Collect from newly discovered/launched pods

plugins/inputs/prometheus/kubernetes.go

@@ -45,6 +45,7 @@ func (p *Prometheus) start(ctx context.Context) error {
 		if err != nil {
 			return fmt.Errorf("Failed to get current user - %v", err)
 		}
+
 		configLocation := filepath.Join(u.HomeDir, ".kube/config")
 		if p.KubeConfig != "" {
 			configLocation = p.KubeConfig
@@ -76,6 +77,10 @@ func (p *Prometheus) start(ctx context.Context) error {
 	return nil
 }
 
+// An edge case exists if a pod goes offline at the same time a new pod is created
+// (without the scrape annotations). K8s may re-assign the old pod ip to the non-scrape
+// pod, causing errors in the logs. This is only true if the pod going offline is not
+// directed to do so by K8s.
 func (p *Prometheus) watch(ctx context.Context, client *k8s.Client) error {
 	pod := &corev1.Pod{}
 	watcher, err := client.Watch(ctx, "", &corev1.Pod{})
@@ -96,18 +101,44 @@ func (p *Prometheus) watch(ctx context.Context, client *k8s.Client) error {
 				return err
 			}
 
+			// If the pod is not "ready", there will be no ip associated with it.
+			if pod.GetMetadata().GetAnnotations()["prometheus.io/scrape"] != "true" ||
+				!podReady(pod.Status.GetContainerStatuses()) {
+				continue
+			}
+
 			switch eventType {
 			case k8s.EventAdded:
 				registerPod(pod, p)
-			case k8s.EventDeleted:
-				unregisterPod(pod, p)
 			case k8s.EventModified:
+				// To avoid multiple actions for each event, unregister on the first event
+				// in the delete sequence, when the containers are still "ready".
+				if pod.Metadata.GetDeletionTimestamp() != nil {
+					unregisterPod(pod, p)
+				} else {
+					registerPod(pod, p)
+				}
 			}
 		}
 	}
 }
 
+func podReady(statuss []*corev1.ContainerStatus) bool {
+	if len(statuss) == 0 {
+		return false
+	}
+	for _, cs := range statuss {
+		if !cs.GetReady() {
+			return false
+		}
+	}
+	return true
+}
+
 func registerPod(pod *corev1.Pod, p *Prometheus) {
+	if p.kubernetesPods == nil {
+		p.kubernetesPods = map[string]URLAndAddress{}
+	}
 	targetURL := getScrapeURL(pod)
 	if targetURL == nil {
 		return
@@ -116,6 +147,9 @@ func registerPod(pod *corev1.Pod, p *Prometheus) {
 	log.Printf("D! [inputs.prometheus] will scrape metrics from %s", *targetURL)
 	// add annotation as metrics tags
 	tags := pod.GetMetadata().GetAnnotations()
+	if tags == nil {
+		tags = map[string]string{}
+	}
 	tags["pod_name"] = pod.GetMetadata().GetName()
 	tags["namespace"] = pod.GetMetadata().GetNamespace()
 	// add labels as metrics tags
@@ -129,20 +163,16 @@ func registerPod(pod *corev1.Pod, p *Prometheus) {
 	}
 	podURL := p.AddressToURL(URL, URL.Hostname())
 	p.lock.Lock()
-	p.kubernetesPods = append(p.kubernetesPods,
-		URLAndAddress{
-			URL:         podURL,
-			Address:     URL.Hostname(),
-			OriginalURL: URL,
-			Tags:        tags})
+	p.kubernetesPods[podURL.String()] = URLAndAddress{
+		URL:         podURL,
+		Address:     URL.Hostname(),
+		OriginalURL: URL,
+		Tags:        tags,
+	}
 	p.lock.Unlock()
 }
 
 func getScrapeURL(pod *corev1.Pod) *string {
-	scrape := pod.GetMetadata().GetAnnotations()["prometheus.io/scrape"]
-	if scrape != "true" {
-		return nil
-	}
 	ip := pod.Status.GetPodIP()
 	if ip == "" {
 		// return as if scrape was disabled, we will be notified again once the pod
@@ -181,18 +211,13 @@ func unregisterPod(pod *corev1.Pod, p *Prometheus) {
 		return
 	}
 
-	p.lock.Lock()
-	defer p.lock.Unlock()
 	log.Printf("D! [inputs.prometheus] registered a delete request for %s in namespace %s",
 		pod.GetMetadata().GetName(), pod.GetMetadata().GetNamespace())
-	var result []URLAndAddress
-	for _, v := range p.kubernetesPods {
-		if v.URL.String() != *url {
-			result = append(result, v)
-		} else {
-			log.Printf("D! [inputs.prometheus] will stop scraping for %s", *url)
-		}
 
