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

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merged 5 commits into from
Jan 18, 2022
Merged

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

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c74edb7
Check validity of method and code label values
kakkoyun Jan 17, 2022
db14f97
Use more flexibly functional option pattern for configuration
kakkoyun Jan 17, 2022
18b6ddb
Update documentation
kakkoyun Jan 17, 2022
0ef0275
Simplify
kakkoyun Jan 18, 2022
ff409ea
Fix inconsistent method naming
kakkoyun Jan 18, 2022
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28 changes: 22 additions & 6 deletions prometheus/promhttp/instrument_client.go
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Original file line number Diff line number Diff line change
Expand Up @@ -49,21 +49,29 @@ 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.
//
// If the wrapped RoundTripper panics or returns a non-nil error, the Counter
// 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.additionalMethods...)).Inc()
}
return resp, err
})
Expand All @@ -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
Expand All @@ -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.additionalMethods...)).Observe(time.Since(start).Seconds())
}
return resp, err
})
Expand Down
113 changes: 87 additions & 26 deletions prometheus/promhttp/instrument_server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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 {
Expand All @@ -67,22 +75,25 @@ 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.additionalMethods...)).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.additionalMethods...)).Observe(time.Since(now).Seconds())
})
}

// InstrumentHandlerCounter is a middleware that wraps the provided http.Handler
// 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.
Expand All @@ -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.additionalMethods...)).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.additionalMethods...)).Inc()
})
}

Expand All @@ -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
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// 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,
Expand All @@ -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.additionalMethods...)).Observe(time.Since(now).Seconds())
})
next.ServeHTTP(d, r)
})
Expand All @@ -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
Expand All @@ -156,31 +183,39 @@ 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 {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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.additionalMethods...)).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.additionalMethods...)).Observe(float64(size))
})
}

// InstrumentHandlerResponseSize is a middleware that wraps the provided
// 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
Expand All @@ -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.additionalMethods...)).Observe(float64(d.Written()))
})
}

Expand Down Expand Up @@ -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, additionalMethods ...string) prometheus.Labels {
if !(code || method) {
return emptyLabels
}
Expand All @@ -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, additionalMethods...)
}

return labels
Expand Down Expand Up @@ -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 bym using additionalMethods parameter.
func sanitizeMethod(m string, additionalMethods ...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"
Expand All @@ -348,15 +394,27 @@ 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)
if len(additionalMethods) > 0 {
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for _, method := range additionalMethods {
if strings.EqualFold(m, method) {
return strings.ToLower(m)
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Can't we just use method here instead of m? It wouldn't require ToLower if we documented that additional methods are used with the same capitalization as provided (which some users might even need).

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Of course, it's an option. I just respected the previous design decisions here. Everything was the lower case before and just kept it. I'm inclined to keep the lower case behaviour and if someone requests it we can change it; it's a minor one anyways.

}
}
}
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"
Expand Down Expand Up @@ -453,6 +511,9 @@ func sanitizeCode(s int) string {
return "511"

default:
return strconv.Itoa(s)
if s >= 100 && s <= 599 {
return strconv.Itoa(s)
}
return "unknown"
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(:

}
}
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