package circuitbreaker import ( "context" "net/http" "github.com/containous/traefik/v2/pkg/config/dynamic" "github.com/containous/traefik/v2/pkg/log" "github.com/containous/traefik/v2/pkg/middlewares" "github.com/containous/traefik/v2/pkg/tracing" "github.com/opentracing/opentracing-go/ext" "github.com/vulcand/oxy/cbreaker" ) const ( typeName = "CircuitBreaker" ) type circuitBreaker struct { circuitBreaker *cbreaker.CircuitBreaker name string } // New creates a new circuit breaker middleware. func New(ctx context.Context, next http.Handler, confCircuitBreaker dynamic.CircuitBreaker, name string) (http.Handler, error) { expression := confCircuitBreaker.Expression logger := log.FromContext(middlewares.GetLoggerCtx(ctx, name, typeName)) logger.Debug("Creating middleware") logger.Debug("Setting up with expression: %s", expression) oxyCircuitBreaker, err := cbreaker.New(next, expression, createCircuitBreakerOptions(expression)) if err != nil { return nil, err } return &circuitBreaker{ circuitBreaker: oxyCircuitBreaker, name: name, }, nil } // NewCircuitBreakerOptions returns a new CircuitBreakerOption func createCircuitBreakerOptions(expression string) cbreaker.CircuitBreakerOption { return cbreaker.Fallback(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) { tracing.SetErrorWithEvent(req, "blocked by circuit-breaker (%q)", expression) rw.WriteHeader(http.StatusServiceUnavailable) if _, err := rw.Write([]byte(http.StatusText(http.StatusServiceUnavailable))); err != nil { log.FromContext(req.Context()).Error(err) } })) } func (c *circuitBreaker) GetTracingInformation() (string, ext.SpanKindEnum) { return c.name, tracing.SpanKindNoneEnum } func (c *circuitBreaker) ServeHTTP(rw http.ResponseWriter, req *http.Request) { c.circuitBreaker.ServeHTTP(rw, req) }