package httpsnoop

import "github.com/felixge/httpsnoop"

Package httpsnoop provides an easy way to capture http related metrics (i.e. response time, bytes written, and http status code) from your application's http.Handlers.

Doing this requires non-trivial wrapping of the http.ResponseWriter interface, which is also exposed for users interested in a more low-level API.

Index ¶

• func Unwrap(w http.ResponseWriter) http.ResponseWriter
• func Wrap(w http.ResponseWriter, hooks Hooks) http.ResponseWriter
• type CloseNotifyFunc
• type FlushFunc
• type HeaderFunc
• type HijackFunc
• type Hooks
• type Metrics
• func CaptureMetrics(hnd http.Handler, w http.ResponseWriter, r *http.Request) Metrics
• func CaptureMetricsFn(w http.ResponseWriter, fn func(http.ResponseWriter)) Metrics
• func (m *Metrics) CaptureMetrics(w http.ResponseWriter, fn func(http.ResponseWriter))
• type PushFunc
• type ReadFromFunc
• type Unwrapper
• type WriteFunc
• type WriteHeaderFunc

Functions ¶

func Unwrap ¶

func Unwrap(w http.ResponseWriter) http.ResponseWriter

Unwrap returns the underlying http.ResponseWriter from within zero or more layers of httpsnoop wrappers.

func Wrap ¶

func Wrap(w http.ResponseWriter, hooks Hooks) http.ResponseWriter

Wrap returns a wrapped version of w that provides the exact same interface as w. Specifically if w implements any combination of:

- http.Flusher - http.CloseNotifier - http.Hijacker - io.ReaderFrom - http.Pusher

The wrapped version will implement the exact same combination. If no hooks are set, the wrapped version also behaves exactly as w. Hooks targeting methods not supported by w are ignored. Any other hooks will intercept the method they target and may modify the call's arguments and/or return values. The CaptureMetrics implementation serves as a working example for how the hooks can be used.

Types ¶

type CloseNotifyFunc ¶

type CloseNotifyFunc func() <-chan bool

CloseNotifyFunc is part of the http.CloseNotifier interface.

type FlushFunc ¶

type FlushFunc func()

FlushFunc is part of the http.Flusher interface.

type HeaderFunc ¶

type HeaderFunc func() http.Header

HeaderFunc is part of the http.ResponseWriter interface.

type HijackFunc ¶

type HijackFunc func() (net.Conn, *bufio.ReadWriter, error)

HijackFunc is part of the http.Hijacker interface.

type Hooks ¶

type Hooks struct {
	Header      func(HeaderFunc) HeaderFunc
	WriteHeader func(WriteHeaderFunc) WriteHeaderFunc
	Write       func(WriteFunc) WriteFunc
	Flush       func(FlushFunc) FlushFunc
	CloseNotify func(CloseNotifyFunc) CloseNotifyFunc
	Hijack      func(HijackFunc) HijackFunc
	ReadFrom    func(ReadFromFunc) ReadFromFunc
	Push        func(PushFunc) PushFunc
}

Hooks defines a set of method interceptors for methods included in http.ResponseWriter as well as some others. You can think of them as middleware for the function calls they target. See Wrap for more details.

type Metrics ¶

type Metrics struct {
	// Code is the first http response code passed to the WriteHeader func of
	// the ResponseWriter. If no such call is made, a default code of 200 is
	// assumed instead.
	Code int
	// Duration is the time it took to execute the handler.
	Duration time.Duration
	// Written is the number of bytes successfully written by the Write or
	// ReadFrom function of the ResponseWriter. ResponseWriters may also write
	// data to their underlaying connection directly (e.g. headers), but those
	// are not tracked. Therefor the number of Written bytes will usually match
	// the size of the response body.
	Written int64
}

Metrics holds metrics captured from CaptureMetrics.

func CaptureMetrics ¶

func CaptureMetrics(hnd http.Handler, w http.ResponseWriter, r *http.Request) Metrics

CaptureMetrics wraps the given hnd, executes it with the given w and r, and returns the metrics it captured from it.

func CaptureMetricsFn ¶

func CaptureMetricsFn(w http.ResponseWriter, fn func(http.ResponseWriter)) Metrics

CaptureMetricsFn wraps w and calls fn with the wrapped w and returns the resulting metrics. This is very similar to CaptureMetrics (which is just sugar on top of this func), but is a more usable interface if your application doesn't use the Go http.Handler interface.

func (*Metrics) CaptureMetrics ¶

func (m *Metrics) CaptureMetrics(w http.ResponseWriter, fn func(http.ResponseWriter))

CaptureMetrics wraps w and calls fn with the wrapped w and updates Metrics m with the resulting metrics. This is similar to CaptureMetricsFn, but allows one to customize starting Metrics object.

type PushFunc ¶

type PushFunc func(target string, opts *http.PushOptions) error

PushFunc is part of the http.Pusher interface.

type ReadFromFunc ¶

type ReadFromFunc func(src io.Reader) (int64, error)

ReadFromFunc is part of the io.ReaderFrom interface.

type Unwrapper ¶

type Unwrapper interface {
	Unwrap() http.ResponseWriter
}

type WriteFunc ¶

type WriteFunc func(b []byte) (int, error)

WriteFunc is part of the http.ResponseWriter interface.

type WriteHeaderFunc ¶

type WriteHeaderFunc func(code int)

WriteHeaderFunc is part of the http.ResponseWriter interface.

Source Files ¶

capture_metrics.go docs.go wrap_generated_gteq_1.8.go

Directories ¶