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promhttp: Check validity of method and code label values (#962)
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* 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]>
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kakkoyun authored Jan 18, 2022
1 parent 22da949 commit 9075cdf
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Showing 5 changed files with 319 additions and 32 deletions.
28 changes: 22 additions & 6 deletions prometheus/promhttp/instrument_client.go
View file
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.extraMethods...)).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.extraMethods...)).Observe(time.Since(start).Seconds())
}
return resp, err
})
Expand Down
111 changes: 85 additions & 26 deletions prometheus/promhttp/instrument_server.go
View file
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.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())
})
}

// 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.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()
})
}

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
// 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.extraMethods...)).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.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))
})
}

// 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.extraMethods...)).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, extraMethods ...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, extraMethods...)
}

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 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"
Expand All @@ -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"
Expand Down Expand Up @@ -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"
}
}
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