package middlewares import ( "net/http" "strconv" "strings" "github.com/containous/traefik/log" "github.com/containous/traefik/types" "github.com/vulcand/oxy/forward" "github.com/vulcand/oxy/utils" ) //ErrorPagesHandler is a middleware that provides the custom error pages type ErrorPagesHandler struct { HTTPCodeRanges [][2]int BackendURL string errorPageForwarder *forward.Forwarder } //NewErrorPagesHandler initializes the utils.ErrorHandler for the custom error pages func NewErrorPagesHandler(errorPage *types.ErrorPage, backendURL string) (*ErrorPagesHandler, error) { fwd, err := forward.New() if err != nil { return nil, err } //Break out the http status code ranges into a low int and high int //for ease of use at runtime var blocks [][2]int for _, block := range errorPage.Status { codes := strings.Split(block, "-") //if only a single HTTP code was configured, assume the best and create the correct configuration on the user's behalf if len(codes) == 1 { codes = append(codes, codes[0]) } lowCode, err := strconv.Atoi(codes[0]) if err != nil { return nil, err } highCode, err := strconv.Atoi(codes[1]) if err != nil { return nil, err } blocks = append(blocks, [2]int{lowCode, highCode}) } return &ErrorPagesHandler{ HTTPCodeRanges: blocks, BackendURL: backendURL + errorPage.Query, errorPageForwarder: fwd}, nil } func (ep *ErrorPagesHandler) ServeHTTP(w http.ResponseWriter, req *http.Request, next http.HandlerFunc) { recorder := newRetryResponseRecorder() recorder.responseWriter = w next.ServeHTTP(recorder, req) w.WriteHeader(recorder.Code) //check the recorder code against the configured http status code ranges for _, block := range ep.HTTPCodeRanges { if recorder.Code >= block[0] && recorder.Code <= block[1] { log.Errorf("Caught HTTP Status Code %d, returning error page", recorder.Code) finalURL := strings.Replace(ep.BackendURL, "{status}", strconv.Itoa(recorder.Code), -1) if newReq, err := http.NewRequest(http.MethodGet, finalURL, nil); err != nil { w.Write([]byte(http.StatusText(recorder.Code))) } else { ep.errorPageForwarder.ServeHTTP(w, newReq) } return } } //did not catch a configured status code so proceed with the request utils.CopyHeaders(w.Header(), recorder.Header()) w.Write(recorder.Body.Bytes()) }