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promhttp: Check validity of method and code label values (#962) (#987)
* Check validity of method and code label values Signed-off-by: Kemal Akkoyun <[email protected]> * Use more flexibly functional option pattern for configuration Signed-off-by: Kemal Akkoyun <[email protected]> * Update documentation Signed-off-by: Kemal Akkoyun <[email protected]> * Simplify Signed-off-by: Kemal Akkoyun <[email protected]> * Fix inconsistent method naming Signed-off-by: Kemal Akkoyun <[email protected]> Co-authored-by: Kemal Akkoyun <[email protected]>
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-32
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5 files changed

+319
-32
lines changed

‎prometheus/promhttp/instrument_client.go‎

Lines changed: 22 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -49,21 +49,29 @@ func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripp
4949
// http.RoundTripper to observe the request result with the provided CounterVec.
5050
// The CounterVec must have zero, one, or two non-const non-curried labels. For
5151
// those, the only allowed label names are "code" and "method". The function
52-
// panics otherwise. Partitioning of the CounterVec happens by HTTP status code
52+
// panics otherwise. For the "method" label a predefined default label value set
53+
// is used to filter given values. Values besides predefined values will count
54+
// as `unknown` method.`WithExtraMethods` can be used to add more
55+
// methods to the set. Partitioning of the CounterVec happens by HTTP status code
5356
// and/or HTTP method if the respective instance label names are present in the
5457
// CounterVec. For unpartitioned counting, use a CounterVec with zero labels.
5558
//
5659
// If the wrapped RoundTripper panics or returns a non-nil error, the Counter
5760
// is not incremented.
5861
//
5962
// See the example for ExampleInstrumentRoundTripperDuration for example usage.
60-
func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.RoundTripper) RoundTripperFunc {
63+
func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.RoundTripper, opts ...Option) RoundTripperFunc {
64+
rtOpts := &option{}
65+
for _, o := range opts {
66+
o(rtOpts)
67+
}
68+
6169
code, method := checkLabels(counter)
6270

6371
return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
6472
resp, err := next.RoundTrip(r)
6573
if err == nil {
66-
counter.With(labels(code, method, r.Method, resp.StatusCode)).Inc()
74+
counter.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)).Inc()
6775
}
6876
return resp, err
6977
})
@@ -73,7 +81,10 @@ func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.Rou
7381
// http.RoundTripper to observe the request duration with the provided
7482
// ObserverVec. The ObserverVec must have zero, one, or two non-const
7583
// non-curried labels. For those, the only allowed label names are "code" and
76-
// "method". The function panics otherwise. The Observe method of the Observer
84+
// "method". The function panics otherwise. For the "method" label a predefined
85+
// default label value set is used to filter given values. Values besides
86+
// predefined values will count as `unknown` method. `WithExtraMethods`
87+
// can be used to add more methods to the set. The Observe method of the Observer
7788
// in the ObserverVec is called with the request duration in
7889
// seconds. Partitioning happens by HTTP status code and/or HTTP method if the
7990
// respective instance label names are present in the ObserverVec. For
@@ -85,14 +96,19 @@ func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.Rou
8596
//
8697
// Note that this method is only guaranteed to never observe negative durations
8798
// if used with Go1.9+.
88-
func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundTripper) RoundTripperFunc {
99+
func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundTripper, opts ...Option) RoundTripperFunc {
100+
rtOpts := &option{}
101+
for _, o := range opts {
102+
o(rtOpts)
103+
}
104+
89105
code, method := checkLabels(obs)
90106

91107
return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
92108
start := time.Now()
93109
resp, err := next.RoundTrip(r)
94110
if err == nil {
95-
obs.With(labels(code, method, r.Method, resp.StatusCode)).Observe(time.Since(start).Seconds())
111+
obs.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)).Observe(time.Since(start).Seconds())
96112
}
97113
return resp, err
98114
})

‎prometheus/promhttp/instrument_server.go‎

Lines changed: 85 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -45,7 +45,10 @@ func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handl
4545
// http.Handler to observe the request duration with the provided ObserverVec.
4646
// The ObserverVec must have valid metric and label names and must have zero,
4747
// one, or two non-const non-curried labels. For those, the only allowed label
48-
// names are "code" and "method". The function panics otherwise. The Observe
48+
// names are "code" and "method". The function panics otherwise. For the "method"
49+
// label a predefined default label value set is used to filter given values.
50+
// Values besides predefined values will count as `unknown` method.
51+
//`WithExtraMethods` can be used to add more methods to the set. The Observe
4952
// method of the Observer in the ObserverVec is called with the request duration
5053
// in seconds. Partitioning happens by HTTP status code and/or HTTP method if
5154
// 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
5861
//
5962
// Note that this method is only guaranteed to never observe negative durations
6063
// if used with Go1.9+.
61-
func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
64+
func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
65+
mwOpts := &option{}
66+
for _, o := range opts {
67+
o(mwOpts)
68+
}
69+
6270
code, method := checkLabels(obs)
6371

