Implement /templates HTTP endpoint

cmd/goflow2/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"flag"
 	"fmt"
@@ -307,6 +308,26 @@ func main() {
 			os.Exit(1)
 		}
 
+		// Add optional HTTP handler for templates
+		if nfP, ok := p.(*utils.NetFlowPipe); ok && *TemplatePath != "" {
+			http.HandleFunc(*TemplatePath, func(wr http.ResponseWriter, r *http.Request) {
+				templates := nfP.GetTemplatesForAllSources()
+				if body, err := json.MarshalIndent(templates, "", "  "); err != nil {
+					slog.Error("error writing JSON body for /templates", slog.String("error", err.Error()))
+					wr.WriteHeader(http.StatusInternalServerError)
+					if _, err := wr.Write([]byte("Internal Server Error\n")); err != nil {
+						slog.Error("error writing HTTP", slog.String("error", err.Error()))
+					}
+				} else {
+					wr.Header().Add("Content-Type", "application/json")
+					wr.WriteHeader(http.StatusOK)
+					if _, err := wr.Write(body); err != nil {
+						slog.Error("error writing HTTP", slog.String("error", err.Error()))
+					}
+				}
+			})
+		}
+
 		decodeFunc = p.DecodeFlow
 		// intercept panic and generate error
 		decodeFunc = debug.PanicDecoderWrapper(decodeFunc)

decoders/netflow/templates.go

@@ -20,6 +20,7 @@ type NetFlowTemplateSystem interface {
 	RemoveTemplate(version uint16, obsDomainId uint32, templateId uint16) (interface{}, error)
 	GetTemplate(version uint16, obsDomainId uint32, templateId uint16) (interface{}, error)
 	AddTemplate(version uint16, obsDomainId uint32, templateId uint16, template interface{}) error
+	GetTemplates() FlowBaseTemplateSet
 }
 
 func (ts *BasicTemplateSystem) GetTemplates() FlowBaseTemplateSet {

metrics/templates.go

@@ -70,3 +70,7 @@ func (s *PromTemplateSystem) RemoveTemplate(version uint16, obsDomainId uint32,
 
 	return template, err
 }
+
+func (s *PromTemplateSystem) GetTemplates() netflow.FlowBaseTemplateSet {
+	return s.wrapped.GetTemplates()
+}

utils/pipe.go

@@ -3,6 +3,7 @@ package utils
 import (
 	"bytes"
 	"fmt"
+	"maps"
 	"sync"
 
 	"github.com/netsampler/goflow2/v2/decoders/netflow"
@@ -223,6 +224,23 @@ func (p *NetFlowPipe) DecodeFlow(msg interface{}) error {
 func (p *NetFlowPipe) Close() {
 }
 
+// Return a copy of the template set for all known netflow sources. Useful for exporting the
+// templates via an HTTP endpoint
+func (p *NetFlowPipe) GetTemplatesForAllSources() map[string]map[uint64]interface{} {
+	p.templateslock.RLock()
+	defer p.templateslock.RUnlock()
+
+	ret := make(map[string]map[uint64]interface{})
+	for k, v := range p.templates {
+		templateRef := v.GetTemplates()
+		var templateCopy = make(netflow.FlowBaseTemplateSet)
+		maps.Copy(templateCopy, templateRef)
+		ret[k] = templateCopy
+	}
+
+	return ret
+}
+
 type AutoFlowPipe struct {
 	*SFlowPipe
 	*NetFlowPipe