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promhttp: implement WithXFromContext in terms of WithXFromRequest #1863

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promhttp: implement WithXFromContext in terms of WithXFromRequest #1863

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12 changes: 6 additions & 6 deletions prometheus/promhttp/instrument_client.go
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Original file line number Diff line number Diff line change
Expand Up @@ -75,10 +75,10 @@ func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.Rou
resp, err := next.RoundTrip(r)
if err == nil {
l := labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)
for label, resolve := range rtOpts.extraLabelsFromCtx {
l[label] = resolve(resp.Request.Context())
for label, resolve := range rtOpts.extraLabelsFromRequest {
l[label] = resolve(resp.Request)
}
addWithExemplar(counter.With(l), 1, rtOpts.getExemplarFn(r.Context()))
addWithExemplar(counter.With(l), 1, rtOpts.getExemplarFn(r))
}
return resp, err
}
Expand Down Expand Up @@ -119,10 +119,10 @@ func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundT
resp, err := next.RoundTrip(r)
if err == nil {
l := labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)
for label, resolve := range rtOpts.extraLabelsFromCtx {
l[label] = resolve(resp.Request.Context())
for label, resolve := range rtOpts.extraLabelsFromRequest {
l[label] = resolve(resp.Request)
}
observeWithExemplar(obs.With(l), time.Since(start).Seconds(), rtOpts.getExemplarFn(r.Context()))
observeWithExemplar(obs.With(l), time.Since(start).Seconds(), rtOpts.getExemplarFn(r))
}
return resp, err
}
Expand Down
48 changes: 24 additions & 24 deletions prometheus/promhttp/instrument_server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -97,21 +97,21 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler, op
next.ServeHTTP(d, r)

l := labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
observeWithExemplar(obs.With(l), time.Since(now).Seconds(), hOpts.getExemplarFn(r.Context()))
observeWithExemplar(obs.With(l), time.Since(now).Seconds(), hOpts.getExemplarFn(r))
}
}

return func(w http.ResponseWriter, r *http.Request) {
now := time.Now()
next.ServeHTTP(w, r)
l := labels(code, method, r.Method, 0, hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
observeWithExemplar(obs.With(l), time.Since(now).Seconds(), hOpts.getExemplarFn(r.Context()))
observeWithExemplar(obs.With(l), time.Since(now).Seconds(), hOpts.getExemplarFn(r))
}
}

Expand Down Expand Up @@ -147,21 +147,21 @@ func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler,
next.ServeHTTP(d, r)

l := labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
addWithExemplar(counter.With(l), 1, hOpts.getExemplarFn(r.Context()))
addWithExemplar(counter.With(l), 1, hOpts.getExemplarFn(r))
}
}

return func(w http.ResponseWriter, r *http.Request) {
next.ServeHTTP(w, r)

l := labels(code, method, r.Method, 0, hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
addWithExemplar(counter.With(l), 1, hOpts.getExemplarFn(r.Context()))
addWithExemplar(counter.With(l), 1, hOpts.getExemplarFn(r))
}
}

Expand Down Expand Up @@ -200,10 +200,10 @@ func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Ha
now := time.Now()
d := newDelegator(w, func(status int) {
l := labels(code, method, r.Method, status, hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
observeWithExemplar(obs.With(l), time.Since(now).Seconds(), hOpts.getExemplarFn(r.Context()))
observeWithExemplar(obs.With(l), time.Since(now).Seconds(), hOpts.getExemplarFn(r))
})
next.ServeHTTP(d, r)
}
Expand Down Expand Up @@ -244,10 +244,10 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler,
size := computeApproximateRequestSize(r)

l := labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
observeWithExemplar(obs.With(l), float64(size), hOpts.getExemplarFn(r.Context()))
observeWithExemplar(obs.With(l), float64(size), hOpts.getExemplarFn(r))
}
}

Expand All @@ -256,10 +256,10 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler,
size := computeApproximateRequestSize(r)

l := labels(code, method, r.Method, 0, hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
observeWithExemplar(obs.With(l), float64(size), hOpts.getExemplarFn(r.Context()))
observeWithExemplar(obs.With(l), float64(size), hOpts.getExemplarFn(r))
}
}