6472
if code {
@@ -67,22 +75,25 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) ht
6775
d := newDelegator(w, nil)
6876
next.ServeHTTP(d, r)
6977

70-
obs.With(labels(code, method, r.Method, d.Status())).Observe(time.Since(now).Seconds())
78+
obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
7179
})
7280
}
7381

7482
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
7583
now := time.Now()
7684
next.ServeHTTP(w, r)
77-
obs.With(labels(code, method, r.Method, 0)).Observe(time.Since(now).Seconds())
85+
obs.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
7886
})
7987
}
8088

8189
// InstrumentHandlerCounter is a middleware that wraps the provided http.Handler
8290
// to observe the request result with the provided CounterVec. The CounterVec
8391
// must have valid metric and label names and must have zero, one, or two
8492
// non-const non-curried labels. For those, the only allowed label names are
85-
// "code" and "method". The function panics otherwise. Partitioning of the
93+
// "code" and "method". The function panics otherwise. For the "method"
94+
// label a predefined default label value set is used to filter given values.
95+
// Values besides predefined values will count as `unknown` method.
96+
// `WithExtraMethods` can be used to add more methods to the set. Partitioning of the
8697
// CounterVec happens by HTTP status code and/or HTTP method if the respective
8798
// instance label names are present in the CounterVec. For unpartitioned
8899
// counting, use a CounterVec with zero labels.
@@ -92,20 +103,25 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) ht
92103
// If the wrapped Handler panics, the Counter is not incremented.
93104
//
94105
// See the example for InstrumentHandlerDuration for example usage.
95-
func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler) http.HandlerFunc {
106+
func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler, opts ...Option) http.HandlerFunc {
107+
mwOpts := &option{}
108+
for _, o := range opts {
109+
o(mwOpts)
110+
}
111+
96112
code, method := checkLabels(counter)
97113

98114
if code {
99115
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
100116
d := newDelegator(w, nil)
101117
next.ServeHTTP(d, r)
102-
counter.With(labels(code, method, r.Method, d.Status())).Inc()
118+
counter.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Inc()
103119
})
104120
}
105121

106122
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
107123
next.ServeHTTP(w, r)
108-
counter.With(labels(code, method, r.Method, 0)).Inc()
124+
counter.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Inc()
109125
})
110126
}
111127

@@ -114,7 +130,10 @@ func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler)
114130
// until the response headers are written. The ObserverVec must have valid
115131
// metric and label names and must have zero, one, or two non-const non-curried
116132
// labels. For those, the only allowed label names are "code" and "method". The
117-
// function panics otherwise. The Observe method of the Observer in the
133+
// function panics otherwise. For the "method" label a predefined default label
134+
// value set is used to filter given values. Values besides predefined values
135+
// will count as `unknown` method.`WithExtraMethods` can be used to add more
136+
// methods to the set. The Observe method of the Observer in the
118137
// ObserverVec is called with the request duration in seconds. Partitioning
119138
// happens by HTTP status code and/or HTTP method if the respective instance
120139
// label names are present in the ObserverVec. For unpartitioned observations,
@@ -128,13 +147,18 @@ func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler)
128147
// if used with Go1.9+.
129148
//
130149
// See the example for InstrumentHandlerDuration for example usage.
131-
func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
150+
func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
151+
mwOpts := &option{}
152+
for _, o := range opts {
153+
o(mwOpts)
154+
}
155+
132156
code, method := checkLabels(obs)
133157

134158
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
135159
now := time.Now()
136160
d := newDelegator(w, func(status int) {
137-
obs.With(labels(code, method, r.Method, status)).Observe(time.Since(now).Seconds())
161+
obs.With(labels(code, method, r.Method, status, mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
138162
})
139163
next.ServeHTTP(d, r)
140164
})
@@ -144,8 +168,11 @@ func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Ha
144168
// http.Handler to observe the request size with the provided ObserverVec. The
145169
// ObserverVec must have valid metric and label names and must have zero, one,
146170
// or two non-const non-curried labels. For those, the only allowed label names
147-
// are "code" and "method". The function panics otherwise. The Observe method of
148-
// the Observer in the ObserverVec is called with the request size in
171+
// are "code" and "method". The function panics otherwise. For the "method"
172+
// label a predefined default label value set is used to filter given values.
173+
// Values besides predefined values will count as `unknown` method.
174+
// `WithExtraMethods` can be used to add more methods to the set. The Observe
175+
// method of the Observer in the ObserverVec is called with the request size in
149176
// bytes. Partitioning happens by HTTP status code and/or HTTP method if the
150177
// respective instance label names are present in the ObserverVec. For
151178
// unpartitioned observations, use an ObserverVec with zero labels. Note that
@@ -156,31 +183,39 @@ func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Ha
156183
// If the wrapped Handler panics, no values are reported.
157184
//
158185
// See the example for InstrumentHandlerDuration for example usage.
159-
func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
186+
func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
187+
mwOpts := &option{}
188+
for _, o := range opts {
189+
o(mwOpts)
190+
}
191+
160192
code, method := checkLabels(obs)
161193

