Handle HTTP status codes in the HTTP breaker example

example/http_breaker.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -11,13 +12,34 @@ import (
 
 var cb *gobreaker.CircuitBreaker
 
+// StatusError is returned when the server responds with a non-2xx status code.
+type StatusError struct {
+	Code   int
+	Status string
+}
+
+func (e *StatusError) Error() string {
+	return "unexpected status: " + e.Status
+}
+
 func init() {
 	var st gobreaker.Settings
 	st.Name = "HTTP GET"
 	st.ReadyToTrip = func(counts gobreaker.Counts) bool {
 		failureRatio := float64(counts.TotalFailures) / float64(counts.Requests)
 		return counts.Requests >= 3 && failureRatio >= 0.6
 	}
+	st.IsSuccessful = func(err error) bool {
+		if err == nil {
+			return true
+		}
+		// Server errors indicate the service is unhealthy and should trip
+		// the circuit breaker. Client errors such as 404 Not Found are
+		// responses the server produced deliberately, so they are returned
+		// to the caller without counting as failures.
+		var se *StatusError
+		return errors.As(err, &se) && se.Code < http.StatusInternalServerError
+	}
 
 	cb = gobreaker.NewCircuitBreaker(st)
 }
@@ -31,6 +53,11 @@ func Get(url string) ([]byte, error) {
 		}
 
 		defer resp.Body.Close()
+
+		if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+			return nil, &StatusError{Code: resp.StatusCode, Status: resp.Status}
+		}
+
 		return ioutil.ReadAll(resp.Body)
 	})
 	if err != nil {

v2/example/http_breaker.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -11,13 +12,34 @@ import (
 
 var cb *gobreaker.CircuitBreaker[[]byte]
 
+// StatusError is returned when the server responds with a non-2xx status code.
+type StatusError struct {
+	Code   int
+	Status string
+}
+
+func (e *StatusError) Error() string {
+	return "unexpected status: " + e.Status
+}
+
 func init() {
 	var st gobreaker.Settings
 	st.Name = "HTTP GET"
 	st.ReadyToTrip = func(counts gobreaker.Counts) bool {
 		failureRatio := float64(counts.TotalFailures) / float64(counts.Requests)
 		return counts.Requests >= 3 && failureRatio >= 0.6
 	}
+	st.IsSuccessful = func(err error) bool {
+		if err == nil {
+			return true
+		}
+		// Server errors indicate the service is unhealthy and should trip
+		// the circuit breaker. Client errors such as 404 Not Found are
+		// responses the server produced deliberately, so they are returned
+		// to the caller without counting as failures.
+		var se *StatusError
+		return errors.As(err, &se) && se.Code < http.StatusInternalServerError
+	}
 
 	cb = gobreaker.NewCircuitBreaker[[]byte](st)
 }
@@ -31,6 +53,11 @@ func Get(url string) ([]byte, error) {
 		}
 
 		defer resp.Body.Close()
+
+		if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+			return nil, &StatusError{Code: resp.StatusCode, Status: resp.Status}
+		}
+
 		return io.ReadAll(resp.Body)
 	})
 	if err != nil {