| // 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 ( |
| "net/http" |
| "time" |
| |
| "github.com/prometheus/client_golang/prometheus" |
| ) |
| |
| // The RoundTripperFunc type is an adapter to allow the use of ordinary |
| // functions as RoundTrippers. If f is a function with the appropriate |
| // signature, RountTripperFunc(f) is a RoundTripper that calls f. |
| type RoundTripperFunc func(req *http.Request) (*http.Response, error) |
| |
| // RoundTrip implements the RoundTripper interface. |
| func (rt RoundTripperFunc) RoundTrip(r *http.Request) (*http.Response, error) { |
| return rt(r) |
| } |
| |
| // InstrumentRoundTripperInFlight is a middleware that wraps the provided |
| // http.RoundTripper. It sets the provided prometheus.Gauge to the number of |
| // requests currently handled by the wrapped http.RoundTripper. |
| // |
| // See the example for ExampleInstrumentRoundTripperDuration for example usage. |
| func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripper) RoundTripperFunc { |
| return RoundTripperFunc(func(r *http.Request) (*http.Response, error) { |
| gauge.Inc() |
| defer gauge.Dec() |
| return next.RoundTrip(r) |
| }) |
| } |
| |
| // InstrumentRoundTripperCounter is a middleware that wraps the provided |
| // 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 |
| // 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 { |
| 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() |
| } |
| return resp, err |
| }) |
| } |
| |
| // InstrumentRoundTripperDuration is a middleware that wraps the provided |
| // 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 |
| // 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 RoundTripper panics or returns a non-nil error, no values are |
| // reported. |
| // |
| // 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 { |
| 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()) |
| } |
| return resp, err |
| }) |
| } |