162194
if code {
163195
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
164196
d := newDelegator(w, nil)
165197
next.ServeHTTP(d, r)
166198
size := computeApproximateRequestSize(r)
167-
obs.With(labels(code, method, r.Method, d.Status())).Observe(float64(size))
199+
obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(float64(size))
168200
})
169201
}
170202

171203
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
172204
next.ServeHTTP(w, r)
173205
size := computeApproximateRequestSize(r)
174-
obs.With(labels(code, method, r.Method, 0)).Observe(float64(size))
206+
obs.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Observe(float64(size))
175207
})
176208
}
177209

178210
// InstrumentHandlerResponseSize is a middleware that wraps the provided
179211
// http.Handler to observe the response size with the provided ObserverVec. The
180212
// ObserverVec must have valid metric and label names and must have zero, one,
181213
// or two non-const non-curried labels. For those, the only allowed label names
182-
// are "code" and "method". The function panics otherwise. The Observe method of
183-
// the Observer in the ObserverVec is called with the response size in
214+
// are "code" and "method". The function panics otherwise. For the "method"
215+
// label a predefined default label value set is used to filter given values.
216+
// Values besides predefined values will count as `unknown` method.
217+
// `WithExtraMethods` can be used to add more methods to the set. The Observe
218+
// method of the Observer in the ObserverVec is called with the response size in
184219
// bytes. Partitioning happens by HTTP status code and/or HTTP method if the
185220
// respective instance label names are present in the ObserverVec. For
186221
// unpartitioned observations, use an ObserverVec with zero labels. Note that
@@ -191,12 +226,18 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler)
191226
// If the wrapped Handler panics, no values are reported.
192227
//
193228
// See the example for InstrumentHandlerDuration for example usage.
194-
func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler) http.Handler {
229+
func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.Handler {
230+
mwOpts := &option{}
231+
for _, o := range opts {
232+
o(mwOpts)
233+
}
234+
195235
code, method := checkLabels(obs)
236+
196237
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
197238
d := newDelegator(w, nil)
198239
next.ServeHTTP(d, r)
199-
obs.With(labels(code, method, r.Method, d.Status())).Observe(float64(d.Written()))
240+
obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(float64(d.Written()))
200241
})
201242
}
202243

@@ -290,7 +331,7 @@ func isLabelCurried(c prometheus.Collector, label string) bool {
290331
// unnecessary allocations on each request.
291332
var emptyLabels = prometheus.Labels{}
292333

293-
func labels(code, method bool, reqMethod string, status int) prometheus.Labels {
334+
func labels(code, method bool, reqMethod string, status int, extraMethods ...string) prometheus.Labels {
294335
if !(code || method) {
295336
return emptyLabels
296337
}
@@ -300,7 +341,7 @@ func labels(code, method bool, reqMethod string, status int) prometheus.Labels {
300341
labels["code"] = sanitizeCode(status)
301342
}
302343
if method {
303-
labels["method"] = sanitizeMethod(reqMethod)
344+
labels["method"] = sanitizeMethod(reqMethod, extraMethods...)
304345
}
305346

306347
return labels
@@ -330,7 +371,12 @@ func computeApproximateRequestSize(r *http.Request) int {
330371
return s
331372
}
332373

333-
func sanitizeMethod(m string) string {
374+
// If the wrapped http.Handler has a known method, it will be sanitized and returned.
375+
// Otherwise, "unknown" will be returned. The known method list can be extended
376+
// as needed by using extraMethods parameter.
377+
func sanitizeMethod(m string, extraMethods ...string) string {
378+
// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods for
379+
// the methods chosen as default.
334380
switch m {
335381
case "GET", "get":
336382
return "get"
@@ -348,15 +394,25 @@ func sanitizeMethod(m string) string {
348394
return "options"
349395
case "NOTIFY", "notify":
350396
return "notify"
397+
case "TRACE", "trace":
398+
return "trace"
399+
case "PATCH", "patch":
400+
return "patch"
351401
default:
352-
return strings.ToLower(m)
402+
for _, method := range extraMethods {
403+
if strings.EqualFold(m, method) {
404+
return strings.ToLower(m)
405+
}
406+
}
407+
return "unknown"
353408
}
354409
}
355410

356411
// If the wrapped http.Handler has not set a status code, i.e. the value is
357-
// currently 0, santizeCode will return 200, for consistency with behavior in
412+
// currently 0, sanitizeCode will return 200, for consistency with behavior in
358413
// the stdlib.
359414
func sanitizeCode(s int) string {
415+
// See for accepted codes https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
360416
switch s {
361417
case 100:
362418
return "100"
@@ -453,6 +509,9 @@ func sanitizeCode(s int) string {
453509
return "511"
454510

455511
default:
456-
return strconv.Itoa(s)
512+
if s >= 100 && s <= 599 {
513+
return strconv.Itoa(s)
514+
}
515+
return "unknown"
457516
}
458517
}

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