diff options
Diffstat (limited to 'vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server.go')
-rw-r--r-- | vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server.go | 447 |
1 files changed, 447 insertions, 0 deletions
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server.go b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server.go new file mode 100644 index 000000000..9db243805 --- /dev/null +++ b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server.go @@ -0,0 +1,447 @@ +// Copyright 2017 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 ( + "errors" + "net/http" + "strconv" + "strings" + "time" + + dto "github.com/prometheus/client_model/go" + + "github.com/prometheus/client_golang/prometheus" +) + +// magicString is used for the hacky label test in checkLabels. Remove once fixed. +const magicString = "zZgWfBxLqvG8kc8IMv3POi2Bb0tZI3vAnBx+gBaFi9FyPzB/CzKUer1yufDa" + +// InstrumentHandlerInFlight is a middleware that wraps the provided +// http.Handler. It sets the provided prometheus.Gauge to the number of +// requests currently handled by the wrapped http.Handler. +// +// See the example for InstrumentHandlerDuration for example usage. +func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handler { + return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { + g.Inc() + defer g.Dec() + next.ServeHTTP(w, r) + }) +} + +// InstrumentHandlerDuration is a middleware that wraps the provided +// http.Handler 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 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, use an +// ObserverVec with zero labels. Note that partitioning of Histograms is +// expensive and should be used judiciously. +// +// If the wrapped Handler does not set a status code, a status code of 200 is assumed. +// +// If the wrapped Handler panics, no values are reported. +// +// 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 { + code, method := checkLabels(obs) + + if code { + return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { + now := time.Now() + d := newDelegator(w, nil) + next.ServeHTTP(d, r) + + obs.With(labels(code, method, r.Method, d.Status())).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()) + }) +} + +// InstrumentHandlerCounter is a middleware that wraps the provided http.Handler +// 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 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 Handler does not set a status code, a status code of 200 is assumed. +// +// 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 { + 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() + }) + } + + return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { + next.ServeHTTP(w, r) + counter.With(labels(code, method, r.Method, 0)).Inc() + }) +} + +// InstrumentHandlerTimeToWriteHeader is a middleware that wraps the provided +// http.Handler to observe with the provided ObserverVec the request duration +// until the response headers are written. 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 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, use an ObserverVec with zero labels. Note that +// partitioning of Histograms is expensive and should be used judiciously. +// +// If the wrapped Handler panics before calling WriteHeader, no value is +// reported. +// +// Note that this method is only guaranteed to never observe negative durations +// if used with Go1.9+. +// +// See the example for InstrumentHandlerDuration for example usage. +func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc { + 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()) + }) + next.ServeHTTP(d, r) + }) +} + +// InstrumentHandlerRequestSize is a middleware that wraps the provided +// http.Handler to observe the request size 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 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 partitioning of Histograms is expensive and should be used +// judiciously. +// +// If the wrapped Handler does not set a status code, a status code of 200 is assumed. +// +// 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 { + 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)) + }) + } + + 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)) + }) +} + +// InstrumentHandlerResponseSize is a middleware that wraps the provided +// http.Handler to observe the response size 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 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 partitioning of Histograms is expensive and should be used +// judiciously. +// +// If the wrapped Handler does not set a status code, a status code of 200 is assumed. +// +// 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 { + 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())) + }) +} + +func checkLabels(c prometheus.Collector) (code bool, method bool) { + // TODO(beorn7): Remove