) {
}
}
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 bool, 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 TestMiddlewareAPI(t *testing.T) {
reg := prometheus.NewRegistry()

31
prometheus/promhttp/option.go Normal file
View File

@ -0,0 +1,31 @@
// Copyright 2022 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
// Option are used to configure a middleware or round tripper..
type Option func(*option)
type option struct {
extraMethods []string
}
// WithExtraMethods adds additional HTTP methods to the list of allowed methods.
// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods for the default list.
//
// See the example for ExampleInstrumentHandlerWithExtraMethods for example usage.
func WithExtraMethods(methods ...string) Option {
return func(o *option) {
o.extraMethods = methods
}
}

65
prometheus/promhttp/option_test.go Normal file
View File

@ -0,0 +1,65 @@
// Copyright 2022 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 (
"log"
"net/http"
"github.com/prometheus/client_golang/prometheus"
)
func ExampleInstrumentHandlerWithExtraMethods() {
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"},
)
// Create the handlers that will be wrapped by the middleware.
pullHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("Pull"))
})
// Specify additional HTTP methods to be added to the label allow list.
opts := WithExtraMethods("CUSTOM_METHOD")
// Instrument the handlers with all the metrics, injecting the "handler"
// label by currying.
pullChain :=
InstrumentHandlerDuration(duration.MustCurryWith(prometheus.Labels{"handler": "pull"}),
InstrumentHandlerCounter(counter, pullHandler, opts),
opts,
)
http.Handle("/metrics", Handler())
http.Handle("/pull", pullChain)
if err := http.ListenAndServe(":3000", nil); err != nil {
log.Fatal(err)
}
}