Expand Down Expand Up @@ -296,10 +296,10 @@ func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler
next.ServeHTTP(d, r)

l := labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)
for label, resolve := range hOpts.extraLabelsFromCtx {
l[label] = resolve(r.Context())
for label, resolve := range hOpts.extraLabelsFromRequest {
l[label] = resolve(r)
}
observeWithExemplar(obs.With(l), float64(d.Written()), hOpts.getExemplarFn(r.Context()))
observeWithExemplar(obs.With(l), float64(d.Written()), hOpts.getExemplarFn(r))
})
}

Expand Down
40 changes: 32 additions & 8 deletions prometheus/promhttp/option.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ package promhttp

import (
"context"
"net/http"

"github.com/prometheus/client_golang/prometheus"
)
Expand All @@ -24,28 +25,31 @@ type Option interface {
apply(*options)
}

// LabelValueFromRequest is used to compute the label value from request.
type LabelValueFromRequest func(request *http.Request) string

// LabelValueFromCtx are used to compute the label value from request context.
// Context can be filled with values from request through middleware.
type LabelValueFromCtx func(ctx context.Context) string

// options store options for both a handler or round tripper.
type options struct {
extraMethods []string
getExemplarFn func(requestCtx context.Context) prometheus.Labels
extraLabelsFromCtx map[string]LabelValueFromCtx
extraMethods []string
getExemplarFn func(req *http.Request) prometheus.Labels
extraLabelsFromRequest map[string]LabelValueFromRequest
}

func defaultOptions() *options {
return &options{
getExemplarFn: func(ctx context.Context) prometheus.Labels { return nil },
extraLabelsFromCtx: map[string]LabelValueFromCtx{},
getExemplarFn: func(req *http.Request) prometheus.Labels { return nil },
extraLabelsFromRequest: map[string]LabelValueFromRequest{},
}
}

func (o *options) emptyDynamicLabels() prometheus.Labels {
labels := prometheus.Labels{}

for label := range o.extraLabelsFromCtx {
for label := range o.extraLabelsFromRequest {
labels[label] = ""
}

Expand All @@ -66,19 +70,39 @@ func WithExtraMethods(methods ...string) Option {
})
}

// WithExemplarFromRequest allows to inject function that will get exemplar from request that will be put to counter and histogram metrics.
// If the function returns nil labels or the metric does not support exemplars, no exemplar will be added (noop), but
// metric will continue to observe/increment.
func WithExemplarFromRequest(getExemplarFn func(req *http.Request) prometheus.Labels) Option {
return optionApplyFunc(func(o *options) {
o.getExemplarFn = getExemplarFn
})
}

// WithExemplarFromContext allows to inject function that will get exemplar from context that will be put to counter and histogram metrics.
// If the function returns nil labels or the metric does not support exemplars, no exemplar will be added (noop), but
// metric will continue to observe/increment.
func WithExemplarFromContext(getExemplarFn func(requestCtx context.Context) prometheus.Labels) Option {
return optionApplyFunc(func(o *options) {
o.getExemplarFn = getExemplarFn
o.getExemplarFn = func(req *http.Request) prometheus.Labels {
return getExemplarFn(req.Context())
}
})
}

// WithLabelFromRequest registers a label for dynamic resolution with access to the request.
func WithLabelFromRequest(name string, valueFn LabelValueFromRequest) Option {
return optionApplyFunc(func(o *options) {
o.extraLabelsFromRequest[name] = valueFn
})
}

// WithLabelFromCtx registers a label for dynamic resolution with access to context.
// See the example for ExampleInstrumentHandlerWithLabelResolver for example usage
func WithLabelFromCtx(name string, valueFn LabelValueFromCtx) Option {
return optionApplyFunc(func(o *options) {
o.extraLabelsFromCtx[name] = valueFn
o.extraLabelsFromRequest[name] = func(req *http.Request) string {
return valueFn(req.Context())
}
})
}
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