this hacky way to check for instance labels + // once Descriptors can have their dimensionality queried. + var ( + desc *prometheus.Desc + m prometheus.Metric + pm dto.Metric + lvs []string + ) + + // Get the Desc from the Collector. + descc := make(chan *prometheus.Desc, 1) + c.Describe(descc) + + select { + case desc = <-descc: + default: + panic("no description provided by collector") + } + select { + case <-descc: + panic("more than one description provided by collector") + default: + } + + close(descc) + + // Create a ConstMetric with the Desc. Since we don't know how many + // variable labels there are, try for as long as it needs. + for err := errors.New("dummy"); err != nil; lvs = append(lvs, magicString) { + m, err = prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0, lvs...) + } + + // Write out the metric into a proto message and look at the labels. + // If the value is not the magicString, it is a constLabel, which doesn't interest us. + // If the label is curried, it doesn't interest us. + // In all other cases, only "code" or "method" is allowed. + if err := m.Write(&pm); err != nil { + panic("error checking metric for labels") + } + for _, label := range pm.Label { + name, value := label.GetName(), label.GetValue() + if value != magicString || isLabelCurried(c, name) { + continue + } + switch name { + case "code": + code = true + case "method": + method = true + default: + panic("metric partitioned with non-supported labels") + } + } + return +} + +func isLabelCurried(c prometheus.Collector, label string) bool { + // This is even hackier than the label test above. + // We essentially try to curry again and see if it works. + // But for that, we need to type-convert to the two + // types we use here, ObserverVec or *CounterVec. + switch v := c.(type) { + case *prometheus.CounterVec: + if _, err := v.CurryWith(prometheus.Labels{label: "dummy"}); err == nil { + return false + } + case prometheus.ObserverVec: + if _, err := v.CurryWith(prometheus.Labels{label: "dummy"}); err == nil { + return false + } + default: + panic("unsupported metric vec type") + } + return true +} + +// emptyLabels is a one-time allocation for non-partitioned metrics to avoid +// unnecessary allocations on each request. +var emptyLabels = prometheus.Labels{} + +func labels(code, method bool, reqMethod string, status int) prometheus.Labels { + if !(code || method) { + return emptyLabels + } + labels := prometheus.Labels{} + + if code { + labels["code"] = sanitizeCode(status) + } + if method { + labels["method"] = sanitizeMethod(reqMethod) + } + + return labels +} + +func computeApproximateRequestSize(r *http.Request) int { + s := 0 + if r.URL != nil { + s += len(r.URL.String()) + } + + s += len(r.Method) + s += len(r.Proto) + for name, values := range r.Header { + s += len(name) + for _, value := range values { + s += len(value) + } + } + s += len(r.Host) + + // N.B. r.Form and r.MultipartForm are assumed to be included in r.URL. + + if r.ContentLength != -1 { + s += int(r.ContentLength) + } + return s +} + +func sanitizeMethod(m string) string { + switch m { + case "GET", "get": + return "get" + case "PUT", "put": + return "put" + case "HEAD", "head": + return "head" + case "POST", "post": + return "post" + case "DELETE", "delete": + return "delete" + case "CONNECT", "connect": + return "connect" + case "OPTIONS", "options": + return "options" + case "NOTIFY", "notify": + return "notify" + default: + return strings.ToLower(m) + } +} + +// 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 +// the stdlib. +func sanitizeCode(s int) string { + switch s { + case 100: + return "100" + case 101: + return "101" + + case 200, 0: + return "200" + case 201: + return "201" + case 202: + return "202" + case 203: + return "203" + case 204: + return "204" + case 205: + return "205" + case 206: + return "206" + + case 300: + return "300" + case 301: + return "301" + case 302: + return "302" + case 304: + return "304" + case 305: + return "305" + case 307: + return "307" + + case 400: + return "400" + case 401: + return "401" + case 402: + return "402" + case 403: + return "403" + case 404: + return "404" + case 405: + return "405" + case 406: + return "406" + case 407: + return "407" + case 408: + return "408" + case 409: + return "409" + case 410: + return "410" + case 411: + return "411" + case 412: + return "412" + case 413: + return "413" + case 414: + return "414" + case 415: + return "415" + case 416: + return "416" + case 417: + return "417" + case 418: + return "418" + + case 500: + return "500" + case 501: + return "501" + case 502: + return "502" + case 503: + return "503" + case 504: + return "504" + case 505: + return "505" + + case 428: + return "428" + case 429: + return "429" + case 431: + return "431" + case 511: + return "511" + + default: + return strconv.Itoa(s) + } +} |