+	p.lock.Lock()
+	defer p.lock.Unlock()
+	if _, ok := p.kubernetesPods[*url]; ok {
+		delete(p.kubernetesPods, *url)
+		log.Printf("D! [inputs.prometheus] will stop scraping for %s", *url)
 	}
-	p.kubernetesPods = result
 }

plugins/inputs/prometheus/kubernetes_test.go

@@ -15,25 +15,29 @@ func TestScrapeURLNoAnnotations(t *testing.T) {
 	url := getScrapeURL(p)
 	assert.Nil(t, url)
 }
+
 func TestScrapeURLAnnotationsNoScrape(t *testing.T) {
 	p := &v1.Pod{Metadata: &metav1.ObjectMeta{}}
 	p.Metadata.Name = str("myPod")
 	p.Metadata.Annotations = map[string]string{"prometheus.io/scrape": "false"}
 	url := getScrapeURL(p)
 	assert.Nil(t, url)
 }
+
 func TestScrapeURLAnnotations(t *testing.T) {
 	p := pod()
 	p.Metadata.Annotations = map[string]string{"prometheus.io/scrape": "true"}
 	url := getScrapeURL(p)
 	assert.Equal(t, "http://127.0.0.1:9102/metrics", *url)
 }
+
 func TestScrapeURLAnnotationsCustomPort(t *testing.T) {
 	p := pod()
 	p.Metadata.Annotations = map[string]string{"prometheus.io/scrape": "true", "prometheus.io/port": "9000"}
 	url := getScrapeURL(p)
 	assert.Equal(t, "http://127.0.0.1:9000/metrics", *url)
 }
+
 func TestScrapeURLAnnotationsCustomPath(t *testing.T) {
 	p := pod()
 	p.Metadata.Annotations = map[string]string{"prometheus.io/scrape": "true", "prometheus.io/path": "mymetrics"}
@@ -50,21 +54,36 @@ func TestScrapeURLAnnotationsCustomPathWithSep(t *testing.T) {
 
 func TestAddPod(t *testing.T) {
 	prom := &Prometheus{}
+
 	p := pod()
 	p.Metadata.Annotations = map[string]string{"prometheus.io/scrape": "true"}
 	registerPod(p, prom)
 	assert.Equal(t, 1, len(prom.kubernetesPods))
 }
+
+func TestAddMultipleDuplicatePods(t *testing.T) {
+	prom := &Prometheus{}
+
+	p := pod()
+	p.Metadata.Annotations = map[string]string{"prometheus.io/scrape": "true"}
+	registerPod(p, prom)
+	p.Metadata.Name = str("Pod2")
+	registerPod(p, prom)
+	assert.Equal(t, 1, len(prom.kubernetesPods))
+}
+
 func TestAddMultiplePods(t *testing.T) {
 	prom := &Prometheus{}
 
 	p := pod()
 	p.Metadata.Annotations = map[string]string{"prometheus.io/scrape": "true"}
 	registerPod(p, prom)
 	p.Metadata.Name = str("Pod2")
+	p.Status.PodIP = str("127.0.0.2")
 	registerPod(p, prom)
 	assert.Equal(t, 2, len(prom.kubernetesPods))
 }
+
 func TestDeletePods(t *testing.T) {
 	prom := &Prometheus{}
 

plugins/inputs/prometheus/prometheus.go

@@ -42,7 +42,7 @@ type Prometheus struct {
 	// Should we scrape Kubernetes services for prometheus annotations
 	MonitorPods    bool `toml:"monitor_kubernetes_pods"`
 	lock           sync.Mutex
-	kubernetesPods []URLAndAddress
+	kubernetesPods map[string]URLAndAddress
 	cancel         context.CancelFunc
 	wg             sync.WaitGroup
 }
@@ -115,21 +115,23 @@ type URLAndAddress struct {
 	Tags        map[string]string
 }
 
-func (p *Prometheus) GetAllURLs() ([]URLAndAddress, error) {
-	allURLs := make([]URLAndAddress, 0)
+func (p *Prometheus) GetAllURLs() (map[string]URLAndAddress, error) {
+	allURLs := make(map[string]URLAndAddress, 0)
 	for _, u := range p.URLs {
 		URL, err := url.Parse(u)
 		if err != nil {
 			log.Printf("prometheus: Could not parse %s, skipping it. Error: %s", u, err.Error())
 			continue
 		}
-
-		allURLs = append(allURLs, URLAndAddress{URL: URL, OriginalURL: URL})
+		allURLs[URL.String()] = URLAndAddress{URL: URL, OriginalURL: URL}
 	}
+
 	p.lock.Lock()
 	defer p.lock.Unlock()
 	// loop through all pods scraped via the prometheus annotation on the pods
-	allURLs = append(allURLs, p.kubernetesPods...)
+	for k, v := range p.kubernetesPods {
+		allURLs[k] = v
+	}
 
 	for _, service := range p.KubernetesServices {
 		URL, err := url.Parse(service)
@@ -144,7 +146,11 @@ func (p *Prometheus) GetAllURLs() ([]URLAndAddress, error) {
 		}
 		for _, resolved := range resolvedAddresses {
 			serviceURL := p.AddressToURL(URL, resolved)
-			allURLs = append(allURLs, URLAndAddress{URL: serviceURL, Address: resolved, OriginalURL: URL})
+			allURLs[serviceURL.String()] = URLAndAddress{
+				URL:         serviceURL,
+				Address:     resolved,
+				OriginalURL: URL,
+			}
 		}
 	}
 	return allURLs, nil
@@ -313,6 +319,9 @@ func (p *Prometheus) Stop() {
 
 func init() {
 	inputs.Add("prometheus", func() telegraf.Input {
-		return &Prometheus{ResponseTimeout: internal.Duration{Duration: time.Second * 3}}
+		return &Prometheus{
+			ResponseTimeout: internal.Duration{Duration: time.Second * 3},
+			kubernetesPods:  map[string]URLAndAddress{},
+		}
 	})
 }