README
¶
Breaker
Breaker is a middleware for Fox that rejects requests to a failing route, using the adaptive throttling described in the Google SRE book.
Disclaimer
The current API is not yet stabilized. Breaking changes may occur before v1.0.0 and will be noted on the release note.
Getting started
Installation
go get -u github.com/fox-toolkit/breaker
Feature
- One state per route, no lock on the request path and no allocation.
- Configurable failure ratio, window, cap and minimum number of requests.
- Configurable failure definition and rejection response.
Usage
package main
import (
"errors"
"log"
"net/http"
"net/http/httputil"
"net/url"
"github.com/fox-toolkit/breaker"
"github.com/fox-toolkit/fox"
)
func main() {
mw, err := breaker.Middleware(breaker.WithFailureRatio(0.3))
if err != nil {
log.Fatalln(err)
}
f := fox.MustRouter(fox.WithMiddleware(mw))
target, _ := url.Parse("http://127.0.0.1:8081")
f.MustAdd(fox.MethodAny, "/api/*{any}", fox.WrapH(httputil.NewSingleHostReverseProxy(target)))
if err := http.ListenAndServe(":8080", f); err != nil && !errors.Is(err, http.ErrServerClosed) {
log.Fatalln(err)
}
}
Documentation
¶
Index ¶
Constants ¶
const ( // DefaultFailureRatio is the default failure ratio above which requests are rejected. DefaultFailureRatio = 0.5 // DefaultMinRequests is the default number of requests in the window below which no request is rejected. DefaultMinRequests = 20 // DefaultWindow is the default duration of the measurement window. DefaultWindow = 10 * time.Second // DefaultMaxRejectRatio is the default maximum ratio of rejected requests. DefaultMaxRejectRatio = 0.9 )
Variables ¶
var ErrInvalidConfig = errors.New("invalid config")
Functions ¶
func DefaultFailure ¶
DefaultFailure reports a response status of 500 or above as a failure.
func DefaultReject ¶
DefaultReject responds with 503 Service Unavailable.
func Middleware ¶
func Middleware(opts ...Option) (fox.MiddlewareFunc, error)
Middleware returns a fox.MiddlewareFunc that probabilistically rejects requests when the failure ratio goes above the configured ratio, based on the adaptive throttling described in the Google SRE book. Each route gets its own instance of a given breaker. One instance can reject requests while another does not, their state is not shared.
Types ¶
type Option ¶
type Option interface {
// contains filtered or unexported methods
}
Option configures the middleware.
func WithFailure ¶
WithFailure sets the function that reports whether a handled request failed. The default is DefaultFailure.
func WithFailureRatio ¶
WithFailureRatio sets the failure ratio, in [0, 1), above which requests start to be rejected. The default is DefaultFailureRatio.
func WithMaxRejectRatio ¶
WithMaxRejectRatio sets the maximum ratio, in (0, 1], of rejected requests. The remaining requests always reach the handler, which lets the middleware detect a recovery. The default is DefaultMaxRejectRatio.
func WithMinRequests ¶
WithMinRequests sets the number of requests in the window below which no request is rejected. The default is DefaultMinRequests.
func WithRejectHandler ¶
func WithRejectHandler(handler fox.HandlerFunc) Option
WithRejectHandler sets the handler called for rejected requests. The default is DefaultReject.
func WithWindow ¶
WithWindow sets the duration of the measurement window, between 1s and 10m. The default is DefaultWindow.
Source Files