add yaml config for retry()

Signed-off-by: Sandor Szücs <[email protected]>

filters/retry/retry.go

@@ -1,18 +1,82 @@
 package retry
 
 import (
+	"fmt"
+	"net/http"
+
 	"github.com/zalando/skipper/filters"
+	"gopkg.in/yaml.v2"
+)
+
+const (
+	single = "single"
 )
 
-type retry struct{}
+type (
+	retrySpec   struct{}
+	RetryFilter struct {
+		Type        string `json:"type,omitempty"`
+		StatusCodes []int  `json:"status-codes,omitempty"`
+		MaxTimes    int    `json:"max-times,omitempty"`
+
+		Check func(*http.Response) bool
+	}
+)
 
 // NewRetry creates a filter specification for the retry() filter
-func NewRetry() filters.Spec { return retry{} }
+func NewRetry() filters.Spec { return &retrySpec{} }
+
+func (*retrySpec) Name() string { return filters.RetryName }
+
+func (s *retrySpec) CreateFilter(args []interface{}) (filters.Filter, error) {
+	rf := &RetryFilter{}
+
+	if config, ok := args[0].(string); !ok {
+		return nil, fmt.Errorf("filter %q requires single string argument", s.Name())
+	} else if err := yaml.Unmarshal([]byte(config), rf); err != nil {
+		return nil, fmt.Errorf("failed to parse configuration: %w", err)
+	}
+
+	switch rf.Type {
+	case single:
+		i := 0
+		rf.Check = func(rsp *http.Response) bool {
+			i++
+			if i > rf.MaxTimes {
+				return false
+			}
+			return shouldRetry(rsp.StatusCode, rf.StatusCodes)
+		}
+	}
+
+	return rf, nil
+}
+
+// copy from proxy.shouldLog
+func shouldRetry(statusCode int, prefixes []int) bool {
+	if len(prefixes) == 0 {
+		return false
+	}
+
+	match := false
+	for _, prefix := range prefixes {
+		switch {
+		case prefix < 10:
+			match = (statusCode >= prefix*100 && statusCode < (prefix+1)*100)
+		case prefix < 100:
+			match = (statusCode >= prefix*10 && statusCode < (prefix+1)*10)
+		default:
+			match = statusCode == prefix
+		}
+		if match {
+			break
+		}
+	}
+	return match
+}
 
-func (retry) Name() string                                       { return filters.RetryName }
-func (retry) CreateFilter([]interface{}) (filters.Filter, error) { return retry{}, nil }
-func (retry) Response(filters.FilterContext)                     {}
+func (rf *RetryFilter) Response(filters.FilterContext) {}
 
-func (retry) Request(ctx filters.FilterContext) {
-	ctx.StateBag()[filters.RetryName] = struct{}{}
+func (rf *RetryFilter) Request(ctx filters.FilterContext) {
+	ctx.StateBag()[filters.RetryName] = rf.Check
 }