routesrv: log etag on routes update (#2608)

Signed-off-by: Alexander Yastrebov <[email protected]>

routesrv/eskipbytes.go

@@ -33,7 +33,7 @@ type eskipBytes struct {
 // formatAndSet takes a slice of routes and stores them eskip-formatted
 // in a synchronized way. It returns the length of the stored data, and
 // flags signaling whether the data was initialized and updated.
-func (e *eskipBytes) formatAndSet(routes []*eskip.Route) (_ int, initialized bool, updated bool) {
+func (e *eskipBytes) formatAndSet(routes []*eskip.Route) (_ int, _ string, initialized bool, updated bool) {
 	buf := &bytes.Buffer{}
 	eskip.Fprint(buf, eskip.PrettyPrintInfo{Pretty: false, IndentStr: ""}, routes...)
 	data := buf.Bytes()
@@ -51,7 +51,7 @@ func (e *eskipBytes) formatAndSet(routes []*eskip.Route) (_ int, initialized boo
 	initialized = !e.initialized
 	e.initialized = true
 
-	return len(e.data), initialized, updated
+	return len(e.data), e.etag, initialized, updated
 }
 
 func (e *eskipBytes) ServeHTTP(w http.ResponseWriter, r *http.Request) {

routesrv/polling.go

@@ -96,8 +96,8 @@ func (p *poller) poll(wg *sync.WaitGroup) {
 				"message", LogRoutesEmpty,
 			)
 		case routesCount > 0:
-			routesBytes, initialized, updated := p.b.formatAndSet(routes)
-			logger := log.WithFields(log.Fields{"count": routesCount, "bytes": routesBytes})
+			routesBytes, routesEtag, initialized, updated := p.b.formatAndSet(routes)
+			logger := log.WithFields(log.Fields{"count": routesCount, "bytes": routesBytes, "etag": routesEtag})
 			if initialized {
 				logger.Info(LogRoutesInitialized)
 				span.SetTag("routes.initialized", true)
@@ -110,6 +110,7 @@ func (p *poller) poll(wg *sync.WaitGroup) {
 			}
 			span.SetTag("routes.count", routesCount)
 			span.SetTag("routes.bytes", routesBytes)
+			span.SetTag("routes.etag", routesEtag)
 
 			if updated && log.IsLevelEnabled(log.DebugLevel) {
 				routesById := mapRoutes(routes)