feature: add filter that sets a span tag on response status condition (…

…#3202) * feature: add filter that sets a span tag on response status condition Signed-off-by: Sandor Szücs <sandor.szuecs@zalando.de>
zalando · Aug 21, 2024 · 2167128 · 2167128
1 parent dfeffe0
commit 2167128
Show file tree

Hide file tree

Showing 5 changed files with 301 additions and 34 deletions.
diff --git a/docs/reference/filters.md b/docs/reference/filters.md
@@ -3352,6 +3352,15 @@ tracingTag("http.flow_id", "${request.header.X-Flow-Id}")
 
 This filter works just like [tracingTag](#tracingtag), but is applied after the request was processed. In particular, [template placeholders](#template-placeholders) referencing the response can be used in the parameters.
 
+### tracingTagFromResponseIfStatus
+
+Example: set error tag to true in case response status code is `>= 500` and `<= 599`
+
+```
+tracingTagFromResponseIfStatus("error", "true", 500, 599)
+```
+
+
 ### tracingSpanName
 
 This filter sets the name of the outgoing (client span) in opentracing. The default name is "proxy". Example:

diff --git a/filters/builtin/builtin.go b/filters/builtin/builtin.go
@@ -214,6 +214,7 @@ func Filters() []filters.Spec {
 		tracing.NewBaggageToTagFilter(),
 		tracing.NewTag(),
 		tracing.NewTagFromResponse(),
+		tracing.NewTagFromResponseIfStatus(),
 		tracing.NewStateBagToTag(),
 		//lint:ignore SA1019 due to backward compatibility
 		accesslog.NewAccessLogDisabled(),

diff --git a/filters/filters.go b/filters/filters.go
@@ -351,6 +351,7 @@ const (
 	StateBagToTagName                          = "stateBagToTag"
 	TracingTagName                             = "tracingTag"
 	TracingTagFromResponseName                 = "tracingTagFromResponse"
+	TracingTagFromResponseIfStatusName         = "tracingTagFromResponseIfStatus"
 	TracingSpanNameName                        = "tracingSpanName"
 	OriginMarkerName                           = "originMarker"
 	FadeInName                                 = "fadeIn"

diff --git a/filters/tracing/tag.go b/filters/tracing/tag.go
@@ -1,6 +1,8 @@
 package tracing
 
 import (
+	"net/http"
+
 	opentracing "github.com/opentracing/opentracing-go"
 	"github.com/zalando/skipper/eskip"
 	"github.com/zalando/skipper/filters"
@@ -10,11 +12,21 @@ type tagSpec struct {
 	typ string
 }
 
+type tagFilterType int
+
+const (
+	tagRequest tagFilterType = iota + 1
+	tagResponse
+	tagResponseCondition
+)
+
 type tagFilter struct {
-	tagFromResponse bool
+	typ tagFilterType
 
 	tagName  string
 	tagValue *eskip.Template
+
+	condition func(*http.Response) bool
 }
 
 // NewTag creates a filter specification for the tracingTag filter.
@@ -27,12 +39,34 @@ func NewTagFromResponse() filters.Spec {
 	return &tagSpec{typ: filters.TracingTagFromResponseName}
 }
 
+func NewTagFromResponseIfStatus() filters.Spec {
+	return &tagSpec{typ: filters.TracingTagFromResponseIfStatusName}
+}
+
 func (s *tagSpec) Name() string {
 	return s.typ
 }
 
 func (s *tagSpec) CreateFilter(args []interface{}) (filters.Filter, error) {
-	if len(args) != 2 {
+	var typ tagFilterType
+
+	switch s.typ {
+	case filters.TracingTagName:
+		if len(args) != 2 {
+			return nil, filters.ErrInvalidFilterParameters
+		}
+		typ = tagRequest
+	case filters.TracingTagFromResponseName:
+		if len(args) != 2 {
+			return nil, filters.ErrInvalidFilterParameters
+		}
+		typ = tagResponse
+	case filters.TracingTagFromResponseIfStatusName:
+		if len(args) != 4 {
+			return nil, filters.ErrInvalidFilterParameters
+		}
+		typ = tagResponseCondition
+	default:
 		return nil, filters.ErrInvalidFilterParameters
 	}
 
@@ -46,23 +80,49 @@ func (s *tagSpec) CreateFilter(args []interface{}) (filters.Filter, error) {
 		return nil, filters.ErrInvalidFilterParameters
 	}
 
-	return &tagFilter{
-		tagFromResponse: s.typ == filters.TracingTagFromResponseName,
-
+	f := &tagFilter{
+		typ:      typ,
 		tagName:  tagName,
 		tagValue: eskip.NewTemplate(tagValue),
-	}, nil
+	}
+
+	if len(args) == 4 {
+		minValue, ok := args[2].(float64)
+		if !ok {
+			return nil, filters.ErrInvalidFilterParameters
+		}
+		maxValue, ok := args[3].(float64)
+		if !ok {
+			return nil, filters.ErrInvalidFilterParameters
+		}
+		minVal := int(minValue)
+		maxVal := int(maxValue)
+		if minVal < 0 || maxVal > 599 || minVal > maxVal {
+			return nil, filters.ErrInvalidFilterParameters
+		}
+
+		f.condition = func(rsp *http.Response) bool {
+			return minVal <= rsp.StatusCode && rsp.StatusCode <= maxVal
+		}
+	}
+
+	return f, nil
 }
 
 func (f *tagFilter) Request(ctx filters.FilterContext) {
-	if !f.tagFromResponse {
+	if f.typ == tagRequest {
 		f.setTag(ctx)
 	}
 }
 
 func (f *tagFilter) Response(ctx filters.FilterContext) {
-	if f.tagFromResponse {
+	switch f.typ {
+	case tagResponse:
 		f.setTag(ctx)
+	case tagResponseCondition:
+		if f.condition(ctx.Response()) {
+			f.setTag(ctx)
+		}
 	}
 }