feat(#3097): use TranslationFailureCollector in Parser (#3111)

It adds TranslationFailureCollector to the Parser. Build method is modified so that translation failures are returned from it. KongClient inspects the failures and in case any occurred, reports TranslationCount metric with SuccessKey=SuccessFalse.

Author: czeslavo

internal/dataplane/kong_client.go

@@ -297,7 +297,11 @@ func (c *KongClient) Update(ctx context.Context) error {
 
 	// initialize a parser
 	c.logger.Debug("parsing kubernetes objects into data-plane configuration")
-	p := parser.NewParser(c.logger, storer)
+
+	p, err := parser.NewParser(c.logger, storer)
+	if err != nil {
+		return fmt.Errorf("failed to create parser: %w", err)
+	}
 	formatVersion := "1.1"
 	if c.AreKubernetesObjectReportsEnabled() {
 		p.EnableKubernetesObjectReports()
@@ -311,13 +315,18 @@ func (c *KongClient) Update(ctx context.Context) error {
 	}
 
 	// parse the Kubernetes objects from the storer into Kong configuration
-	kongstate := p.Build()
-	// todo: does it still make sense to report TranslationCount when Build no longer returns an error?
-	// https://github.com/Kong/kubernetes-ingress-controller/issues/1892
-	c.prometheusMetrics.TranslationCount.With(prometheus.Labels{
-		metrics.SuccessKey: metrics.SuccessTrue,
-	}).Inc()
-	c.logger.Debug("successfully built data-plane configuration")
+	kongstate, translationFailures := p.Build()
+	if failuresCount := len(translationFailures); failuresCount > 0 {
+		c.prometheusMetrics.TranslationCount.With(prometheus.Labels{
+			metrics.SuccessKey: metrics.SuccessFalse,
+		}).Inc()
+		c.logger.Debugf("%d translation failures have occurred when building data-plane configuration", failuresCount)
+	} else {
+		c.prometheusMetrics.TranslationCount.With(prometheus.Labels{
+			metrics.SuccessKey: metrics.SuccessTrue,
+		}).Inc()
+		c.logger.Debug("successfully built data-plane configuration")
+	}
 
 	// generate the deck configuration to be applied to the admin API
 	c.logger.Debug("converting configuration to deck config")

internal/dataplane/parser/parser.go

@@ -51,27 +51,35 @@ type Parser struct {
 	featureEnabledCombinedServiceRoutes             bool
 
 	flagEnabledRegexPathPrefix bool
+	failuresCollector          *TranslationFailuresCollector
 }
 
 // NewParser produces a new Parser object provided a logging mechanism
 // and a Kubernetes object store.
 func NewParser(
 	logger logrus.FieldLogger,
 	storer store.Storer,
-) *Parser {
-	return &Parser{
-		logger: logger,
-		storer: storer,
+) (*Parser, error) {
+	failuresCollector, err := NewTranslationFailuresCollector(logger)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create translation errors collector: %w", err)
 	}
+
+	return &Parser{
+		logger:            logger,
+		storer:            storer,
+		failuresCollector: failuresCollector,
+	}, nil
 }
 
 // -----------------------------------------------------------------------------
 // Parser - Public Methods
 // -----------------------------------------------------------------------------
 
 // Build creates a Kong configuration from Ingress and Custom resources
-// defined in Kubernetes.
-func (p *Parser) Build() *kongstate.KongState {
+// defined in Kubernetes. It returns a slice of TranslationFailures which should
+// be used to provide users with feedback on Kubernetes objects validity.
+func (p *Parser) Build() (*kongstate.KongState, []TranslationFailure) {
 	// parse and merge all rules together from all Kubernetes API sources
 	ingressRules := mergeIngressRules(
 		p.ingressRulesFromIngressV1beta1(),
@@ -120,7 +128,7 @@ func (p *Parser) Build() *kongstate.KongState {
 	// populate CA certificates in Kong
 	result.CACertificates = getCACerts(p.logger, p.storer, result.Plugins)
 
-	return &result
+	return &result, p.popTranslationFailures()
 }
 
 // -----------------------------------------------------------------------------
@@ -174,6 +182,10 @@ func (p *Parser) EnableRegexPathPrefix() {
 	p.flagEnabledRegexPathPrefix = true
 }
 
+func (p *Parser) popTranslationFailures() []TranslationFailure {
+	return p.failuresCollector.PopTranslationFailures()
+}
+
 // -----------------------------------------------------------------------------
 // Parser - Private Methods
 // -----------------------------------------------------------------------------